Answer: With hardy hibiscus or Hibiscus syriacus, deadheading doesn't seem to encourage additional bloom so unless you really want to remove the old spent flowers, it isn't necessary. When the shrub reaches a good size it won't be practical to try to deadhead it, but you certainly may if you want. I have found that it blooms best when the weather stays on the cooler side and the soil is evenly moist (but not sopping wet or saturated, it should just be damp like a wrung out sponge.) Some people find the seedheads ornamental and leave them in place for the winter. The overall shrub can be trimmed back in late fall if you prefer, this will remove the seedheads and also prevent the plant from seeding itself.
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