Yard and Garden: June 12, 2015

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This is the Q&A for the Yard and Garden show for June 12, 2015. 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, 2015. 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, Extension Educator in Dodge County

1. This caller has asparagus that is going to seed and is growing very large, does it need to be left up and growing all year?

A: It is best to allow the plants to grow all summer. This will allow it to build up nutrients to be used next spring to get the plant growing early in the season. It can be cut back to the ground late in the fall.

2. A caller had rabbits that eat his tomato plants off at the ground level. Will these plants grow back or should he replant?

A: This late in the season it would be best to replant the tomato plants. It is also advised that a rabbit fence is put up around the garden. To keep rabbits out of a garden, the fence needs to be at least 2 feet tall.

3. A lady has Black-eyed Susan’s growing in her garden for a couple of years now and they have gotten black spots on the leaves of the plants. She put sevin on it and the plant still has black spots on it.

A: This would be a fungal leaf spot disease that is common on many asters including Black-eyed Susan. Sevin is an insecticide that would only be affective on insects and not on fungi. Cleaning up the garden in the fall and removing infected leaves throughout the growing season will help reduce the spread of this disease. Also, ensure that when watering is necessary, it is applied to the base of the plant rather than over the top of the leaves. This is not a disease that typically needs to be treated for as it causes only minimal damage to the plant.

4. A woman who is moving from her home would like to know if it will be alright for her to transplant her iris and lilies to her new home at this time of the year?

A: The best time to transplant these would be in the fall, but if necessary, they can be transplanted now. Just take time to give these plants extra care and ensure that they are getting sufficient water throughout the season as they will not have a well-developed root system to deal with the hot and dry conditions we typically see in the summer months.

5. When is the best time to transplant peonies and how deep of a root system needs to be taken with the plants?

A: Fall is the best time to transplant peonies. When transplanting any plant take as much of the rootball as is possible and backfill with the same soil that was removed from the new location when the hole is dug. For peonies, pay close attention to where they are planted currently and make sure that they are not planted any deeper in their new location or they will not bloom again until they are lifted to higher in the soil profile.

6. A caller’s husband sprayed her garden area with Roundup. When can she safely plant this into a vegetable garden?

A: It will be fine to replant. As long as you wait 3 days to replant after roundup, or any glyphosate product, it will not harm the crops you plant on it.

7. A gentleman is growing purple onions and now they have started to produce seedheads. What should be done about this, is it a concern?

A: Cut off the seedheads or they will take too much energy to put into the seedheads and not enough into the onion.

8. A gentleman has a tree that is suckering. Can he spray anything on those to stop the growth of so many?

A: No, these suckers are coming up from the roots of the main tree. Anything sprayed on the suckers will translocate into the entire tree. The best control for suckers on a tree is to continually prune them off throughout the growing season.

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9. A caller has a spirea that is 3-4 feet tall. Is this as large as they should get? When should they be pruned for maximum growth?

A: Spireas typically grow to 3-4 feet, so this is probably about full grown size. Some varieties will grow larger and some will grow smaller, it depends on the variety, but most commonly they are found in the 3-4 foot range. If it is a summer blooming spirea prune it in the late winter or early spring just before growth begins. If it is a variety of spirea that blooms in the spring, prune it in the late spring, just after it has finished blooming for the year.

10. A caller has tomato plants that were planted in a location 75 feet away from where they are typically planted because they always see leaf curling and they are still curling up in the new location. What is causing this and how can it be remedied?

A: This could be a herbicide drift issue which will cause cupping, curling, and distortion of the leaves and stems. It could also be a physiological leaf roll issue that is common this year due to the wet, cooler weather. The plant will grow out of either of these issues to not be problematic to the plants later in the growing season.

11. A lady was wondering when hibiscus can be transplanted?

A: It can be transplanted either now or in the fall when you can see the plant because it is late to emerge in the spring.

12. A caller has broccoli growing in his garden that now has developed holes in the leaves. Will sevin or eight work for this problem?

A: Yes, this is probably due to cabbage looper which can be controlled with a general insecticide such as sevin or eight.

13. A gentleman has tomatoes that have curled up leaves that look like they have been sprayed. Is it a spray drift issue?

A: Tomatoes are very sensitive to spray drift so it could be that. It could also be physiological leaf curl. Both of these problems will work their way out of the plants.

14. The last caller of the day has potatoes that are turning yellow and wilting over. What is causing that?

A: This is probably due to too much moisture. Check the potatoes for rot.

Weather Effects on our Plants

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This year has been a bit unsteady regarding growing conditions for many plants. I have been getting a lot of questions regarding the death in many plants this spring and the lack of growth in many of our plants as well. I wanted to take this time to go over this issue with all of you.

This spring we have been seeing quite a bit of dieback on many different perennial plants and shrubs. Roses and spireas are suffering from what we call winterkill. Winterkill occurs commonly in the winter months when plants are exposed to cold, drying winds. The winterkill was extremely hard on these plants this year and has caused the tops of them to die. What we are seeing in our landscapes is plants that only have leaves at the bottom of the plant with no leaves and brittle branches at the top of the plant. Many other shrubs are experiencing the same problem. These dead branches can be pruned out of the plant. If the plant affected was a rose, it could have more problems if the dieback occurred below the graft union that many roses posses. If it died below the graft union, it should be replaced with a new rose.

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We are also seeing a great deal of loss in willow trees. Many willow trees, throughout the state, are dying entirely or losing the top or many branches throughout the tree. This is attributed to many years of tough growing conditions. In 2012 our plants faced severe drought and three weeks of temperatures in the 100’s. This is very hard on our plants and it takes 3-5 years of normal growing conditions for a plant to recover from a drought like this. This drought was followed by the winter of 2013-2014, which was very dry, cold, and windy. That winter caused many of our plants, especially arborvitae, to die due to the desiccation they faced. Finally, we have had a very uneven warm up this spring that followed a quick drop in temperatures last November, when temperatures fell to only 5 degrees Fahrenheit.

It is very hard on plants to go through so drastic extremes during their growing season and to have it hit them for multiple years at a time. This is the reason for so much death and dieback in so many different plants.

A lot of our plants are also very slow to warm up this spring. Butterfly bush, privet, hibiscus, and beauty bush have still not broken dormancy this spring. We at Nebraska Extension are suggesting waiting until the beginning of June before giving up entirely on these plants.

Many of our vegetable plants, if they have already been planted, may not be growing very well at this point. They are slow to grow well in this cool, cloudy weather. They will catch up when it warms up.

Keep an eye on all of your plants for diseases that are sure to be a problem with this weather. Leaf diseases and fruit diseases could be a problem this year as many are common in wet, cloudy weather. Watch leaves for leaf spots to remove those leaves as soon as you begin seeing a spot on them. When you need to water, be sure to water your plants from the bottom rather than overhead to reduce spreading these diseases.