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Ron Smith answers questions about flowers, trees, gardens and shrubs.

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I have a white peony plant that looks healthy and produces loads of blooms. The blooms open to very large flowers. Unfortunately, all the flowers have a brown edging on each petal. Except for the brown edges, the flowers look healthy. This has been going on for about four years. Should I get rid of this plant? I have a Sarah Bernhardt peony planted next to the white peony that is doing fine. (email reference)

A: This is sometimes an indication of the plant being planted too deeply. To get planting and cultural tips on peony care, go to

Q: Can I root a croton in water? (email reference)

A: It is not a good idea. Crotons should be rooted in a pasteurized media that you can purchase from a garden center. Generally, roots that develop in water are not stable. The new plant will have a difficult time establishing itself when moved into a container with soil.

Q: I have two prairie roses in the backyard that have survived mowing, building and dirt piles. I want to replant them to a flower bed where they deserve to be after all these years. How do I transplant the roses? I won’t even categorize myself as a novice at gardening because I’m more of a dabbler. Your assistance will be appreciated. (Bismarck, N.D.)

A: Hearing what these plants have gone through, I’d say your chances are right up there for success. You sound adventuresome, so give it a shot. Cut the bushes back to a manageable size. Dig the holes where you want to move the plants. Dig out the plants in the cool of an evening when rain is in the forecast. Take as much of the root ball as you can handle. Place the rose bushes at the same depth into the new holes and water well. Monitor and water as needed during the next two to three weeks. By then, the roots should be established and can pretty much fend for themselves for water and nutrients unless an extended drought and high temperatures show up. Give them a shot of Miracle-Gro at transplanting, 30 days later and around the Labor Day weekend.

Q: I planted two flowering dogwoods in my front yard. I planted azalea bushes and perennial flowers around the base. The trees have been in the ground for nearly two years. One tree is flourishing with lots of leaf development and a few blooms in the spring. The tree also is getting taller. The second dogwood appears to be in some distress. We were hit with a hurricane last fall, so the tree was whipped back and forth by the wind. It wound up bent over at a 45-degree angle to the ground. Before winter, I secured it in place with stakes and lines and was careful not to damage the branches and trunk with rope. It stayed upright all winter but has not put out any leaves this spring. The round buds are there, but they never opened into leaves. The trunk and branches seem to be in good shape. I took a small branch end that was not much thicker than a toothpick and broke it to see if it was dead. It didn't break clean like a dead piece of wood does. This made me think that the tree may recover. Should I give it a lot of water because we have had a dry spring? I have treated it with a Miracle-Gro solution. I am interested in hearing your thoughts, and thank you in advance for any help you may be able to give me. (email reference)

A: Well, I wouldn't bet the farm that the tree will recover. When a tree has gone through a trauma such as you describe, there is a good chance of internal structural damage that could spell doom for the tree. I'd give it until Memorial Day weekend to see what happens. If no leafing out takes place by then, I'd say take it out and replace with a new planting.

Q: I planted four peony bushes that bloomed this year. However, the blooms only lasted a few days. The neighbor next door has a water sprinkler system to water the grass, which also waters the peonies and then the petals fall off. I am not sure if I should try to move them. I also am wondering how much water the peonies can stand and if the sprinkler system will harm them. Should they be watered from the ground? I am new at planting flowers and didn't realize I would have a concern about the water sprinkler system. Thank you for your advice. (email reference)

A: You must live well into the southern part of the U.S. to have your peonies finished with their blooming. It is true that sprinkler systems intended for turf grass growth are not the best thing for peonies, so I would suggest that you ask your neighbor to recalibrate the sprinklers that are impacting your peonies or move your plants this fall. Go to for a publication on peony culture and care. Adjust all the dates to fit your location. Keep in mind that peonies are not known for holding their flowers very long. I view them as a nice herbaceous hedge that produces spring flowers that look nice for a very short period of time and then gets the landscape messy with all the dropped flower petals. However, they are fairly attractive when everything is cleaned up.

Q: My arborvitaes became bare in the middle this winter. I read that deer feeding on the branches could be my problem. The arborvitaes were completely normal last fall. (New Jersey)

A: White-tailed deer are famous for doing just that to arborvitaes. They were almost extinct in New Jersey years ago, but conservation has returned them to full force. This has driven the deer to leave forest-edge environments and wander into residential sites where they find an abundance of very edible shrubs and trees to nibble on. My folks lived in eastern Pennsylvania by the New Jersey border. You’d think the neighbors were raising the deer as pets because they were so bold and friendly. Unfortunately, once they’ve cleared out that part of the tree, it will not regreen to any extent, so the deer have ruined the plantings. In the future, use Liquid Fence or Plantskydd to keep them from getting started on your plantings.

Q: What is the ratio of bleach to water to soak iris rhizomes? (email reference)

A: Usually a 10 percent solution of bleach to water. Soak the rhizomes for 10 to 12 minutes.

Q: Our spruce is growing from side to side with little growth at the top. Is this normal? If not, do you have recommendations for getting more top growth? (New Oxford, Pa.)

A: What you are describing is not normal. Something has killed the apical shoot tip. If you want more vertical growth, you need to find the longest lateral branch at the top and stake it so that it is in a vertical position. This will cause a crook in the tree's shape but will not be noticed as time passes. This answer is based on the assumption that you did not plant one of the dwarf or spreading cultivars.

Q: When I run into a horticultural pickle, you are one of the first I think of to offer a solution. This time, I am asking you to help find a way to treat crown rot on irises. Through my research, I came across Terraclor powder but cannot find where to buy it. Can you suggest how to deal with this new-to-me disease? (email reference)

A: People think of me for the most interesting reasons. Crown rot treatment is difficult, especially if it’s not caught early enough, which often happens. Usually, there’s little you can do to save the plants, so prevention is important. Being a soil-borne fungal disease, it will develop again when conditions are favorable. The infected plants should be removed and destroyed when the disease is discovered. The use of fungicides can help prevent the spread of this disease but usually are ineffective once it’s completely taken hold. Most often used is Captan or Aliette. Drench the soil (2 tablespoons to 1 gallon of water) while somewhat dry to allow the fungicide to penetrate well. Repeat this twice at 30-day intervals. Try to do everything possible to improve drainage, sunlight penetration and air circulation. We had to move our iris plants from one location where this disease was prevalent to a better one. We tossed the rhizomes that were anywhere near the infected plants. For four years, this action has worked without using any fungicides.

To contact Ron Smith for answers to your questions, write to Ron Smith, NDSU Department of Plant Sciences, Dept. 7670, Box 6050, Fargo, ND 58108-6050 or email

NDSU Agriculture Communication – May 30, 2012

Source:Ron Smith, (701) 231-7971,
Editor:Rich Mattern, (701) 231-6136,
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