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Horticulture Newsletter 2015, No. 13

3/30/2015

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Video of the Week:
Self-Watering Planter Saves Time

Vegetables
Starting Tomatoes Early

soil temperature probe
If you would like to have your tomato plants produce earlier in the year, there are certain things to keep in mind. Most people who try to get a jump on the season set their tomatoes out early and hope they do well. However, that is often not a good plan, as tomatoes have to have certain requirements before they will grow well. Those requirements are an acceptable soil temperature for root growth and an acceptable air temperature for both plant growth and fruit set.

Root Growth: Tomatoes need a soil temperature of at least 55 degrees to do well. Plastic mulch is most commonly used to warm the soil. Several days may be needed to raise the soil temperature. Check the soil temperature 2.5 inches deep in the soil at about 11:00 a.m. If that is not possible, check the temperature before leaving for work and again when your return and use the average of the two.  You may wish to lay a drip irrigation line before installing the plastic to make watering more convenient.  See accompanying article on laying plastic mulch.

Air Temperature: Plants must be protected from frost. Hot caps or water teepees are placed over the young plants to provide protection as well as a higher average temperature to encourage growth. Eventually the plants will outgrow the cover and start to develop flowers. But if the temperature goes below 55 degrees at night, tomato flowers may not set. The plant is not hurt, but the blossom will not set fruit or, if it does set fruit, the fruit is often misshapen.

How early can you transplant? Start with a date about 2 weeks earlier than normal. (Ward Upham)

Herbicides for Home Vegetable Gardens

vegetable garden
Though mulches and hoeing are usually all that is needed for small vegetable gardens, homeowners with large areas may need the help of herbicides to keep ahead of the weeds. One preemergence and one postemergence herbicide can be used on home vegetable gardens.

The preemergence herbicide is trifluralin. Preemergence herbicides kill weed seeds as they germinate. They usually have no effect on weeds that have emerged. Therefore, they must be put on either before weeds come up in the spring or after weeds have been physically removed. The preemergence herbicide trifluralin is sold under the trade names of Treflan, Preen, Miracle-Gro Garden Weed Preventer, Gordon's Garden Weed Preventer Granules and Monterey Vegetable and Ornamental Weeder.

The postemergence herbicide is sethoxydim. This product only kills grasses; broadleaves are not affected. It can be sprayed directly over the top of many vegetables. Sethoxydim is sold as Poast, Monterey Grass Getter, and Hi-Yield Grass Killer. A second postemergence herbicide called fluazifop-p-butyl is labeled for commercial growers as Fusilade, but I haven't found vegetables listed on the homeowner labels, “Over the Top Grass Killer” and “Grass-No-More.” Also, the other homeowner products mentioned above often do not have as many vegetables on the label as the commercial products. Even among the homeowner products with the same active ingredient, there may be slight differences among labels. Check product labels to be sure the crop is listed. Here is a list of herbicides and the crops for which they are labeled. Many of these crops have application restrictions. For example, trifluralin can be used on asparagus, but must be applied before spears emerge. (Ward Upham)

Vegetable      Treflan    Poast
Asparagus       X               X
Beans               X               X
Broccoli           X               X
Cabbage          X               X
Carrot              X               --
Cauliflower     X               X  
Corn, Sweet    --               --
Cucumber       X               X
Eggplant         --               X
Lettuce            --               X
Greens             X               --
Muskmelon   X              X
Okra                 X               --
Onion              --               X
Peas                 X                X
Pepper             X               X
Potato              X               X
Pumpkin         --               X
Spinach           --               X
Squash            --               X
Sweetpotato    --              --
Tomato            X               X
Turnip              X               --
Watermelon   X               X

Turfgrass
Proper Timing for Crabgrass Preventers

Picture
Crabgrass preventers are another name for preemergence herbicides that prevent crabgrass seeds from developing into mature plants. Many people have a somewhat foggy idea of how they work. They do not keep the seed from germinating but kill the young germinating plant.  Crabgrass preventers are just that – preventers. With few exceptions they have no effect on existing crabgrass plants, so they must be applied before germination. Additionally, preventers do not last forever once applied to the soil. Microorganisms and natural processes begin to gradually break them down soon after they are applied. If some products are applied too early, they may have lost much of their strength by the time they are needed. Most crabgrass preventers are fairly ineffective after about 60 days, but there is considerable variation among products. (Dimension and Barricade last longer. See below.)

For most of Kansas, crabgrass typically begins to germinate around May 1 or a little later. April 15 is a good target date for applying preventer because it gives active ingredients time to evenly disperse in the soil before crabgrass germination starts. The April 15 target works well for most of the state, but for southeast Kansas April 1 is more appropriate, and for northwest Kansas May 1 is best. Additionally, weather varies from one spring to the next, and with it the timing of crabgrass germination. It is often better to base timing on the bloom of ornamental plants. The Eastern Redbud tree is a good choice for this purpose. When the trees in your area approach full bloom, apply crabgrass preventer. A follow-up application will be needed about 8 weeks later unless you are using Dimension or Barricade. Products that do require a follow-up application include pendimethalin (Scotts Halts) and Team (Hi-Yield Crabgrass Control). Dimension and Barricade are the only two products that give season-long control of crabgrass from a single application. In fact, they can be applied much earlier than April 15 and still have sufficient residual strength to last the season. Barricade can even be applied in the fall for crabgrass control the next season.

Dimension can be applied as early as March 1. Because of the added flexibility in timing, these products are favorites of lawn care companies who have many customers to service in the spring. Though Dimension cannot be applied as early as Barricade, it is the herbicide of choice if it must be applied later than recommended. It is the exception to the rule that preemergence herbicides do not kill existing weeds. Dimension can kill crabgrass as long as it is young (two- to three-leaf stage). Dimension is also the best choice if treating a lawn that was planted late last fall.  Normally a preemergence herbicide is not recommended unless the lawn has been mowed two to four times. But Dimension is kind to young tall fescue, perennial ryegrass, and Kentucky bluegrass seedlings and some formulations can be applied as early as two weeks after the first sign of germination. However, read the label of the specific product you wish to use to insure that this use is allowed.  Lawns established in the fall can be safely treated with Dimension the following spring even if they have not been mowed. Note that products containing Dimension and Barricade may use the common name rather than the trade name. The common chemical name for Dimension is dithiopyr and for Barricade is prodiamine. Remember, when using any pesticide, read the label and follow instructions carefully.

