If a pot does dry out, you will probably have to set it in a saucer or tray to re-soak up water. Fertilizing container roses in a greenhouse is not complicated. Just don t do as much of it. 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.