Horticulture 2023 Newsletter No. 11 

KSRE - Division of Horticulture



Blog Post: http://www.ksuhortnewsletter.org

Video of the Week: How to Plant a Tree

1. Plant peas
2. Cut back ornamental grasses.
3. Plant potatoes

Important Announcement: As many of you know, I am on phased retirement. One of my main concerns with my upcoming retirement next February is whether we would have someone to replace me. I was extremely pleased that we were able to hire one of our former graduate students, Cynthia Domenghini. She will continue the newsletter as well as run the Horticulture Resource Center (https://hnr.k-state.edu/extension/horticulture-resource-center//). She will also develop online courses for the department. You will note that she will be contributing to our newsletter each week. You can reach Cynthia at [email protected] . Please welcome her. (Ward Upham)

Asparagus is a perennial vegetable with three primary parts: the fluffy top is called the fern; the crown is the part just beneath the soil and the roots extend down from the crown. Each spring new edible spears (stems) emerge from the crown. To promote growth this season, last year’s stems and ferns needs to be removed now.
Old spears and ferns can be removed by hand or by gently tilling or mowing, using caution not to damage the crowns. Burning is another option if it is safe and legal to do so.
Asparagus spears emerge from early to mid-April in Manhattan but earlier in southern Kansas and later in northern Kansas.
Fertilize asparagus after the harvest, as needed, based upon a soil test. General recommendations are to apply 1 to 2 pounds of 10-20-10 or 11-15-11 fertilizer per 20 feet of row. If only nitrogen is needed, apply 1 pound of 16-0-0 or ½ pound of 30-4-5, 27-3-3 or similar fertilizer per 20 feet of row. Most of these high nitrogen fertilizers are lawn fertilizers but can be used for this crop as long as they don’t contain a weed preventer or killer. Water in the fertilizer application with ¼ inch of water. (Cynthia Domenghini)

Controlling Weeds in Home Garden Asparagus Beds
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 as well. 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 glyphosate (Roundup) to control virtually all of the weeds present. After the harvest season is past and the asparagus starts to regrow, options are limited. Products that contain sethoxydim can be applied to asparagus to kill annual grassy weeds such as crabgrass. 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)

Help for Vegetable Gardeners

Kansans that are new to vegetable gardening often don’t know how much of each crop to plant. K-State Research and Extension has a publication that can help. The “Vegetable Garden Planting Guide” gives information on the size of planting needed per person and the average crop expected per 10 feet. Also included is a garden calendar highlighting suggested planting dates and expected harvest dates. Crop specific information is detailed including days to germinate, plants or seeds needed per 10 feet of row, depth of planting, spacing within the row and spacing between rows. You can find the publication at your local county extension office or online at: http://www.ksre.ksu.edu/bookstore/pubs/mf315.pdf . If you don’t know the location of your county extension office, see http://www.ksre.ksu.edu/Map.aspx.
Another, more in-depth publication titled the “Kansas Garden Guide” is also available. Newly updated, this 202-page publication has sections on planning a garden, composting, improving soil, seeding and planting, garden care, watering, planting gardens for fall production, insect and disease control, container gardening, season extension and harvesting and storing. This is followed by an extensive section on how to grow specific vegetables and herbs. You may access a free PDF copy of this publication at http://www.ksre.ksu.edu/bookstore/Item.aspx?catId=534&pubId=8219 . A “for pay” print copy will be provided in the future. Check the above link for availability of the print copy and price. These publications can also be useful for experienced gardeners. (Ward Upham)

Winter Damage to Woody Plants
We are again seeing winter damage to various woody plants, especially semi-evergreen shrubs such as Manhattan euonymus and boxwood. Normally this kind of damage is caused by a sharp drop in temperature after a warm fall. However, though we did go through the drop in temperature, we also had a very dry fall making damage more likely.
On campus, itt appears most of the damage was done to the leaves with buds not being harmed. This will mean these plants should put out new leaves and be fine in the Manhattan area IF they had sufficient soil moisture.
The Wichita area had less rain than we did and also had a more sharp drop in temperature. They ae noting damage not only on the shrubs mentioned above but also on pachysandra, aucuba, viburnum, live oak, English ivy, wintercreeper euonymus, blue atlas cedar and various other evergreen and semi-evergreens. We will likely see more damage appear as spring progresses.
The best time to assess the extent of the damage and the potential for recovery is mid May. By this time, new growth should have developed and it will be clear if the buds are going to put on some new growth. You can also check for potential recovery by pulling off a few buds. If they are brown inside, don’t expect any new growth. If the buds are green inside, the plant may put on some new growth
So what can you do now? Water trees and shrubs if the soil is dry. For information on methods to water trees and shrubs, see https://www.ksuhortnewsletter.org/newsletters/inexpensive-method-of-watering-trees1505104
(Ward Upham)

Brown Coloration on Junipers
Certain eastern redcedar and various other junipers are showing a brownish cast when viewed from a distance. This may be the male flowers. Male flowers are on the tips of the leaves and look somewhat like a cross between a miniature hand grenade and a pinecone. Shaking the branches on dry days will often result in a cloud of pollen being released.
Most junipers are dioecious, meaning they have both male and female plants. About half the junipers (the males) will have this coloration. The female flowers are much less obvious. If you have clients who are concerned about this brown coloration, have them check the plants to ensure the male flowers are the cause. If they are, assure them that this is normal and will fade with time. (Ward Upham)

Ten Rules for Planting Trees
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 https://hnr.k-state.edu/extension/info-center/recommended-plants/index.html or ask a local nurseryman for suggestions for trees adapted to your area.
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 before planting 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 fluff 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 ensure 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 and should “feather out” toward the outside edge of the area. This should be done before the planting hole is dug. 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)

Frost Tolerance of Apricots and Peaches
Growers of apricots and peaches often wonder at what temperature fruit buds are killed especially in years where we have an early spring. 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.
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

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 but the material should reach the ground so that heat given off from the soil is captured. Old-fashioned Christmas lights distributed through the tree will help to give added 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 and access to electricity.
Sprinkling the tree with water throughout the freezing period can also protect the blossoms but is a dangerous option. 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)

Managing Turf in 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 fescues) have better shade tolerance, they lack heat tolerance and typically decline during hot Kansas summers. The warm-season grasses have poorer shade tolerance than cool-season grasses, although zoysia does better than Bermuda or buffalo. Where shade is too heavy for fescue, there are other courses of action. The most obvious but often impractical option 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.
Another option is to reseed areas with heavy shade each fall. The turf will look good during the fall and spring and then likely fall apart when the stresses of summer hit.
None of these options is very attractive. This is one of those problems in which there is not a good answer. Many times, the best choice for shaded areas is switch from a turfgrass to a more shade-tolerant plant. For example, periwinkle (Vinca minor) is 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)

Cynthia Domenghini, Instructor
Ward Upham, Extension Associate

Division of Horticulture
1712 Claflin, 2021 Throckmorton
Manhattan, KS 66506
(785) 532-6173

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