We recommend crabgrass preventers be applied before fertilizer so that the grass isn’t Encouraged to put on too much growth too early. However, it may be difficult to find products that contain preemergents without fertilizer. Those that don’t contain fertilizer are listed below. I didn’t find any products containing Barricade that did not also have a fertilizer. If anyone knows of other products that should be listed, let us know and we will publish them in a later newsletter.

Pendimethalin
      - Scotts Halts
Team (Benefin + Trifluralin)
      - Hi-Yield Crabgrass Control
Dimension
      - Hi-Yield Turf & Ornamental Weed and Grass Stopper
      - Bonide Crabgrass & Weed Preventer
      - Green Light Crabgrass Preventer
 (Ward Upham)

How Low Should You Go?

Push mower
We often are asked whether it is good to mow lower in the spring. The answer is yes and no. It doesn’t hurt to mow lower than normal the first mowing or two. As a matter of fact, it can actually speed green-up by removing old, dead grass and allowing the soil to warm up faster. But the mowing height should be raised to normal after the first or second cutting to discourage crabgrass.

Crabgrass seed must have light to germinate, and a high mowing height will shade the soil. Also, root depth and mowing height are related on upright growing grasses such as tall fescue and Kentucky bluegrass — the higher the height of cut, the deeper the root system. A deeper root system means a more drought-resistant turf.

So, how low should you go on the first cutting? On tall fescue and Kentucky bluegrass, you can mow as low as 1 to 1½ inches. Be careful you don't go so low that you scalp the turf. Normal mowing height for Kentucky bluegrass is 2 to 3 inches and for tall fescue is 3 to 3½ inches. (Ward Upham)

Ornamentals:
Brown Coloration on Junipers

junipers cones
Certain eastern redcedar and various other junipers are showing a brownish cast when viewed from a distance. This may be the male cones. Male cones are on the tips of the foliage and look somewhat like a cross between a miniature hand grenade and a pinecone. Shaking the branches on dry days often releases a cloud of pollen. Most junipers are dioecious, meaning they have both male and female plants. About half the junipers (the males) have this coloration. Female cones are much less obvious. If you are concerned about the brown color, check plants to ensure male cones are the cause. If they are, this is normal and will fade with time.  (Ward Upham)

Miscellaneous:
Laying Plastic Mulch

Plastic mulch
Plastic mulch is sometimes used to start vegetables such as tomatoes and melons earlier than normal. Commercial growers use a machine to lay the mulch, but home gardeners must do this by hand. Following are some tips on how this is done.

1. Fertilize according to soil test. You won't be able to add fertilizer after the plastic is down.

2. Work the soil so that the bed can be easily shaped.

3. Use a garden hoe to form a trench along all edges of the plastic. The soil should be pulled to the outside of the bed. The trench should be formed six inches in from the edge of the plastic and extend along both sides and both ends. The trench should be deep and wide enough to bury six inches of plastic.

4. Lay trickle irrigation tube down the center of the bed. This isn't absolutely necessary but it makes it much easier to water. Overhead watering will hit the plastic and roll off.

5. Lay the plastic down and cover the edges with soil. You may need to slit the edge of the plastic where the trickle irrigation tube enters the end of the bed.

6. Plant when the soil temperature reaches the correct temperature for the crop (55 degrees for tomatoes and 60 degrees for melons) at a 2.5-inch depth. Check the temperature at about 11:00 a.m. to get a good average temperature. Check for several days in a row to ensure the temperature is stable. (Ward Upham)


Organic Sources of Nitrogen Fertilizer

fertilizer
Most of the soil tests we receive for vegetable gardens are high in phosphorus and potassium, leaving nitrogen as the nutrient needed most.  However, many of our organic fertilizers contain similar amounts of all three nutrients. So, what can we use that provides more nitrogen than phosphorus and potassium? Following is a short list of such fertilizers.



Product                        Analysis           Pounds/100 sq. ft.             Notes 
Blood Meal                   12-0-0                      5 - 10                       Can burn plants if overapplied.

Cottonseed Meal        6-0.4-1.5                     10                          May have pesticide carry over unless labeled as
                                                                                                                pesticide-free.
Soybean Meal               7-2-1                            8

Feed stores will often sell these products. Colorado State University has an excellent publication on organic fertilizers at http://cmg.colostate.edu/gardennotes/234.pdf   (Ward Upham)

Pests
Spring Has Sprung - Eastern Tent Caterpillars

Eastern Tent Caterpillars
The March Equinox officially kicking off the 2015 Spring season for Kansas was at 5:45 PM CDT  Friday, March 20.  Earlier that day, when returning home from work, I checked the Eastern tent caterpillar egg masses that I placed in my flowering crab back in January --- still no hatch.  Saturday morning, March 21, before heading out for the day, I observed newly emerged larvae clustered one of the egg masses.  Coincidence?  Yes, definitely so.  Eastern tent caterpillars don’t always first appear so close to the exact first day of Spring as seen below on the compilation of dates of previous “first appearances.”  Using ETC egg hatch as an indicator, our current Spring is 2 ½ weeks ahead of last year’s.

In years where ETC hatch was on the early side, larvae had to content themselves by nibbling on swollen leaf buds.  (See photo)

This year, budbreak occurred March 12 --- well ahead of egg hatch.  Thus, the “current salad bar” is filled with young tender foliage for larvae to feast upon.


2002      2003    2004    2005      2006      2007      2008        2009        2010      2011      2012      2013     2014
Mar.       Mar.     Mar.     Mar.       Mar.       Mar.       Mar.         Mar.         Mar.       Mar.       Mar.      Mar.     Apr.
20           26           21         29            30           16            28              23             31            23            14           30          7

What does this mean for homeowners with landscape interests?  If they have previously experienced ETC, their biggest objection likely will be the eventual appearance of unsightly web masses (“tents”) which are restricted to branch crotch areas.  Currently, the feeding damage attributable to small hatchling caterpillars (barely 1 mm in length) is virtually undetectable.  In several weeks after larvae have increased in size, their enlarged “tents” will become more readily visible. The most effective removal of tents within arms’ reach can be accomplished by simply “finger-raking.”  Do this during the day when the night-foraging caterpillars are clustered “at home” within their tent. Thus, both the webbing and caterpillars can be disposed of. 

