The Q&A Archives: knockout roses

Question: how to I prune these bushes and what is the best treatment to get rid of the japanese beetles that have started to overtake my new bushes.

Answer: You can prune your knockout roses in the spring and then as needed during the summer months. I do a major pruning (by one third) in the spring and then during the growing season I clip back any unruly stems as they appear. Japanese beetles are a difficult pest to control. Your best bet is a two-prong approach: one to deal with the larvae, one to deal with the adults. Japanese beetle grubs are best controlled by spraying beneficial nematodes on the lawn and garden area. These microscopic worm-like creatures attack only the grubs in the soil and not plants, animals or humans. Spray them in spring when the temperatures are above 55F. You can buy the beneficial nematodes from Gardeners Supply, 128 Intervale Rd., Burlington, VT 05401 800-863-1700 For adult beetles, I'd try a new product called whole neem oil. This is different than standard Bioneem in that it is a stronger concentration of this organic spray.

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