Why isn’t my Rose of Sharon blooming? - Ask Extension
I have a beautiful Rose of,Sharon and looks like something is eating it or a disease. It had buds, then they were gone….
Knowledgebase
Why isn’t my Rose of Sharon blooming? #850039
Asked September 15, 2023, 12:58 PM EDT
I have a beautiful Rose of,Sharon and looks like something is eating it or a disease. It had buds, then they were gone….
Wayne County Michigan
Expert Response
Hello,
This appears to have an enviromental cause, probably the excessive rain we have had since mid-summer. When the blossoms get wet and stay wet for extended periods, they can rot and drop off the shrub. If the shrub is not in full sun this problem can be compounded. Bud drop can also be caused by too much fertilizer, and sometimes it is a combination of issues. The following article discusses bud drop in rose-of-sharon. https://www.purdue.edu/hla/sites/yardandgarden/rose-of-sharon/
I hope this is helpful.
Thank you for contacting Ask Extension.
Ruth
This appears to have an enviromental cause, probably the excessive rain we have had since mid-summer. When the blossoms get wet and stay wet for extended periods, they can rot and drop off the shrub. If the shrub is not in full sun this problem can be compounded. Bud drop can also be caused by too much fertilizer, and sometimes it is a combination of issues. The following article discusses bud drop in rose-of-sharon. https://www.purdue.edu/hla/sites/yardandgarden/rose-of-sharon/
I hope this is helpful.
Thank you for contacting Ask Extension.
Ruth
All the rose of Sharon’s are blooming all around me, except mine. Even neighbors are thriving. I don’t fertilize and the buds have not dropped if….just gone.
Thank you, Bette, for your question!
The literature suggests reasons for bloom or bud drop on your Rose of Sharon shrub. Solutions implemented now may result in blooming next year.
Reasons for no buds forming:
Lack of adequate sun.
Drought during an exceptionally dry summer.
Rot caused because of soil not draining.
Inadequate phosphorus.
Inappropriate or inadequate pruning.
Most of these can be addressed rather easily, although making these corrections will not get you flowers until next season.
Rose of Sharon blooms on current season's growth. The ideal time to prune is late winter/early spring before it produces new growth and blooms on this new growth. I would go ahead and prune at this time removing any branches that appear a "little off", including those with leaves that look somewhat mottled or misshapen. Remove older
and inner branches, dead, damaged or weak branches and those going in the wrong direction. This will restore the shrub's appearance and maximize air circulation in the event of any disease present.
Using a rain gauge, measure the water each week - Rose of Sharon should get about one to one and a half inches of water each week. Too much water can cause root rot and prevent flowering.
Lastly, inadequate phosphorus can be corrected with using a high phosphorus, low nitrogen fertilizer or bone meal. Use sparingly if a soil test has not been performed in the last 3 years.
I also saw a Japanese beetle trap close by your shrub. Consider moving this to another area as these will attract 75% of the neighborhood's beetles leaving the remaining 25% to feast on your plants. This article explains Don’t fall into the Japanese beetle trapping trap | UMN Extension
The article that Ruth Marcy cited in her answer also had some great insight.
Rose-of-Sharon - Indiana Yard and Garden - Purdue Consumer HorticulturePurdue University Indiana Yard and Garden – Purdue Consumer Horticulture
There is a final suggestion. Send your pictures in an email to <personal data hidden> and they will answer without a charge.
If you want specifics to your shrub, they will need sample and for a fee will identify what might be going on. Their website is here:
Plant & Pest Diagnostics (msu.edu)
Again thank you for your question!
The literature suggests reasons for bloom or bud drop on your Rose of Sharon shrub. Solutions implemented now may result in blooming next year.
Reasons for no buds forming:
Lack of adequate sun.
Drought during an exceptionally dry summer.
Rot caused because of soil not draining.
Inadequate phosphorus.
Inappropriate or inadequate pruning.
Most of these can be addressed rather easily, although making these corrections will not get you flowers until next season.
Rose of Sharon blooms on current season's growth. The ideal time to prune is late winter/early spring before it produces new growth and blooms on this new growth. I would go ahead and prune at this time removing any branches that appear a "little off", including those with leaves that look somewhat mottled or misshapen. Remove older
and inner branches, dead, damaged or weak branches and those going in the wrong direction. This will restore the shrub's appearance and maximize air circulation in the event of any disease present.
Using a rain gauge, measure the water each week - Rose of Sharon should get about one to one and a half inches of water each week. Too much water can cause root rot and prevent flowering.
Lastly, inadequate phosphorus can be corrected with using a high phosphorus, low nitrogen fertilizer or bone meal. Use sparingly if a soil test has not been performed in the last 3 years.
I also saw a Japanese beetle trap close by your shrub. Consider moving this to another area as these will attract 75% of the neighborhood's beetles leaving the remaining 25% to feast on your plants. This article explains Don’t fall into the Japanese beetle trapping trap | UMN Extension
The article that Ruth Marcy cited in her answer also had some great insight.
Rose-of-Sharon - Indiana Yard and Garden - Purdue Consumer HorticulturePurdue University Indiana Yard and Garden – Purdue Consumer Horticulture
There is a final suggestion. Send your pictures in an email to <personal data hidden> and they will answer without a charge.
If you want specifics to your shrub, they will need sample and for a fee will identify what might be going on. Their website is here:
Plant & Pest Diagnostics (msu.edu)
Again thank you for your question!