Alternatively, let them be.  While some defoliation caused by larger caterpillars may eventually become apparent, they will complete and cease their yearly feeding  phase in early May.  Soon thereafter, leafless branches will rapidly refoliate, thus restoring a normal appearance. (Bob Bauernfeind)

Contributors: Bob Bauernfeind, Entomologist Ward Upham, Extension Associate

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Horticulture Newsletter 2015, No. 12

3/24/2015

0 Comments

 

Video of the Week:
Caring for Knockout Roses

Flowers:
Care for Spring-Flowering Bulbs

Picture
As spring-flowering bulbs go through the flowering process, keep three care tips in mind:

1. If practical, remove spent flowers with a scissors or a hand pruner. This allows the plant to conserve its energy for bloom the next year rather than using it to produce seed.

2. Allow foliage to die naturally — it is needed to manufacture food that will be stored in the bulb and used for next year’s flowers.

3. Don’t fertilize. The roots of these plants start to shut down after flowering. Fertilizer applied at this time is wasted. Instead, fertilize during the fall at the time bulbs are normally planted and again in the spring when new growth pokes out of the ground. (Ward Upham)

Preventing Weeds in Flower Beds

Picture
Often mulch does a good enough job in perennial flower beds to prevent weeds but sometimes the mulch needs a little help.  In annual beds, judicious hoeing will keep weeds down until the foliage forms a canopy that prevents weed germination. However, a lack of time may have you considering an easier way than hoeing or pulling weeds that come through mulch. Preemergence herbicides can help though you should not expect 100% control.

Preemergence herbicides do not keep the weed seed from germinating but kill the young plant as it starts to grow.  It is necessary to water these products in (1/4 inch of water) so that the young weed root will contact the herbicide. Be aware that most of these products are more effective on grassy weeds such as crabgrass rather than broadleaves such as dandelions or spurge. 

These herbicides often have no effect on existing plants, so they must be applied before the weed seed germinates. Additionally, preventers do not last forever once applied to the soil. Microorganisms and natural processes begin to gradually break them down soon after they are applied.  However, all should last long enough so that you get canopy cover before the herbicide wears off.

Read the label for information on when to apply the product.  Also, be sure the ornamental plants within the bed area are on the label before purchasing the product.  See below for products we can use.

      Dimension (dithopyr)
            - Hi-Yield Turf & Ornamental Weed and Grass Stopper
           - Bonide Crabgrass & Weed Preventer

      Treflan (trifluralin)
          - Hi-Yield Herbicide Granules Weed and Grass Preventer
          - Miracle Gro Garden Weed Preventer
          - Preen Weed Preventer

(Ward Upham)

Vegetables:
Asparagus Time

Picture
Asparagus is one of those vegetables where freshness is incredibly important. If you have never eaten asparagus fresh out of the garden, try it. It may convince you to grow some of your own. For those who have an asparagus patch, the new spears should be appearing soon. The first asparagus that comes through the ground always seems to take a long time to reach harvest size.  That is because asparagus growth is temperature dependent. The higher the day and nighttime temperatures, the faster it grows. Also, the longer the spear, the quicker the growth. As the season progresses and spears get longer, the growth rate increases.

Harvest asparagus by snapping or cutting. Snapping is quick and easy. Simply bend the stalk near the base until it breaks. Snapped ends dry quickly so refrigerate or use soon after harvest. If you cut asparagus, use a sharp knife to detach the spears slightly below ground level. This base is woodier than snapped asparagus, so it doesn't lose water as quickly. Cut off woody ends before cooking. (Ward Upham)

Fruit:
Apple Tree Sprays

Picture
Two common diseases on apple trees are cedar apple rust and apple scab. Though some apple varieties are resistant to these diseases — including Liberty, Jonafree, Redfree, Freedom, Williams Pride and Enterprise — most varieties are susceptible. For a description of disease-resistant varieties, go to http://ohioline.osu.edu/hyg-fact/1000/1401.html 

Fungicide sprays during April and May are critical to preventing disease on susceptible varieties. A fungicide that is available to homeowners and very effective for control of apple scab and cedar apple rust is myclobutanil (Immunox). There are several formulations of Immunox but only one is labeled for fruit. Check the label.

Sprays should be done on a 7- to 10-day schedule to keep the protective chemical cover on the rapidly developing leaves and fruit. An insecticide will need to be added to this mixture after petal drop to prevent damage from codling moths that cause wormy apples. Methoxychlor or malathion can be used as an insecticide. In order to protect bees, DO NOT use any insecticide during bloom.

Although gardeners may continue to use myclobutanil throughout the season, certain other fungicides are more effective on summer diseases such as sooty blotch and fly speck. Consider switching to Captan or to a fruit spray mixture about June 1. A spreader-sticker can be added to the fungicide-insecticide chemical mixture to improve the distribution and retention of the pest control chemicals over the leaves and fruit. A hard, driving rain of about 1 inch or more will likely wash chemicals from the leaves and fruit. In such cases, another application should be made. You can find information on controlling insects and diseases on fruit trees in our publication titled "Fruit Pest Control for Home Gardens" at http://www.ksre.ksu.edu/bookstore/pubs/c592.pdf   Below is the spray schedule I use.  Sprays are applied ever 10 days until 2 weeks before harvest.

      Blossoms reach pink stage, usually the first half of April: Immunox
      Petal Drop: Add malathion to the Immunox and so the mixture is Immunox + malathion
      June 1: Replace Immunox with Captan.  The mixture is now Captan + malathion
      Stop spraying 2 weeks before harvest.  (Ward Upham)

Frost Tolerance of Apricots and Peaches

Picture
Growers of apricots and peaches often wonder at what temperature fruit buds are killed. These two tree fruits bloom very early and are often caught by a late frost. The following will give you some guidelines but remember that the actual damage is going to be influenced by the weather before the temperature drops. An extended warm spell before the cold snap may result in more damage due to a loss in cold hardiness. The stages listed are for the fruit buds.

Apricot

Stage          10% Kill (°F)     90% Kill (°F) 
First white         24                    14
First Bloom       25                    19
Full Bloom         27                    22
In the Shuck      27                   24
Green Fruit        28                   25

Peach

Stage                     10% Kill (°F)       90% Kill (°F) 
Swollen bud                  18                     2
Half-inch green           23                     5
Pink                                 25                     18
Bloom                             27                     24
Petal fall                         28                     25
Fruit set                         28                     25

To check for low temperature injury to fruit buds or blossoms, use a sharp knife and cut them in half longitudinally (from top to bottom). If the tiny seed in the center is white to cream color no damage has been done. But if the seed in several buds or blossoms is dark brown or black, it has been killed.

