This is the Q&A for the Yard and Garden show for March 31, 2017. Yard and Garden Live is a call-in radio show I do on KUTT 99.5 FM from 10-11:30 am and it will run through July 28, 2017. It can also be found on kutt995.com for online listening. If you missed a show or just want to read through the questions, I have written them all in my blog and will continue to do so throughout the season.
Guest Host: Natalia Bjorklund, Nebraska Extension Educator in Dodge County
1. The first question was when can we begin applying crabgrass preventer and fertilizer to our lawns this spring?
A. These are both best applied in late April to early May. Crabgrass will not germinate until the soil temperatures are consistently at 55-60 degrees Fahrenheit.
2. A caller wanted to know if he should mulch his asparagus and if he can use ash wood mulch around his asparagus?
A. Yes, mulch is one of the best ways to manage weeds in an asparagus patch. Ash wood chips would be fine. You do want to avoid Walnut wood chips because walnuts produce juglone which is a chemical produced by the tree to act as a weed control for nearby plants. This helps walnut trees with competition in the wild.
3. This caller has a goldenrod that has grown too large and messy for the area where it is planted. How can it be killed and what Goldenrod would be a better choice for a less messy plant?
A. 2,4-D or simple hand removal should kill the plant. When purchasing a Goldenrod plant in the future, any of the varieties would be better than the straight species. Fireworks is a nice, open goldenrod. Wichita Mountains and Baby Blue would be good choices as well.
4. Is it too early to transplant hostas? When should you cut back warm season grasses?
A. Wait a couple of weeks to transplant the hostas until the soil has warmed up a little more. You can cut back the ornamental grasses anytime now. It is better to get the old growth cut off before growth resumes so you don’t cut off the new growth. For ease of cleanup with the ornamental grasses, wrap string or twine around the plant before cutting off the old materials so it stays together when taking to the compost pile.
5. A caller wanted to know how and when to prune roses?
A. Wait until a little later into April to start pruning them. It depends on the type of rose to know how to prune them. This sounds like a climbing rose which can be pruned back about 1/2 to reduce the size. Wait until they start greening up to know which areas of the canes have died back, the dieback should be removed as well. If the canes are long and lean over mowing areas or other things, they can be tied up to a trellis.
6. This caller wanted to know how to get rid of cockleburs?
A. While talking with the caller, it came up that the plant had very small yellow flowers on it and there were spines over the plant except right at the soil surface. This plant is in fact buffalobur, not cocklebur. These are easily pulled up if you pull where there are no spines. A 2,4-D product could also be used if there was a large amount of them in the lawn.
Buffalobur plant from Howard F. Schwartz, Colorado State University, Bugwood.org
7. A caller wanted to know if they should water in their crabgrass control?
A. The label will explain to you how a product should be applied for best efficacy. Always read and follow the label instructions to apply correctly. For many of the crabgrass preventers, they would need to be watered in, but again, check the label to be sure.
8. When should asparagus be fertilized?
A. Apply a general fertilizer or a composted manure to the bed after the last harvest or sometime in the fall.
9. This caller has mulberries growing in the windbreak. After they are cut down, what kind of stump treatment should be done to keep them from regrowing?
A. 2,4-D concentrate should be used as a stump treatment. This will take multiple applications and will be more effective if done in the fall. Each time the 2,4-D is reapplied it should be applied into newly drilled holes or to a freshly cut area of the stump.
10. A caller has cedars growing in their landscape. Under the cedars there is bare ground. What can they plant in that area to avoid weeds coming in?
A. The cedars are going to keep that area quite dark and the cedars will take the majority of the water in the soil so mulch would be a good alternative. If plants are desired, use a shade tolerant groundcover such as wintercreeper or vinca vine or perennial plants such as bleeding hearts, hostas, coral bells, jacob’s ladder, and others.
11. This caller has tiny cedar trees coming up throughout the lawn. How can they be controlled?
A. Cut them off at ground level. If a cedar is cut below any lateral growth it will not regrow. Mowing over them wouldn’t be low enough.
Proper pruning cut, University of Missouri Extension
12. When is the best time to prune a maple tree that had a branch break in a storm?
A. As soon as the storm has passed and it is safe to do so, you should remove a branch that broke in the storm. If the damage occurred in a winter storm, let the ice and snow melt off first. Then, hire a certified arborist to come out and make a good pruning cut so that the tree can seal off the wound quickly and fully.
13. A caller has a hibiscus tree that is turning yellow and many of those yellow leaves are falling off the tree. It was moved indoors during the winter months in an area of the house with low sunlight. What is wrong with it and will it survive?
A. Hibiscus plants would need more sunlight than what it has received through the winter. It should be fine once it gets more sunlight. As the days get warmer, you can move it outdoors for more intense sunlight. It should be fine once it gets moved to better growing conditions.
14. This caller has a weeping willow tree that they would like to prune up a little. When can they prune it?
A. The weeping branches shouldn’t be pruned up too much or they could lose their weeping habit. Willows tend to have a heavy sap flow in the spring if they are pruned then, so it would be best to wait until later fall to prune a willow.
15. This caller has grasses that are coming up among the gravel paths around his daylily patch. What can he use to prevent those plants from coming up?
A. Preen is a great way to stop the germination of annual weeds, such as many of our weedy grass species. If they come up before the preen gets put down or if they grow as a perennial weed, you can use a post-emergent herbicide. If it is a grass that is growing out of place among daylilies, you can use Grass-B-Gon or a similar product to kill grasses.
Photo of henbit is from Steve Dewey, Utah State University, Bugwood.org
16. What can be done to manage henbit?
A. At this time of the year, there is nothing very effective at controlling henbit. Henbit is a winter annual plant, meaning that it germinates in the fall and flowers and produces seed in the spring. It dies with the summer heat. As we are now seeing the purple flowers from henbit, there is no need to control what you are seeing. The seed is already present in the lawn for next year and what you would be spraying will die soon. You can hand pull it now and spray with a 2,4-D product late in the fall.
17. This caller has moon flowers that had a lot of hornworms on them last summer. What can be done this year to reduce the number of hornworms?
A. Just because there were hornworms there last year doesn’t necessarily mean you will have a lot this year. Hornworms are sporadic pests. They are easily controlled by hand removal. You can also use sevin or eight or any other general insecticide. Use Bt to protect other pollinators as Bt is only harmful to insects in the order Lepidoptera which includes butterflies and moths.
18. What do you do for bindweed in a vegetable garden?
A. If you haven’t planted yet this spring, you can roundup the plants before you prepare the soil for the summer vegetables. The plants will probably still be a problem later in the year as this is a difficult pest to control. When it comes back in the summer, you can carefully use roundup through the growing season. You can paint the glyphosate product onto the leaves of the bindweed avoiding spraying the desired plants.