Or I mix some in with my periodic fungicide spray for a foliar feeding. The greenhouse requires more vigilance in watching for pests, but it s also easier to control since it is a confined space. Pests seem to materialize, but their natural enemies don t. The major insect pests include whitefly, spider mites, and sometimes aphids. There are many natural, chemical and growing practice controls for these issues.
Monitoring is key to spotting problems before they get out of hand.
If you spot a disease or insect pest, review the growing conditions. Poor air circulation will guarantee a breakout of powdery mildew. Hot and dry conditions are irresistible to spider mites. For the winter, I usually buy one or two handspray bottles of pyrethrum insect killer for bug emergencies. Both products are synthetics based on natural insecticides and very safe.