It is possible to give some protection to blossoms from freezing by covering the tree with a bed spread, blanket or similar fabric. Old-fashioned Christmas lights distributed around the tree will help to give additional protection. The newer, smaller Christmas lights do not give off enough heat and are not recommended. Of course the practicality of this method of protection depends upon the size and number of trees.

Sprinkling the tree with water throughout the freezing period can also protect the blossoms. Sprinklers should be started before the temperature drops to freezing to be sure ice does not block the garden hose or water line. Continue until the temperature warms. With this protection method, there is the potential of creating an ice storm. If temperatures remain below freezing for several hours, ice will accumulate on the branches and limbs. The weight from the ice may cause branches and limbs to break causing severe, and possibly permanent, damage to the tree structure. Also, if water drainage from the soil is slow and the water displaces oxygen from the roots, damage to trees may result.  (Ward Upham)

Turfgrass:
Proper Timing for Crabgrass Preventers

Picture
Crabgrass preventers are another name for preemergence herbicides that prevent crabgrass seeds from developing into mature plants. Many people have a somewhat foggy idea of how they work. They do not keep the seed from germinating but kill the young germinating plant. Crabgrass preventers are just that – preventers. With few exceptions they have no effect on existing crabgrass plants, so they must be applied before germination. Additionally, preventers do not last forever once applied to the soil. Microorganisms and natural processes begin to gradually break them down soon after they are applied. If some products are applied too early, they may have lost much of their strength by the time they are needed. Most crabgrass preventers are fairly ineffective after about 60 days, but there is considerable variation among products. (Dimension and Barricade last longer. See below.)

For most of Kansas, crabgrass typically begins to germinate around May 1 or a little later. April 15 is a good target date for applying preventer because it gives active ingredients time to evenly disperse in the soil before crabgrass germination starts. The April 15 target works well for most of the state, but for southeast Kansas April 1 is more appropriate, and for northwest Kansas, May 1 is best. Additionally, weather varies from one spring to the next, and with it the timing of crabgrass germination. It is often better to base timing on the bloom of ornamental plants. The Eastern Redbud tree is a good choice for this purpose. When the trees in your area approach full bloom, apply crabgrass preventer. A follow-up application will be needed about 8 weeks later unless you are using Dimension or Barricade. Products that do require a follow-up application include pendimethalin (Scotts Halts) and Team (Hi-Yield Crabgrass Control). Dimension and Barricade are the only two products that give season-long control of crabgrass from a single application. In fact, they can be applied much earlier than April 15 and still have sufficient residual strength to last the season. Barricade can even be applied in the fall for crabgrass control the next season.

Dimension can be applied as early as March 1. Because of the added flexibility in timing, these products are favorites of lawn care companies who have many customers to service in the spring.

Though Dimension cannot be applied as early as Barricade, it is the herbicide of choice if it must be applied later than recommended. It is the exception to the rule that preemergence herbicides do not kill existing weeds. Dimension can kill crabgrass as long as it is young (two- to three-leaf stage). Dimension is also the best choice if treating a lawn that was planted late last fall.  Normally a preemergence herbicide is not recommended unless the lawn has been mowed two to four times. But Dimension is kind to young tall fescue, perennial ryegrass, and Kentucky bluegrass seedlings and some formulations can be applied as early as two weeks after the first sign of germination. However, read the label of the specific product you wish to use to insure that this use is allowed.  Lawns established in the fall can be safely treated with Dimension the following spring even if they have not been mowed. Note that products containing Dimension and Barricade may use the common name rather than the trade name. The common chemical name for Dimension is dithiopyr and for Barricade is prodiamine. Remember, when using any pesticide, read the label and follow instructions carefully.

We recommend crabgrass preventers be applied before fertilizer so that the grass isn’t encouraged to put on too much growth too early. However, it may be difficult to find products that contain preemergents without fertilizer. Those that don’t contain fertilizer are listed below.  I didn’t find any products containing Barricade that did not also have a fertilizer. If anyone knows of other products that should be listed, let us know and we will publish them in a later newsletter.

Pendimethalin
        - Scotts Halts

Team (Benefin + Trifluralin)
        - Hi-Yield Crabgrass Control

Dimension
        - Hi-Yield Turf & Ornamental Weed and Grass Stopper
        - Bonide Crabgrass & Weed Preventer
        - Green Light Crabgrass Preventer

 (Ward Upham)

Miscellaneous:
Transplant Solutions and Sidedressing

Picture
Transplant solutions are mild fertilizer solutions that are applied to newly transplanted vegetables and flowers. Transplant solutions are also called starter solutions or root stimulators. Plants not given a transplant solution often develop a purplish tinge to the leaves caused by a phosphorus deficiency. Surprisingly, the soil may have plenty of phosphorus but plants often have difficulty taking up nutrients in cool soils. The starter solution places soluble nutrients near the roots so the plants get off to a good, strong start.

Transplant solutions (root stimulators) are available for sale but it is also possible to make your own transplant solution from a fertilizer that contains more phosphorus than nitrogen or potassium such as a 5-10-5, 10-20-10 or 11-15-11.  Mix 2 to 3 tablespoons of one of the above fertilizers in a gallon of water several hours before use. The fertilizer won't completely dissolve but enough will go into solution to get plants off to a good start. Use about 1 cup of transplant solution for each transplant.

Sidedressing is a fertilization done after the plants are established. A fertilizer containing primarily nitrogen is used to keep plants growing and productive. Nitrate of soda (16-0-0) is often used at the rate of 2 pounds fertilizer per 100 feet of row. More commonly available lawn fertilizers such as a 30-3-3, 29-5-4 or something similar can also be used but cut the rate in half.

Be sure any lawn fertilizer used does not contain weed preventers or weed killers. Note that most fertilizers weigh about 1 pound per pint of product.

We have a sidedressing sheet available that lists crops, rate of fertilizer application and timing of application(s) for many common vegetables as well as annual flowers. The sheet can be viewed at http://www.hfrr.ksu.edu/doc1991.ashx   (Ward Upham)

Contributors: Ward Upham, Extension Associate

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Horticulture Newsletter 2015, No. 11

3/17/2015

0 Comments

 

Video of the Week:
Pruning Fruit Trees

Turfgrass:
Core Aeration of Cool-Season Lawns

core aerator
If you are planning to core-aerate your tall fescue or Kentucky bluegrass lawn this spring, reserve a machine now so you can get the job done in March or early-April. Coring early in the spring gives cool-season lawns a chance to recover before crabgrass and other warm-season annual weeds start to germinate.

