Experts and BHG readers answer.
holes in geranium leaves
Thanks for writing. Did they have buds when you sprayed them? Some insecticides can cause damage to geranium flower buds.
Other reasons why your flowers may not be opening could include the plants being stressed from too wet or too dry, if temperatures are unseasonably cool or have suddenly become very hot or if your plants have received a dose of too much fertilizer.
---Justin, Senior Garden Editor, BHG.com