What to do with a 15-year old Rose of Sharon shrub (12' tall) that has decided to SPREAD? In the last year or two, my Althea branches, which used to be in an upright vase shape, have dropped and spread out becoming more bowl shaped! What can I do to save these gorgeous bushes?
Rose of Sharon Shrub
Certified GKH Gardening Expert
Has the lighting in the area changed? As in, did the area use to be in full sun and now it is in part sun or part shade? It sounds like the branches are getting leggy trying to reach out for more sunlight, which makes them weaker and floppy.
If the light is the case, you will want to see if there is something you can do to increase light to the area, perhaps by thinning surrounding trees.
You can also try pruning, if you feel it is not a light issue. The branches may just be getting too long and heavy as the grow out, so if you lightly prune the edges of the plant, that will cut the growing tip off of the branches so that the shrub will grow along the branch rather than at the end of the branch.
It sounds like she needs some serious thinning and shaping pruning and this can be done in early spring, such as now, and she will grow back nicely. Here is an article link for you on this subject: https://www.gardeningknowhow.com/ornamental/shrubs/rose-of-sharon/pruning-rose-of-sharon.htm and here is another link to good information: https://extension.psu.edu/plants/green-industry/news/2012/hacking-whacking-dealing-with-overgrown-shrubs