Core-aerating is one of the best things you can do for your lawn. It relieves compaction, hastens thatch decomposition, increases water infiltration and helps promote better root growth. Pay attention to the soil moisture level when coring. The soil should easily crumble when worked between the fingers. If it is too wet, the machine's tines will plug and it will merely punch holes in the wet soil, which increases compaction. If it is too dry, the tines will not be able to penetrate deeply enough to be of benefit. (Ward Upham)

Vegetables:
Frost Proof Vegetable Plants

frost on vegetable seedling
Certain vegetables can withstand cold spring temperatures as long as they have been toughened up by gradually exposing them to sunlight and outdoor temperatures. This “hardening off” process usually takes about a week. Reducing watering and temperature is the key to toughening up transplants. If possible, move transplants outside for a portion of each day. Start by placing them in a shady, protected location and gradually move them into a more exposed, sunny location as the week progresses. Hardened off cabbage, broccoli, cauliflower and onions can withstand temperatures near 20 F without being killed. Lettuce plants are not quite as tough but will be okay if exposed to temperatures in the mid 20s. Don’t hesitate to put these plants out now if extreme cold is not forecast. (Ward Upham)

Controlling Weeds in Home Garden Asparagus Beds

asparagus
The best time to control weeds in asparagus is early spring before the asparagus emerges. A light tilling (or hoeing) that is shallow enough to avoid the crowns will eliminate existing weeds. Many gardeners like to mix in organic matter during the same operation.

Herbicides can be used before asparagus emerges. Glyphosate (Roundup, Killzall) will kill weeds that are actively growing, and the preemergence herbicide trifluralin can be used to kill weed seeds as they germinate. Trifluralin is found in several products, but not all of them list asparagus on the label. Those that do have asparagus on the label include Miracle-Gro Weed Preventer Granules and Monterey Vegetable and Ornamental Weeder. Mulch can also be used to keep weeds from invading.

No herbicides can be used during harvest. The end of harvest presents another opportunity. Remove all fern and spears and apply Roundup to control virtually all of the weeds present. Past the harvest season and after regrowth of the asparagus, options are limited. Products that contain sethoxydim can be applied to asparagus to kill grassy weeds. Sethoxydim has no effect on broadleaves including asparagus. Two sethoxydim products available to homeowners and labeled for asparagus are Monterey Grass Getter and Hi-Yield Grass Killer. With broadleaves, the only option is to pull them and look forward to next year. (Ward Upham)

Remove Fern and Fertilize Asparagus

asparagus bed in winter
If you haven’t removed last year’s growth from asparagus plants, now is the time. Asparagus comes up around the first of April in Manhattan but will be earlier in southern Kansas and a bit later further north.

Also, asparagus benefits from a fertilizer application early spring. Fertilize according to a soil test or add 1 to 2 pounds of a 10-20-10 fertilizer per 20 feet of row before growth starts. If a soil test shows that only nitrogen is needed, apply 1 pound of a 16-0-0 product or ½ pound of a 30-4-5, 27-3-3 or similar fertilizer per 20 feet of row. Incorporate lightly with a tiller or rake in fertilizer before spears emerge. Fertilize again at the same rate after the last harvest. (Ward Upham)

Flowers:
Pruning Hybrid-Tea Roses

rose after pruning
The best time to prune roses is in the spring before new growth appears and after danger of killing frost. Be sure to remove dead stubs. Otherwise, canker fungi may invade stubs and progress into healthy tissue during the summer. Use sharp shears and make cuts at a 45-degree angle about a quarter-inch above healthy buds. How much to prune after dead wood removal depends on the type of rose.

For shrub roses, pruning usually consists of removing dead wood or light pruning for shaping. This article focuses on hybrid tea roses which require much more extensive pruning. With hybrid teas, there are three pruning styles, each with a specific purpose. Heavy or severe pruning is done on well-established, vigorous plants to produce large, showy flowers. Prune back to three to four healthy canes with three to six eyes per cane. Canes normally will be 6 to 12 inches long. Moderate pruning is done on well-established, healthy plants and is designed to increase the number of flowers produced rather than increase flower size. Leave five to six healthy canes with at least seven buds per cane. Prune stems to 12 to 18 inches long. Light pruning rejuvenates plants after years of neglect or may be performed on newly established plants. Leave five to seven canes of about 18 inches or more in length. This helps maximize leaf area for energy production and rejuvenates plants.

If your plants suffered a significant amount of winter damage, they may need to be cut back more severely than even the heavy-pruning style. This will result in a few large flowers but in this case is your only option. (Ward Upham)

Ornamentals:
Breaking the Pine Wilt Cycle

Pine wilt disease
Pines have several disease and insect problems. One of them is pine wilt disease. It kills the entire tree quickly.

Pine wilt is caused by the pinewood nematode, a microscopic worm. The nematode is spread by the pine sawyer beetle. The nematode feeds and multiplies in the tree’s resin canals, causing wilting and death in several weeks to several months. The nematode and beetles spend the winter in the infected tree. In spring, the beetles emerge starting around May 1, carrying nematodes to new trees and continuing the cycle of infection.

The disease is common in the eastern half of the state, and it is spreading west around 10 miles per year. There have been pockets of infection in the western part of the state.

In Kansas, new pine wilt infections are most visible from August to December. Trees wilt and die in a short period of time, from several weeks to a few months. In the first stages, the needles turn grey or green, then yellow and brown. The discoloration sometimes occurs branch by branch, sometimes all at once. With pine wilt, eventually the whole tree dies, within a few months. The brown needles stay on the tree for up to a year after the tree has died. Another key symptom is reduced resin. On a healthy tree, sticky resin bleeds from the site of a wound. In contrast, if a tree has pine wilt, the resin is often reduced or absent, and branches become dry or brittle.

There is a website with color photos and descriptions at the following link: http://muextension.missouri.edu/explorepdf/miscpubs/mx0858.pdf

There are images to compare and contrast pine wilt with other pine diseases here: http://www.ksre.ksu.edu/bookstore/pubs/l722.pdf

With the other diseases (tip blight, needle blight) only parts of the tree turn brown. With pine wilt, the whole tree is brown and dead. If you aren’t sure if your tree has pine wilt or something else, contact your local K-State Research and Extension Office or the K-State Diagnostic Lab (clinic@ksu.edu).

