most general insecticides available at the big box stores will take care of whiteflies... take them out of the greenhouse and spray them very well.. be sure to get under the leaves so that you reach all the whitefly larva or they will come back... wait 2-3 days and spray again.. depending on the conditions in your greenhouse you may have to spray the greenhouse itself once so they don't migrate back to the plants as soon as you put the plants back in there

It's very important that you use pesticides with great care in an enclosed environment such as a greenhouse. Perhaps especially so with one that is attached to your home. Many cannot and should not be used under such conditions.

Much safer alternatives include sticky traps, horticultural oil and neem.

you try and control whiteflies with hort oil or strips they will just laugh at you... its a small tilt type greenhouse... kill the whiteflies with insecticide and then if you are super concerned about it rinse it out with water

Insecticidal soap sprays every couple of days should do it. There isn't much you can do about the ones that are already flying around, but if you spray the plants with soap every few days, you should be able to smother the larva that can't fly, thus preventing anymore egg-laying flyers. That's how it's supposed to work, anyway : )

Renee