Zonal geraniums tend to grow upright, growing to about 18 inches in one season with large, 4- to 6-inch double flower heads.
Transfer into pots that are at least one and a half to two times the diameter of the pot you purchased the plant in. Use well-drained soil, and avoid field or garden soils. The ideal soil for zonal geraniums contains mostly coarse peat moss mixed with vermiculite and perlite.
To ensure the overall health, attractiveness and growth of zonal geraniums, you must remove all old flowers and leaves regularly. The entire flower stem should be removed where it meets the main stem to avoid fungal diseases, but take care to avoid damaging the main stem when doing so.