If a tree has pine wilt, the tree should be cut down by April 1 to make sure there is time to destroy the wood by May 1, when the beetles start to some out. Cut the tree to the ground—don’t leave a stump. Chip or burn the wood immediately to destroy the beetles and nematodes. Don’t keep pine wood around for firewood. (Megan Kennelly)

Wild Garlic, Wild Onion, and Star-of-Bethlehem

wild garlic
Wild garlic (Allium vineale) and wild onion (Allium canadense) are two closely related plants that can become weed problems in home lawns and landscapes. Though wild garlic and wild onion look much alike, each has an odor that is characterized by its name – wild garlic smells like garlic and wild onion smells like onion. These plants are perennials that can also reproduce by seeds and aerial bulbils. Bulbils form at the top of the stem and are oval and smooth. Wild garlic also reproduces by underground bulb offsets, but wild onion does not. Both species produce a clump of plants that is unsightly in a lawn. Control recommendations are the same though we now have a couple of new additions to our arsenal.

Traditionally we have used 2,4-D or 2,4-D + MCPP + Dicamba (i.e., Trimec, Weed-Out, Weed-B-Gon). These products should be sprayed during March on a day that is at least 50 degrees. Newer products are Weed Free Zone and Speed Zone. Both are combination products that contain a formulation of Trimec plus carfentrazone. These will give a quicker response at cooler temperatures near 50 degrees. A spreader-sticker added to the spray should help any of these products be more effective. At times, the spreader-sticker is already mixed into the weedkiller; no additional amount is needed. These herbicides are also effective on dandelions.

Unfortunately, we have not had a good chemical control for Star-of-Bethlehem. The best products we had were Coolpower (31.3% control) and Turflon Ester (23.8% control). Coolpower is a commercial only product, but Turflon Ester is available to both commercial and homeowner users. But research out of Virginia Tech has improved our outlook. Scientists there did a study in which they gained 96% control of Star-of-Bethlehem one month after treatment by using Quicksilver, a formulation of carfentrazone at the rate of 4 fl. oz/A. Quicksilver is a commercial only product, and therefore is not available to homeowners. However, both Speed Zone and Weed Free Zone contain carfentrazone and would certainly be worth a try if you have this troublesome plant. (Ward Upham)

Contributors: Megan Kennelly, Plant Pathologist; Ward Upham, Extension Associate

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Horticulture Newsletter 2015, No. 10

3/6/2015

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Video of the Week:
Pruning Grape Vines

Vegetables:
Time to Plant Potatoes Approaching

planting potatoes
St. Patrick’s Day is just around the corner, so it is time to get seed potatoes in the ground. Actually any time from mid- to late-March is fine for potato planting. Be sure to buy seed potatoes rather than using those bought for cooking. Seed potatoes are certified disease free and have plenty of starch to sprout as quickly as soil temperatures allow. Most seed potatoes can be cut into four pieces, though large potatoes may yield more, and small less. Each seed piece should be between 1.5 and 2 ounces to insure there is enough energy for germination.

Each pound of potatoes should yield 8 to 10 seed pieces. Cut the seed 2 to 3 days before planting so freshly cut surfaces have a chance to suberize, or toughen, and form a protective coating. Storing seed in a warm location during suberization will speed the process. Plant each seed piece about 1 to 2 inches deep and 8 to 12 inches apart in rows. Though it is important to plant potatoes in March, emergence is slow. It is often mid- to late-April before new plants poke their way through the soil. As the potatoes grow, pull soil up to the base of the plants. New potatoes are borne above the planted seed piece, and it is important to keep sunlight from hitting the new potatoes. Exposed potatoes will turn green and produce a poisonous substance called solanine. Keeping the potatoes covered will prevent this.  (Ward Upham)

Rhubarb

Rhubarb
Rhubarb is a perennial vegetable that can be a bit tricky to grow in Kansas. It is native to northern Asia (possibly Siberia) and so is adapted to cold winters and dry summers. However, it is susceptible to crown rot and should not be subjected to “wet feet” and therefore should be grown in a well-drained soil. The addition of organic matter can increase drainage as well as raise the soil level so that crown rot is less likely.  Also, have a soil test done as rhubarb does best with a pH below 7.0.

Rhubarb should be planted from mid-March to early April in Kansas. Mix 5 to 10 pounds of well-rotted barnyard manure into the soil for each 10 square feet of bed before planting.  Rhubarb is propagated from crowns (root sections) that contain one or two buds. Plants should be spaced 2 to 3 feet apart in the row with 4 to 5 feet between rows. The crowns are planted shallow so that the buds are just one-half to 1 inch below the soil surface. Firm soil around the
crowns and make sure they are not in a depression that holds water. Recommended varieties include Canada Red, Crimson Red, McDonald and Valentine.

Rhubarb needs rejuvenated at least every 5 to 10 years and should be dug and divided in the same time period as new plantings are established. Use a cleaver or axe to cut crowns into sections that each contain one or two buds. Plant as described above.

Newly transplanted rhubarb should not be harvested the first year so the plant can recover from the transplant process. Only a few stalks should be harvested the second year to allow the plant to continue to build up its energy reserves. The harvest season for plants that are three years or older usually lasts about 8 weeks. Harvest only the largest and best stalks by pulling them slightly to the side so that they break away from the plant. Never harvest over one-third of the leaf stalks at one time. Only the leaf stalk (petiole) is eaten as the leaf blade contains oxalic acid and is poisonous.

Mulches can be used to reduce moisture loss, prevent weed growth and provide winter protection. However, it should be pulled away in the spring to allow the soil to warm so that early growth is encouraged. (Ward Upham)

Fruit:
Pruning Raspberries and Blackberries

Pruning berry canes
Raspberries and blackberries are perennial plants with biennial canes. In other words, a single plant will last many years but an individual cane will only live for two. In a cane’s first year, it will grow but will not produce fruit. The second year, it will fruit and then die. Though these canes can be removed after they have finished fruiting, many gardeners wait until now to remove them.

Dead canes are not difficult to identify. They are a much lighter color than live canes and are dry and brittle. These canes should be removed and discarded. The remaining canes should be thinned but the type of growth determines exactly how this should be done.

Black and purple raspberries and thornless blackberries tend to grow in a clump. Remove all the canes but 5 to 7 of the largest and healthiest in each clump. Cut back the remaining canes to living tissue if there was winter damage. Thornless blackberries will also produce a few suckers that come up some distance from the clump. These should be removed or dug and transplanted to increase the planting.

Red raspberries and thorny blackberries sucker badly and will fill the row with new plants.  Prune out small canes within the row so that there are strong canes 4 to 6 inches apart. Head back all the remaining canes to about 5 feet. Keep aisles free of new suckers during the summer by mowing.        

