This is the Q&A for the Yard and Garden show for May 15, 2020. 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 31, 2020. 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: No guest host due to COVID-19 and social distancing
1. The first caller of the show wants to know how to plant the flowering plants he received from the Lower Big Blue NRD in Beatrice on the show last week? How far apart to space them and what type of growing environment should they be planted in?
A. Give the plants plenty of space, they are all large shrubs or small trees. The selection included Nanking cherry, redosier dogwood, lilac, crabapple, and caragana. They all need at least 8 feet of width and height. They all take full sun, but the redosier or red twig dogwood can take part shade. They could be planted on the interior of a windbreak to add to it or throughout a landscape.
2. A caller received a hydrangea plant as a gift for Mother’s Day. The flowers are now droopy. Should it be planted outside or what can be done to improve the flowers?
A. Yes, plant it outdoors. It can be planted in a container, but that would need to be protected over the winter months. Otherwise, plant it outdoors in part sun. The plant may also be finishing up the bloom period for this year, so remove those spent blossoms when they begin to turn brown.
3. This caller has iris borer. Should she dig up the plants now to remove the highly infected, mushy areas?
A. Leave them for now but clean out the mushy rhizomes as much as you can and spray the plants with an imidacloprid product to kill the larvae. Dig up the plants in the fall and clean them out. Next spring spray the plants earlier to prevent more damage. Also, be sure to clean off the dead leaves in the fall, this will destroy their overwintering location.
4. A caller has strawberries with a leaf spot disease. What can be done with them? He is already harvesting.
A. To prevent further spread and reduce diseases in the future, use soaker hoses to water rather than watering over the top of the plants. Also, make sure you have mulch around the plants which can also help reduce the spread of diseases. Captan can be used through the season for leaf spot disease. Spray every 10 days through the season, next year start before they begin to bloom. Be sure to follow the PHI listed on the product for strawberries. The PHI is the Pre-Harvest Interval, the amount of time to wait after applying a chemical before harvesting.
5. A caller has cedar-apple rust on his cedars that is harming them and causing the branches to turn orange. What can he do for it?
A. Cedar-apple rust is not damaging to cedar trees. If the branches are becoming covered in orange, it could be cedar-quince rust which can cause problems on cedar trees. You can spray the trees with Captan, Daconil, or Mancozeb to treat cedar-quince rust.
6. This caller has beans and popcorn that was planted from seed a while ago but it has not sprouted yet. Why is that?
A. It has been too cold for them yet. The soil temperatures are hovering just below 60 degrees and most of our warm season plants need at least 60 degree soil temperatures to grow well. Give them time, they should sprout in the next week or so as the weather warms up more.
7. A caller has Elephant Ear that was in the garage over the winter. She planted it in a lick tub before the last weekend with the cold temperatures. It has not yet sprouted, will it be ok or is it likely done?
A. It is still quite chilly for something like an elephant ear. Even though the plant had not yet emerged before the frost events last weekend, the lick tub may not have protected it enough since it is a bulb that needs to be dug up every year. Give it time, it might be ok though. It is hard to tell for sure yet.
8. This caller has wild violets in her yard. She had it treated twice in the fall and they are still coming up. What can be done about that?
A. Wild violets are very difficult to manage. They cannot be eliminated in a single treatment or even in multiple treatments in one year. It will take time and reapplications to really knock them back. 2 applications in the fall will be most effective. Apply a 2,4-D product in mid-September and again in mid-October for best control. Because we don’t know when the lawn was sprayed, or exactly what was spryed on it, it is hard to tell for sure why the plants are still so bad. Diligence with this plant would be best.
She also wanted to know how to control nutsedge in her lawn.
A. Nutsedge can be controlled with a sedge-specific chemical such as sedgehammer or sedge ender among others. Apply these chemicals before the longest day of the year, June 21st, to help reduce the population for next year. It isn’t a preemergence herbicide, but it will reduce the growth for future seasons.
Her final question was how to control weeds through the summer in an area that she has planned to overseed this fall?
A. Keep mowing the area will help reduce the flower and seed production through the year. She can continually spray roundup on the area throughout the summer to keep them down as well. Spray the Roundup 2 weeks ahead of overseeding to help kill it off before planting. She could use mesotrione, found in Tenacity, at seeding to help with weeds and not harm the seeding.
9. Why are the peonies not blooming yet?
A. With all of the cold weather we have had, it has slowed the growth of plants such as peonies. They are behind their normal blooming time for the year due to the snow and frost so late this spring. Give them time to flower a little later. They likely will not bloom by Memorial Day this year because of how cold it has been this spring. However, depending on the stage of development of the flowers when the snow and frost occurred, the blooms may have been damaged and may not open up this year. Give the plants time to recover into mid-June before giving up on the blossoms.
10. This caller is trying to grow rhubarb. It will start growing in the spring but then just stops growing larger and isn’t getting very large stalks. What is the problem?
A. It might be good to try a soil test to see how the soil nutrient levels and pH are where the plants are growing. You could try some fertilizer to help it grow larger. These plants were purchased from a flea market, from another grower, it might be that the plants were older and maybe not as productive. Try to start a new patch with new plants purchased from a nursery or garden center.
11. A caller has linden trees that had a problem with Japanese beetles last year. What can be done to control them this year?
A. After they have finished blooming, the trees can be sprayed with bifenthrin or chlorantraniliprole. Make sure you can get to the top of the tree for best control. He may need to call an arborist to spray the trees more thoroughly. Treating the yard for grubs can help. Don’t put a trap in your yard, this just brings more in from the surrounding locations.
12. This caller is wondering why her iris’ are not blooming? The plants of the same variety are blooming on one side of her house but not the other. Why is that?
A. The cooler weather is causing many of our plants to slow down or not bloom when they normally would be blooming. If the iris are blooming on one side of the house and not the other, and they are the same variety, this could be due to the microclimate on the sides of the house. One side may warm up sooner in the day causing those plants to warm up more and bloom sooner. Maybe the wind is hitting the one side more causing those plants to stay cooler longer. Give them time, they should all bloom eventually.
She also wondered why her celery is yellow. Is it due to the cold damage or is she overwatering?
A. It could be due to the cold weather. She is watering every other day for 2 hours per day with a sprinkler, this could be too much water. Monitor how much water is actually applied during that time by using a catch can. Vegetable gardens need about 1 inch of water per week. I would assume this celery is getting more than that.
13. Why are there so many seed stalks in the rhubarb plants this year?
A. The cold temperatures this spring are unusual and have “confused” the plants. This has pushed the plants to produce seed stalks. When rhubarb plants begin to produce seed stalks they push their energy into seed production and not into leaf and stalk production. To push that energy back into the stalk production we desire from rhubarb, cut the seed stalks off of the plant.
14. The final caller of the day has onions that are turning white and falling over. He didn’t cover them in the freezing weather last weekend. Is it cold weather injury that is causing this damage?
A. It is likely that this is from the cold temperatures. Even onions can be injured by temperatures in the low 30’s like what we saw. If there is green in the lower leaves, they might regrow.
*Reference to commercial products or trade names does not imply endorsement by Nebraska Extension or bias against those not mentioned.