This is the Q&A for the Yard and Garden show for April 10, 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 asked when the best time is to transplant peonies?
A. The best time is in the fall. They can be done in the spring though, as well. You may want to mark the depth that they are planted at currently to ensure they get planted at the same depth at the new location. Use some masking tape or some other way to mark their depth now. If peonies are planted too deep, they will not flower.
2. A caller has Austrian pines that started turning brown last year. He was told to spray them with a copper fungicide in the spring, is that correct?
A. This sounds like dothistroma needle blight which is common on Austrian Pines and Ponderosa Pines. This disease will cause the tree to turn brown, typically from the bottom up with brown bands on the needles upon closer inspection. Needle blight is best controlled with 2 applications of copper fungicide, one in mid-May when the new needles have emerged to about half their size and a second application in mid to late June.
He also asked if he can plant asparagus now?
A. Yes, asparagus is a spring plant. It can be planted in April or May. Asparagus should be planted in a trench 6-8 inches deep. The recommendation has always been to cover the crowns with 2 inches of soil at first and wait until they emerge to continue to add 2 inches of soil each time until the soil level is even with the surrounding soil. However, research shows that this isn’t necessary. The asparagus should still be planted in a trench 6-8 inches deep, but it can be completely covered back up right away to still be successful.
3. Is there any herbicide that can be used to control weeds in a pumpkin patch?
A. Unfortunately, the majority of these herbicides for use in pumpkins are restricted use and can only be purchased and used by individuals with a pesticide applicator license. For a general backyard pumpkin patch, mulch will be your best option to manage the weeds before they become established. Hand pulling through the season will help as well.
4. This caller had planted spinach and radish a few weeks ago. They had emerged and then were covered with snow and ice last week. Now the tops have burned off entirely. Will they regrow?
A. Unfortunately, if the entire tops of these plants were killed with no green showing, they will not likely regrow. You can wait a week or so to see if they regrow, but it may be time to replant these crops. If they were small they don’t have very much for reserves left in the roots to get new growth back.
He also has asparagus growing but it is continually very spindly. What can be done about that?
A. When asparagus is small and spindly, it may need some fertilizer to help it grow thicker, larger stalks. A general garden fertilizer can be used now, in the spring or a manure or other type of fertilizer can be used in the fall.
5. A caller has a 7 year old peach tree and very old apricot trees that are in full bloom right now. With the freezing temperatures predicted for the next several days, will they produce fruit this year?
A. It is not likely that they will survive these freezing temperatures at the stage they are at. Temperatures are predicted to be in the low 20’s for several nights starting on Sunday. According to research by MSU, apricots in full bloom will have 10% blossom kill at 27 degrees and 90% blossom kill at 22 degrees. Peaches in full bloom will have 10% blossom kill at 27 degrees and 90% blossom kill at 24 degrees. If we can stay a little warmer, at that 27 degree mark you should still see a good fruit set this year, but if we do get the cold temperatures predicted it is not likely to have much of a crop. To see more scenarios and more fruits, visit the Spring Freeze Damage Thresholds Guide.
6. This caller had broccoli growing in her garden. The foliage was burned by frost, but she had planted the plants in a tin can with the bottom cut out placed in the soil and placed a bucket over the plants during the cold nights. Will the plants survive?
A. There is still green in the stems, so they should come back. Give the plants a week or so to determine if new leaves emerge. If they don’t put on new leaves in the next week, it is likely that they won’t survive and need to be replanted. Broccoli can take temperatures down to 26-31 degrees, so they should have been ok. You will want to make sure that the plants are covered again, overnight, for the next few days while more cold temperatures are predicted. The predicted temperatures are lower than what the broccoli can survive under normal growing conditions.
7. Is it too late to plant peas? Can tomatoes be planted now?
A. The peas are ok to be planted now, but it might be a good idea to wait until after this next week when the temperatures are to get very cold overnight. Peas can only take temperatures down to 31 degrees. Tomatoes are a warm season crop and shouldn’t be planted until the beginning of May. If planted in a wall-of-water or other protective method, they can be planted in late April. I wouldn’t push the plants too much earlier than that because they don’t survive cold temperatures and won’t grow.
8. A caller has a blue spruce tree that is losing the needles on the east, southeast side of the tree. This area that is dying is not on the shady side of the tree. The trees are about 20 years old.
A. This caller sent photos to me after the show. After further discussion, it was determined that the tree could possibly have a few issues that are common on blue spruces. I assume they may have had some spidermites last summer that killed off a lot of the needles as well as needle cast disease. The spidermites can be sprayed off with a strong spray of water that will knock them off and kill them. There are miticides labeled for use on spidermites, but sometimes using pesticides can kill the predatory insects as well for spidermites causing more of an outbreak. The needle cast disease can be treated by spraying chlorothalonil or copper fungicide on the trees. Fungicide applications should be made in May when the new needles are 1/2 to 2 inches in length and every 3-4 weeks as rains continue. For more information on needle cast, view this publication from the Nebraska Forest Service.
9. Should marigolds be planted into containers or directly into the ground for best growth?
A. Either will work just fine. Marigolds will make a good container garden plant or they can be used among your perennials and other annuals in gardens in the ground.
10. This caller wants to know how to keep grass out of the asparagus? When should preen be used if that is an option?
A. Preen will work well on asparagus. Make sure you use the preen that is labeled for use in asparagus. It can be applied anytime in the early spring on established plants. When dealing with newly planted asparagus it would be best to wait until the asparagus has begun emerging from the ground. Mulch will also help with weed management in asparagus. Grass clippings, straw, or wood chip mulch can be used on asparagus. If applied early enough, the mulch can be a very effective weed control.
11. Can preen be used on flower beds?
A. Preen would be fine in flower beds, as long as the flowers in the garden are listed on the label of that Preen product. However, if any of the flowers are annuals coming up from seed or perennials that are allowed to grow through seed dispersal in that garden, the preen will stop the germination of those coming up from seed. Do not use it in areas where you plan to grow via seed.
12. A listener wondered about relocating lilacs. Can it be done, if so when?
A. Yes, they can be transplanted. The fall would be the best time for this.
13. The last caller of the day has some hickory and pecan trees to plant. Can they be planted around a black walnut tree?
A. Yes, hickory and pecan trees are in the same family as black walnut and therefore are not negatively affected by the juglone that the black walnut produces to reduce weeds around it.
He also wondered if a pawpaw tree can be planted around other trees?
A. Yes, pawpaw is best grown as an understory tree with partial shade.