We now have what is called ever-bearing red raspberries and everbearing thorny blackberries.  These are the exception to the rule in that they will bear fruit on first-year canes. Therefore, you can cut all canes to the ground in the winter and still have fruit. Examples include Heritage red raspberry and Prime-Jim, Prime-Jan and Prime Ark 45 blackberries.

For more detail and line-drawings that illustrate pruning techniques, see our publication titled, “Raspberries and Blackberries” at http://www.ksre.ksu.edu/bookstore/pubs/mf720.pdf. (Ward Upham)

Turfgrass:
Managing Turf in Shade

turfgrass in the shade
Turfgrasses differ in their capacity to grow in shade. Among Kansas turfgrasses, tall fescue is the best adapted to shade though it isn’t all that good. Although the fine fescues (i.e., creeping red, chewings, hard and sheep) have better shade tolerance, they lack heat tolerance and typically decline during hot Kansas summers. The warm-season grasses have the poorest shade tolerance, although zoysia does better than Bermuda or buffalo.

Where shade is too heavy for fescue, there are other courses of action. The most obvious is to either remove trees, or to prune limbs and thin the tree canopies. Grass will do better under openly spaced trees than under closely spaced trees. Pruned limbs and thinned canopies will allow more sunlight to directly reach the turfgrass. If possible, raise the mowing height in the shade to compensate for the more upright growth of the leaves, and to provide more leaf area for photosynthesis. The thin, weak turf in the shade may tempt you to fertilize more. Remember the problem is lack of light, not lack of fertility. Too much nitrogen in the spring causes the plant to grow faster and may result in weak plants. The nitrogen rate for shaded grass should be cut back to at least half of that for grass in full sun. Late fall fertilization after tree leaves have fallen, on the other hand, is important for shaded cool-season turfgrasses and should be applied at a full rate. Irrigate infrequently but deeply. Light, frequent irrigation may encourage tree feeder-roots to stay near the surface, which increases competition between the trees and the turf. Restrict traffic in the shade.

Many times, the best choice for shaded areas is switch from a turfgrass to a more shade-tolerant plant. For example, English ivy and periwinkle (Vinca minor) are much more shade tolerant than any turfgrass adapted to our area. Another option is simply to mulch the area where turf doesn’t grow well. The trees will love the cool, moist soil and the absence of competition. (Ward Upham)

Ornamentals:
Ten Rules for Planting Trees

planting a tree
Before you begin spring landscaping, here are some tips on planting trees.

1. Select the right tree for the site. To avoid serious problems, choose trees that are adapted to your location. Consider whether the tree produces nuisance fruit or if there are disease-resistant varieties available. For example, there are a number of crabapple varieties that are resistant to apple scab and rust diseases. Also consider the mature size of a tree to be sure you have enough room. See http://www.hfrr.ksu.edu/p.aspx?tabid=731  or ask a local nurseryman for suggestions.

2. Keep the tree well watered and in a shady location until planting. When moving the tree, lift it by the root ball or pot and not by the trunk.

3. Before planting, remove all wires, labels, cords or anything else tied to the plant. If left on, they may eventually girdle the branch to which they are attached. The root flare (point where trunk and roots meet) should be visible. If it isn't, remove enough soil or media so that it is.

4. Dig a proper hole. Make the hole deep enough so that the tree sits slightly above nursery level.  Plant the tree on solid ground, not fill dirt. In other words, don't dig the hole too deep and then add soil back to the hole before placing the tree. The width of the planting hole is very important. It should be three times the width of the root ball. Loosening the soil outside the hole so it is five times the diameter of the root ball will allow the tree to spread its roots faster.

5. Remove all containers from the root ball. Cut away plastic and peat pots; roll burlap and wire baskets back into the hole, cutting as much of the excess away as possible. If you can remove the wire basket without disturbing the root ball, do it. If roots have been circling around in the container, cut them and spread them out so they do not continue growing so that they circle inside the hole and become girdling roots later in the life of the tree.

6. Backfill the hole with the same soil that was removed. Amendments such as peat moss likely do more harm than good. Make sure the soil that goes back is loosened - no clods or clumps.  Add water as you fill to insure good root to soil contact and prevent air pockets. There is no need to fertilize at planting. Note: Adding organic matter to larger area than just the planting hole can be beneficial, but it must be mixed in thoroughly with the existing soil. However, adding amendments to just the planting hole in heavy soil creates a “pot” effect that can fill with water and drown your new tree.

7. Don't cut back the branches of a tree after planting except those that are rubbing or damaged. The leaf buds release a hormone that encourages root growth. If the tree is cut back, the reduced number of leaf buds results in less hormone released and therefore fewer roots being formed.

8. Water the tree thoroughly and then once a week for the first season if there is insufficient rainfall.

9. Mulch around the tree. Mulch should be 2 to 4 inches deep and cover an area two the three times the diameter of the root ball. Mulching reduces competition from other plants, conserves moisture and keeps soil temperature closer to what the plants' roots prefer.

10. Stake only when necessary. Trees will establish more quickly and grow faster if they are not staked. However, larger trees or those in windy locations may need to be staked the first year.  Movement is necessary for the trunk to become strong. Staking should be designed to limit movement of the root ball rather than immobilize the trunk. (Ward Upham)

Miscellaneous:
Adding Organic Matter in the Spring

adding organic matter to soil
Organic matter is a good way to improve garden soil as it improves a heavy soil by bettering tilth, aeration and how quickly the soil absorbs water. However, organic matter added in the spring should be well decomposed and finely shredded/ground. Manures and compost should have a good earthy smell without a hint of ammonia. Add a 2-inch layer of organic matter to the surface of the soil and work the materials into the soil thoroughly. Be sure soils are dry enough to work before tilling as wet soils will produce clods. 

To determine if a soil is too wet to work, grab a handful and squeeze. If water comes out, it is much too wet. Even if no water drips out, it still may not be dry enough to work. Push a finger into the soil you squeezed. If it crumbles, it is dry enough, but if your finger just leaves an indentation, more time is needed. Be sure to take your handfuls of soil from the depth you plan to work the soil because deeper soils may contain more moisture than the surface.  (Ward Upham)

Contributors: Ward Upham, Extension Associate

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Horticulture Newsletter 2015, No. 9

3/2/2015

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Video of the Week:
Growing Asparagus

Vegetables:
Bolting and Buttoning in Cole Crop Plants

Broccoli plant
Broccoli, cabbage and cauliflower are cole crops that have a tendency to bolt (go to seed) or button (produce an extremely small head) if plants are not grown properly. These crops need to be kept actively growing through their production cycle, including growing transplants from seed. If they slow down due to under-fertilization or are stunted due to overgrowing their container, buttoning or bolting is more likely. If you are not growing your own transplants but rather selecting plants from a retailer, choose small, stocky dark green plants.

