The kaki is distinctly a subtropical fruit and thus is not successful in the moist tropical lowlands, although there are many elevated valleys and plateaux in the tropics where it can be grown. Its culture in the United States is limited to regions which are suitable for the fig. Some varieties have survived temperatures as low as zero, while others are more tender. L. H. Bailey writes: "Many seedlings have been produced which seem to have increased frost-resisting powers. Instances are reported in which some of these trees have withstood the winters of east Tennessee. By successive sowing of seeds from these hardier seedlings we may look for a race of trees which will be adapted to the middle sections of the United States. There is a probability, also, that importations from the north of China and Japan may considerably extend the range northward in this country. Some varieties have succeeded in central Virginia and Kentucky."
Regarding the moisture requirements of the kaki, experience indicates that it does not need a high degree of atmospheric humidity if it is supplied with plenty of water at the root. T. Ikeda says of the trees in Japan: "They are very water-loving in habit and require a constant and sufficient supply of soil water." The behavior of the species in California has shown that it is entirely successful in a semi-arid climate, while experience in other regions indicates that it can be grown equally well in a region of reasonably heavy rainfall. In parts of India where the precipitation is extremely heavy it has not done well.
In soil requirements the kaki is not exacting. Emile Sauvaigo, one of the best French authorities, says: "It likes a deep, reasonably heavy, well-drained soil, and it does well on clays, when they are not too compact"; and Ikeda notes that the yield is larger, and the color and quality of the fruit better, when the trees are planted on heavy but well-drained loams. In California it has been observed that they make larger growth on heavy than on thin sandy soils, which would, of course, be expected. Satisfactory results are obtained in Florida on light sandy loams, particularly when they are moist; in fact, it seems difficult to give the plant too moist a situation, provided the drainage is good.
Florida nurserymen advise that the land on which kakis are to be planted be prepared in advance by growing a crop of cowpeas or velvet-beans and plowing them under to enrich the soil. Planting may be done in the lower South between November 15 and March 1, but preference is given to the period from December 1 to February 1. The trees should be spaced 18 or 20 feet apart (134 or 108 trees to the acre). As much as 24 feet is considered a desirable distance in California. The roots should not be allowed to dry out while the trees are being set. The tops should be cut back to 2 or 2 1/2 feet on plants which have not large stems. Roeding says: "The tap-root should be cut back to 18 inches, and fresh cuts made on all the fibrous roots. After the trees are set, head them back to 18 inches. The first winter thin out the branches, not leaving more than four to form the head of the tree. Cut these back at least one-half. In the second, third, and fourth years pruning of the tree should be continued to fashion it into the typical goblet form."
Frequent and thorough cultivation of the grove during the spring and early summer is recommended for Florida. Cultivation should be discontinued about the middle of July and a cover-crop then planted. This may be cowpeas, velvet-beans, beggarweed, or a natural growth of weeds may be allowed to develop. Commercial fertilizers are used to advantage.
F. H. Burnette 1 writes as follows on this subject:
"Good clean culture is all that is required, the same that is given in any well-cared-for fruit orchard. In our heavy lands, or on soils similar in character to the soils of the bluff lands of Louisiana, sodding-over should never be allowed, if good crops are desired. Any good complete manure may be used. A good crop of cow-peas turned under every two or three years will be highly beneficial.
"During the first three years the growth of the tree should be watched in order to build a symmetrical, upright tree. This is not easy, for some of the varieties spread too much, and the leading upright branches are often overloaded and become broken easily, or are headed back by careless removal of the fruit. Ordinarily, after they begin to bear, there is little need of pruning. The tendency to overbear is so strong that new wood is not produced in abundance, and the tree becomes dwarf-like. Systematic thinning of the fruit is necessary to control this, as it will not do to leave the thinning to natural causes, and depend upon the tree to throw off all the fruit it cannot well take care of. The weakened condition from overbearing results in a sickly tree which readily becomes a prey to diseases and insects, and it requires a careful observer to train his tree and thin the fruit to the proper amount."