The climatic requirements of the cherimoya have been indicated in the discussion of the regions in which it is cultivated. It is essentially a subtropical fruit, and in the tropics succeeds only at elevations sufficiently great to temper the heat. It thrives best in regions where the climate is relatively dry. In the southern part of Guatemala, where the annual rainfall is about 50 inches but where there is a long dry season, it is extensively grown and the fruit is of excellent quality; but in the northern part of the same country, where the rainfall is nearly 100 inches, distributed throughout the year, the tree cannot be grown successfully. In the highlands of Mexico it is best suited where the climate is dry, free from extremes both of heat and cold, and where abundant water is available for irrigating. The climate of southern California, except in sections subject to severe frosts, seems almost ideal for it. In many places frost is the limiting factor, for the cherimoya, while the hardiest of its genus, does not endure temperatures lower than 26° or 27° above zero without serious injury. Young plants will, of course, be hurt by mild frosts which mature trees would ignore; in fact, temperatures lower than 29° or 30° are likely to injure them.
Like other annonas, the cherimoya prefers a rich loamy soil. It can be grown, however, on soils of many different types.
In California it has done well on heavy clay (almost adobe), while in Florida it makes satisfactory growth on shallow sandy soils. H. F. Schultz considers the ideal soil to be a fairly rich, loose sandy loam, underlaid with gravel at a depth of two to three feet. He says: "Some of the best Campo Santo and Betania (Argentina) groves are located on such land, which is furthermore characterized by a liberal outcropping of scattered rocks." Carlos Werckle states that the tree does well in Costa Rica on "stony cliffs." He reports that it is more productive under these conditions than when grown on richer soil, and himself considers it partial to mountain slopes on which there is much limestone rock.
Experience in California has shown that the cherimoya requires cultural treatment similar to that given the citrus fruits. Budded trees should be planted in orchard form about 20 to 24 feet apart; seedlings about 30 feet apart, since they grow to larger size. Irrigations, followed by thorough cultivation of the soil, are given at intervals of two weeks to one month. While the trees are young, more frequent irrigations are necessary. In Argentina, according to H. F. Schultz, it is the custom to irrigate the trees at intervals of six to twelve days. In Mexico two weeks is considered the proper interval.
In California, stable manure has been used for young trees with excellent results, and occasionally for bearing groves. Little attention has been devoted to the subject; hence it is not possible to give specific directions for the use of fertilizers. A writer in the Queensland Agricultural Journal recommends that each tree be given annually 1 to 3 pounds of superphosphate, 2 to 6 pounds of meat-works manure with blood, and 1 to 2 pounds of sulfate of potash.
The pruning of cherimoyas has received little attention as yet in the United States. In Argentina it is considered that trees which are kept low and compact are both more precocious and longer lived than those which are tall and open in habit.
In Guatemala the most productive trees are usually those which have been cut back heavily. It is possible that fruitful-ness can be increased by severe pruning. The matter deserves careful investigation. The tree being semi-deciduous, pruning should be done after the leaves have dropped and before the new foliage makes its appearance.