Rose of Sharon has Rose too High

I have a "Rose of Sharon" that is about 20 years old and that now consists of five or six trunks (with their branches of course). Each trunk is about 18' tall and about 4" diameter at a height of about 5' and perhaps 3" at a height of 10'.

It has never been pruned, as the dimensions might indicate, although I have cut down three trunks over the years for one reason or the other. But I intend to prune it fairly soon.

From what I read, I should cut off the top 6' or so. Easy to understand... although perhaps not easy to do without a helicopter... but I am sort of troubled about leaving virtual stumps. Yet I see no alternative. Does anyone have any comments?

 

I'm not going to answer this, but maybe it would help to see photos.

 

Wait until early spring and then cut down to low stumps - these shrubs bloom on new growth, can be pruned low every year once well established. And have comparatively little appeal as the tall, leggy and often leaning specimens they make if left unpruned for extended periods.

 

Needs some photos for identification - the name 'Rose of Sharon' has been applied / misapplied to multiple species. To me, it means Hypericum calycinum.

 

Nobody in Vancouver talking about a 10 ft. high shrub called rose of Sharon is going to be referring to Hypericum calycinum. Or any other plant that does not grow 10 ft. tall and does not get called rose of Sharon on a routine basis in North America.

 

The Rose of Sharon in question would be Hibiscus syriacus. Tall shrub, flowers in late summer, beloved of pollinators. Tough as nails!

 

Photo shows hibiscus syriacus 'Red Heart', one of the most common varieties. Not sure if this is the variety you have but regardless of variety they are all "tough as nails".

They should be pruned regularly to keep them under control but as you said, the one in question hasn't been. I prune mine yearly so have not had to handle a large one but my neighbour cuts his back to a stump of less than 1 meter every 3-4 years. This leaves an ugly mess of stumps but by the end of summer new growth has appeared and by the next summer all you see is a bushy mass of flowers. He only allows it to reach a height of about 2.5 meters over that 3-4 year period.
In your situation I'd get a sturdy ladder (with spotter) and an extendable electric pole pruner and take off what you can. It may take awhile to bring it down to a height that you want and you may have to look at "ugly" for a while but once brought under control it will be much easier to keep it under control.