We have many (80-100) young seedling plants from our Rose of Sharon. At what point can I transplant them? They are about 6 inches in height and this is their second summer. We also have a Rose of Sharon about 4 years old that is healthy but will not produce flowers. Can you advise us on both issues?
You can transplant this fall. Remember to water well. As for your non-bloomer, it might be a lack of sun or too much nitrogen.
How and when can I cut the stems of my Rose of Sharon to grow more plants?
I would say yes. Since Rose of Sharon shrubs are actually a variety of hardy hibiscus, cutting would be taken much the same way. They also self-seed when not deadheaded, so you just might find some seedling growing beneath the shrub, which you can easily pull and pot up or transplant elsewhere. These articles will help: https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-propagation.htm
How do I propagate my Rose-of Sharon?
Rose of Sharon is a variety of hardy hibiscus, and can be easily propagated through cuttings. This article should help: https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-propagation.htm
In addition, the plant self-seeds readily when blooms have not been cut, so you may find young seedling growing beneath the shrub as well. These can be lifted and grown in a container or transplanted elsewhere.
Shrubs include Mountain Laurel, Hydrangea, and Rose of Sharon.
These articles will help you with hydrangea and rose of sharon:
The mountain laurel should be pruned in late spring.
I would like to know how to protect the rose of Sharon from the winter weather.
Rose of Sharon need no additional care for winter. If they are new plantings, you can mulch around their base to ensure that they are fully established.
When is the best time to prune these bushes?
This article will help with that: https://www.gardeningknowhow.com/ornamental/shrubs/rose-of-sharon/pruning-rose-of-sharon.htm
Purchased 3 rose of sharon hibiscus plants and planted them outside. How should they be cared for over the winter?
Rose of Sharon is a hardy plant and should be fine with no extra care. But since they are new plantings, if you want to mulch around the base of the plant for added protection, that will not hurt them and will help protect them if they have not fully established yet.