Before dividing and repotting succulents, mix together equal amounts of perlite and sand with half as much manure, then combine them with an equal amount of potting soil.
Next, separate an overgrown pot of flamingo-head gasteria (Gasteria x hybrida). When succulents become overgrown in their pots, water flows over and off the roots rather than being absorbed into the plant (Image 1). Using a sharp knife, open up the rootball and remove young shoots. Due to the high water content of succulents, to prevent rot possibly developing at the site of the cut, new shoots and their roots should be left exposed to air for as long as four days to harden off the break points (Images 2 and 3).
Add fresh soil to a clean pot, making several deep depressions in the soil and placing a new shoot in each of the depressions. After pressing the soil in place around the shoots, add approximately 1/2" of fine gravel to the top of the soil; the weight of the gravel will help hold the shoots upright, keep the soil in place during watering and ensure quick water drainage away from the plant at the point where the plant meets the soil line, the site at which most plant rot begins.
Whiteflies can be a problem in greenhouses, especially on plants like pink flowering maple (Abutilon hybridum 'Roseus'). Commercially prepared chemicals, sprayed over the tops and up underneath the leaves, can coat the leaves and kill whiteflies. Before applying pest control, remove the plant from the greenhouse and let the foliage dry before returning it to the greenhouse.