One of our readers, Kim, posed the question:

I have two very large, potted [Hibiscus], outside in the summer, inside in the foul weather of winter. They are getting a little “stringy”, I know they need pruning, but not sure how far down to go….please help!

Hibiscus syriacus (Rose of Sharon) is what we have in the Northwest.  It is a deciduous shrub that buds out late in the season causing most people to think that their plant has died over the winter.  My assumption is that this is not the variety you have.  Odds are you are the owner of Hibiscus rosa-sinensis (Chinese Hibiscus).  This is what we would call a “patio-tropic.”  A lovely plant that looks pretty in the summer, we take it inside in the winter and it promptly dies.  Therefore, I actually had to consult a book for help with this one.

According to my research these plants can sprawl over time.  The first rule of pruning is “Dead, dying or diseased.”  Prune those out first.  To rejuvenate the plant remove all the older branches and cut the remainder back hard.  Yes, it will look ugly at first.  9 times out of 10 the plant will come back and bush out.  On occasion the plant can’t handle the stress of the excessive pruning and will need to be replaced.  Pruning should be done in the spring.

This is true about many plants in the Malvaceae family.  I have a Tree Mallow (Lavatera thuringiaca) in my garden and it sprawls like crazy.  I prune it back to the ground in the spring.

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In bloom this week:

Primroses, early crocus, Witch Hazel (Hamamelis x intermedia), Heath (Erica carnea)