Even after transplanting, these plants need to be well-fertilized. Fertilize at transplanting with a starter solution and continue to fertilize every 2 to 3 weeks until harvest. Both buttoning and bolting are irreversible. Once a seed stalk starts for form, nothing can be done to force the plant to produce a normal crop. (Ward Upham)

Fruit:
Strawberry Mulch Removal

Picture
Research done in Illinois has shown that the straw mulch should be removed from strawberry plants when the soil temperature is about 40 degrees F. Fruit production drops if the mulch remains as the soil temperature increases. There are likely to be freezing temperatures that will injure or kill blossoms, so keep the mulch between rows to conveniently recover the berries when freezing temperatures are predicted. (Ward Upham)

Flowers:
Fertilizing Perennial Flowers

Perennial plant emerging
Most flowering perennials are not heavy feeders, and once established, may not need fertilizing every year. However, a soil test or visual symptoms will help determine plant needs. Weak plants with light green to yellowish foliage will probably benefit from a nitrogen-containing fertilizer. In the absence of a soil test, apply a 10-10-10 or similar fertilizer at the rate of 1 pound per 100 square feet.

Fertilizer should be applied as growth begins in the spring. Perennials that tend to need more fertilizer than the average perennials include astilbe, chrysanthemum, delphinium, lupines, and summer phlox. A second application during summer may be helpful for these plants. (Ward Upham)

Ornamentals:
Seven-son Flower

SEven-son shrub
This large shrub is finally starting to receive the recognition it deserves.  A native of China, seven-son-flower was first collected in 1907, named in 1916, and then languished in obscurity.  Another expedition to China in 1980 resulted in a collection of viable seeds that were propagated and distributed to several botanical institutions and nurseries.  Over the years, it has slowly become more widely planted. 

Numerous characteristics contribute to the attractiveness of this plant.  Leaves are a dark, glossy green and are rarely bothered by pests.  Creamy, white flowers appear in late summer when few plants are in bloom.  The inflorescence is distinctive in arrangement and effect.  Though each individual flower is quite small, they are borne in a panicle with six flowers tiered in a whorl with the seventh terminating the inflorescence.  Panicles are born on the tips of branches. 

After the flowers fade, fruit appears with surrounding sepals.  Color changes from green to red and persists for 2 to 3 weeks.  This plant is actually more attractive in this post-bloom period than in flower. 

Though often grown as a large shrub, Seven-son Flower can be trained as a small tree and reach 15 to 25 feet in height.  Exfoliating (peeling) bark is attractive with the inner bark being lighter. Hardy to Zone 5, seven-son flower prefers moist, well-drained soils.  (Ward Upham)

Cut Back Ornamental Grasses

cutting ornamental grass foliage
March is a good time to remove dead foliage from ornamental grasses. Grasses green up earlier if foliage is removed and are more attractive without a mixture of dead and live leaves. A number of tools can be used including hand clippers, weed whips (if the foliage is of a small enough diameter), weed whips with a circular blade, or even a chain saw. Use the top of the chainsaw bar to cut so the saw doesn’t pull in debris and clog. Also, it is often helpful to tie foliage together before cutting so it doesn't interfere and is easier to dispose of. Burning is another option — but only if it is safe and legal to do so. Note that these grasses may not burn long, but they burn extremely hot. Even so, the crown of the plant is not damaged and new growth appears relatively quickly.

If the center of the clump shows little growth, the plant would benefit from division. Dig up the entire clump and separate. Then replant the vigorous growth found on the outer edge of the clump. (Ward Upham)

Pruning Deciduous Shrubs

shrub before pruning
shrub after pruning
Gardeners are eager to get out and do something in the landscape this time of year. One chore that can be taken care of during March is pruning certain shrubs. Often, gardeners approach pruning with trepidation, but it is not as difficult as it may seem. Remember, not all shrubs need to be pruned (i.e., witch hazel), and certain shrubs, which will be identified later in this article, should not be pruned this time of year. Shrubs are pruned to maintain or reduce size, rejuvenate growth, or to remove diseased, dead or damaged branches. Deciduous shrubs are those that lose leaves each winter. Evergreen shrubs maintain foliage all year and include yews and junipers.

Deciduous shrubs are placed into three groups:
        • Those that flower in the spring on wood produced last year;
        • Those that flower later in the year on current seasons’ growth; and
        • Those that may produce flowers, but those flowers are of little ornamental value.

Shrubs that flower in the spring should not be pruned until immediately after flowering. Though pruning earlier will not harm the health of the plant, the flowering display will be reduced or eliminated. Examples of these types of plants include forsythia, lilac, flowering quince, Vanhoutte spirea, bridal wreath spirea and sweet mockorange. Shrubs that bloom on current seasons’ growth or that do not produce ornamental flowers are best pruned in March. Examples include Rose-of-Sharon, pyracantha, Bumald spirea, and Japanese spirea.

Pruning during the spring allows wounds to heal quickly without threat from insects or disease.  There is no need to treat pruning cuts with paints or sealers. In fact, some of these products may slow healing.

There are three basic methods used in pruning shrubs: thinning, heading back, and rejuvenating.   Thinning is used to thin out branches from a shrub that is too dense. It is accomplished by removing most of the inward growing twigs by either cutting them back to a larger branch or cutting them back to just above an outward- facing bud. On multi-stemmed shrubs, the oldest canes may be completely removed.  Heading back is done by removing the end of a branch by cutting it back to a bud and is used for either reducing height or keeping a shrub compact. Branches are not cut back to a uniform height because this results in a "witches-broom" effect.

Rejuvenation is the most severe type of pruning and may be used on multi-stem shrubs that have become too large, with too many old branches to justify saving the younger canes. All stems are cut back to 3- to 5-inch stubs. This is not recommended for all shrubs but does work well for spirea, forsythia, pyracantha, ninebark, Russian almond, little leaf mock orange, shrub roses and flowering quince. (Ward Upham)

Contributors: Ward Upham, Extension Associate
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    Authors

    Ward Upham runs the Horticulture Response Center in the Department of Horticulture and Natural Resources at Kansas State University. Other contributors include K-State Extension Specialists.

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