Unless you live in NY, CT, MD, MA, ME, or VT. I'm surprised its still for sale in California.
imidacloprid is a systemic, that means the poison is absorbed by the roots, stems and leaves of plants - it will kill everything with impunity, including bees, butterflies and you if you use it on a food crop. If you buy it, use it inside only, never on outdoor plants.
Gnats are an indication you are a consistent overwaterer. Use the mosquito bits, Insecticidal Soap as a drench or allow the soil to dry between waterings, much better choices then allowing something like imidacloprid loose in the environment.
