Posted by Brent Wilson on 8/14/2017 to FAQ (Frequently Asked Questions)
If you've recently planted a shrub or tree that had lots of flower buds on it at planting time, but weeks or months later some or all of the buds are dropping from the plant, there could be several causes.
I wrote this article in response to a customer question about a Rose of Sharon/Hibsicus that flowered some after planting but then started dropping some unopened buds.
There are many possible causes for bud drop. Here are the most common causes:
If the foliage of the plant otherwise looks healthy, it could just be that the plant is using its available energy to produce roots rather than flowers and is therefore dropping some buds. This is common with newly planted flowering shrubs and trees.
Extreme temperature change could stress plants and cause buds to drop. As long as the plant looks healthy it should be fine. If leaves are wilting during extreme heat this might or might not be an indicator of dry soil and the need for supplemental irrigation. More about that in the next paragraph.
Soil that is too wet or too dry can cause buds to drop from plants. Plants might drop flower buds if there is too much water in the soil and roots are suffocated, or if the soil too dry.
Note: It's a good idea to know the specific moisture needs of the plant you are caring for. You can find soil moisture preferences under the Description tab on every plant page in WilsonBrosGardens.com. Additionally, you can find links to helpful planting and care articles provided by our experts under the Planting & Care Advice tab.
Once you know the soil moisture preferences, during the first few weeks after planting you can test soil moisture frequently in order to determine whether irrigation adjustments are necessary, and to get a good idea how often plants will need water in the absence of rainfall. Test soil to a depth of two or more inches with your finger or with a moisture meter. If soggy reduce irrigation. If dry, deeply soak the root ball and surrounding soil. Keep in mind that it's better to deep soak less frequently than to splash a little water around plants every day. Also, make sure to water the top of the root ball as well as the surrounding soil.
Note: If the plant prefers a moist but well-drained soil but the soil in the planting area stays constantly soggy or wet regardless of irrigation and rainfall it might be necessary to test and soil drainage and improve drainage if necessary.
To test soil drainage in a planting area, dig a hole 12" wide by 12" deep in the planting area. Fill the hole with water and let it drain. Then, after it drains, fill it with water again, but this time clock how long it takes to drain. In well-drained soil the water level will go down at a rate of about 1 inch an hour. A faster rate, such as in loose, sandy soil, signals potentially dry site conditions. A slower rate indicates poor draining soil and is a caution you might need to improve drainage, plant or replant in a raised mound or bed, or look for plants that are more tolerant of wet or boggy conditions.
Depending on the sunlight needs of a specific plant, too much or too little sunlight can cause flower buds to drop from a plant.
Note: It's a good idea to know the specific sunlight needs of the plant you are caring for. You can find sunlight preferences under the Description tab on every plant page in WilsonBrosGardens.com. Additionally, you can find links to helpful planting and care articles provided by our experts under the Planting & Care Advice tab.
In closing, if the plant you have is dropping buds but otherwise appears healthy, and you are caring for it properly as advised above, I wouldn't bee too concerned. The plant should continue to grow and establish itself during the current growing season and by next year produce only the number of buds and flowers it can support.
Hope this information was helpful. If you need more details or have any other questions don't hesitate to contact Wilson Bros Gardens. We're at your service!
Plant Long & Prosper!