The cherimoya is subtropical and when full-grown can survive to 25F. Young trees are susceptible to frost. Trees do not like intense heat or desert conditions. 50-100 hours of winter temperatures between 32-55F is usually necessary for fruit production. Cherimoya's prefer a summer temperature of 65-80F, and a winter temperature of 41-65F. Trees are fast-growing, producing fruit from seed in 3-4 years. In cool climates, branches will defoliate for a few months in winter. Flowers are formed in small groups at nodes along the branches. A single flower first opens as female, which lasts for 36 hours, followed by a male stage, lasting for another 36 hours. Flowers are almost never pollinated by their own pollen, and without proper pollinators which do not exist outside its native range, cherimoya's must be hand pollinated. Pollen is generally collected from a few male flowers and stored in a small bag while it is used to pollinate female flowers. Pollen cannot be stored for more than a few hours before it loses viability. Flowers bloom from late winter to early summer, followed by fruit which ripen from October to May. Fruits are large, from 4-8" long, and sometimes weighing over 5 pounds. Harvest fruits when skin turns slightly yellow or pale green, or when skin gives a little to touch. Cherimoya's like cool summers and cool nights. Very hot or cold weather, and cold or hot winds can be damaging. Water frequently when the plant is putting out new growth, infrequently when the plant is dormant. Fertilize every three months for best growth. Propagation: Propagation is by seed, grafting, and air layering. Grafting and air-layering are chosen to propagate select cultivars. Seedlings with 70F bottom heat germinate in about 21 days. Without heat, seeds may take 1-2 months for germination