Pruning a Rose of Sharon - Knowledgebase Question

Hudson, Ne
Question by jbreard
July 25, 2010
My Rose of Sharon suffered a lot of winter damage last year. It has a lot of lichen growing on it and many branches appear to be dead. Other branches are doing OK and producing buds.It has not bloomed yet although others in our region are in full bloom.
When is the best time of year to prune it and how much do I safely remove? What is causing the lichen to grow and should it be scraped off? TY


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Answer from NGA
July 25, 2010

0

Lichen tends to grow on woody perennial plants, especially if the air circulation is poor or there's a lot of shade. But, even if growing conditions are perfect, it can still form on woody branches. It doesn't really hurt your plant, other than to hold excess moisture against the bark which can cause the bark to rot. You can kill it if you spray your woody plants in the late winter with a lime/sulfur (bordeaux) mixture such as is used on apple and other fruit trees. The lime sulfur will kill the algae and it will slough off in a year or two. Rose of Sharon can be slow to grow and bloom and these plants can be pruned back quite hard. I think I'd start by removing the obviously dead branches and then shortening the others. Rose of Sharon will bloom on the new growth of the season so you may still get some flowers if you prune yours back now. Or, you can wait until early next spring, prune it back hard and if there's still some lichen on the plant, spray it with a lime/sulfur. Best wishes with your Rose of Sharon!

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