Can Rose of Sharon be grown in tree form?

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Q. I am fond of the shrub commonly known as Rose of Sharon, which I believe is a hardy hibiscus. I’ve only ever seen the plants grown as shrubs that bear beautiful, tropical looking flowers all summer. Recently a friend living near London (England) sent me a photo of a plant with the same flowers, but it was growing as a street tree planted by the local municipality. Can you explain? It looked like Rose of Sharon, but it was definitely a tree.

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A. Rose of Sharon (Hibiscus syuriacus) is grown almost exclusively here as a deciduous shrub, around three metres tall, with showy, hollyhock-like summer and early autumn flowers. The plant’s naturally vigorous growth and vase-like shape makes it easily grown as a multi-stemmed shrub; however, that growth can also be thinned to create a small, single-stemmed tree.

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Nurseries I’ve spoken with indicate they haven’t seen this hibiscus available in standard (tree) form and, if it were available, they might not be inclined to order it in because the plants are difficult to keep looking good in nursery pots.

If you are really keen to try for a tree form Rose of Sharon, look for the youngest plant you can find in the spring, a small shrub with one obviously predominant, straight stem, and eliminate the other stems to create a tree. As the small tree develops, keep pruning away secondary stems as they arise.

Q. Fruit fly season has begun, just as I’m processing garden fruit. What trapping method works for you?

A. I use apple cider vinegar, around three cm deep only, with a drop or two of dish soap, in a shallow glass jar.

Or, use just the vinegar and secure plastic wrap over top. A few holes poked in the plastic wrap allows the flies to enter, but they won’t be able to find their way out. Using a glass jar allows you to see the trap is working to attract flies.