From:Austin, TX Region: Southwest Topic: Non-Natives Title: Thinning of non-native rosemary Answered by: Nan Hampton
I live in NW Austin and have a very large rosemary bush that is having problems this season. We trimmed the bush in early March because the plant was getting too large for the space. It is roughly 3 feet deep by 7 feet wide. It has small purple flowers that bloom on it in the early spring, so I'm not sure which variety we have. The bottom of the plant is basically 10-12 inches of sticks. The new growth is coming in at the top of the plant, but underneath looks really terrible. I assume, eventually, the top growth will cover the ugly parts below, but I'd like to have a healthy plant again. Any suggestions? (I did notice a spider web in the base of the plant yesterday, what pesticide would be best to use?)
Rosemary (Rosmarinus officinalis) is an introduced species from the Mediterranean region that has been used extensively over the South for landscaping. Since the Wildflower Center's focus and expertise is in plants native to North America, rosemary isn't really in our purview. We can tell you, however, that it sounds as if your plant needs to be thinned considerably to regain its health. Many plants will not produce new growth from old, hard wood at all, some only form the end of pruned wood. It sounds like that is what is happening with your plant. You can read more about its care from The Backyard Gardener.
Concerning the spider web in your plant, spiders in general are good news for gardeners since they trap and eat insects that may be injurious to your plants. Mr. Smarty Plants doesn't see a need for a pesticide to kill spiders.
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