Answer: Rose-of-Sharon, or Shrub Althaea, can grow to 12' tall. It blooms best if pruned annually (in winter), cutting the previous season's growth back to 2 buds. If you prune more, you'll have fewer blooms. Pruning now (early March) should still provide your plant with ample time to develop new flowering shoots. Don't delay too much longer, however, or the plant may not bloom at all this year.
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