Why Are the Flower Buds on My Rose of Sharon Not Opening?

The Reasons for the Problem, and How to Solve It

Image of pink rose of Sharon flower with deep pink throat and prominent stamen.
Rose of Sharon's flower is adored by millions, thanks to its bi-coloration and showy stamen. David Beaulieu

Are the flower buds on your rose of Sharon not opening? Do not panic. This is a common problem, and there is likely a simple explanation for it (even though it may be too late for you to correct the problem for this year's blooming season).

The blooms of rose of Sharon (botanical name, Hibiscus syriacus; alternate common name, "shrub althea") are most welcome, coming as they do in the latter half of the summer -- when most flowering shrubs have finished flowering.

But, occasionally, I receive emails such as this one from Theresa J., asking why a rose of Sharon's flower buds are not opening:

"What can you recommend for a rose of Sharon bush that has many, many buds but will not flower? The shrub is three years old and has never had trouble blooming in past Augusts. What could I be doing wrong?"

Possible Reasons Why Your Rose of Sharon Is Not Blooming

There are many possible answers as to why your rose of Sharon flower buds are not opening, including:

  1. Excessive shade: Rose of Sharon will not bloom up to its full capabilities if given too much shade.
  2. Rot: During rainy summers, rot can set in and ruin the flower buds (although you may not notice it from the outside). The same effect can be produced by excessive watering if you water overhead.
  3. Drought: Conversely, during dry summers, rose of Sharon flower buds may be damaged from drought and fail to open.

    How You Can Solve These Problems

    Problem #1 is easy to solve, especially if you are able to exercise some forethought. This is a plant for full sun. When you are planting the shrub, make sure that you are giving it a location that receives at least six hours of direct sunlight per day. If you have planted it in an area that is too shady, consider transplanting the shrub to a more suitable location.

    Regarding problem #2, be sure to direct the spray of your garden hose to the soil around your rose of Sharon when watering. If you spray high, you will be drenching the flower buds, which invites rot. Of course, the rain will soak the flower beds, and you have no control over that. Nonetheless, if your shrub is properly located (that is, in full sun), the sunlight will help dry the water off the buds after a rainfall.

    Problem #3 is the easiest one to solve.  Simple keep your plant adequately watered during the summertime. Make an extra effort during periods of drought. How much water should you give your rose of Sharon? The exact amount (and the precise frequency of watering) will depend on the conditions. For this reason, rather than trying to put a number on it, just remember this: the soil around your plant should be kept evenly moist. Gently dig six inches down into the soil and feel it. The soil should feel neither dry nor soaked, but rather slightly moist.