I have a ZZ plant which I grow from a leaf and after about 3 years, it is about 8" high and has only 2 stalks. I have only fertilise it once and water it sparely every week. How do I get it to grow bigger and more stalks?
Fertilize with half-strength every time you water - and post us a picture. Maybe there's something going on with it, and seeing it will help us help you.
There are numerous sub species within the species Zamioculcas zamiifolia. Some grow tall, others are quite short. This is a natural thing so it may be you simply have one of the smaller subspecies. However, the plant does very well with more water, far better than most websites wish you to believe for unknown reasons. Follow lorax' advice and increase the frequency of the water. Try at least once a week, however I have exchanged information with the directors of botanical gardens in the United States who water them even more frequently (daily) with no ill effects. It is very important the plant be in fast draining soil which is sandy. Cactus soil is a good choice. They don't like wet roots. Some years ago all the subspecies within the species Zamioculcas zamiifolia (ZZ) were combined into a single species. You might find this thread of interest: http://www.botanicalgarden.ubc.ca/forums/showthread.php?t=29376&highlight=Zamioculcas+zamiifolia
