The papaya is tropical in its requirements, but it can be grown in regions where light frosts are experienced. It prefers a warm climate and rich, loamy, well-drained soil. In southern Florida it grows best on hammock soils, but it is successful on "high pine" lands if properly fertilized. On the Florida Keys the plant has become thoroughly naturalized and springs up wherever a clearing is made, the seeds being scattered by birds and other agencies. While commercial papaya-culture probably should not be attempted north of Palm Beach, good fruits are occasionally produced in the central part of the state when a mild winter allows the plants to reach fruiting age without injury.
In California the cool nights do not permit the fruit to mature perfectly. It has been observed in the tropics that papayas ripened in cool weather are insipid or squash-like in flavor. The best situations in southern California are the protected foothill regions, where the heat during the summer months is more intense than on the seacoast. An old tree at Hollywood, near Los Angeles, bore fruit several years, but finally succumbed to the cold rains of winter which cause the plants to rot off at the base, especially if the drainage is in the least defective.
Higgins and Holt, whose bulletin "The Papaya in Hawaii" 1 is the most valuable contribution yet made to the literature of papaya-growing, have the following to say concerning climate and soil:
"In regard to rainfall and moisture requirements, the plant is able to adapt itself to a wide range of conditions, and when established suffers much less from a shortage of water than the orange or the avocado, but makes beneficial use of a large amount if supplied. Yet, withal, it is one of the most insistent plants in the matter of drainage. In waterlogged soils the papaya makes a spindling growth and drops its lower leaves prematurely, while the remaining foliage becomes yellow, the whole plant indicating an unhealthy condition.
"There are few, if any, soils in which the papaya will not grow if aeration and drainage are adequately supplied. Most of the plantings at this station are upon soils regarded as unsuitable for other fruit trees and upon which the avocado is a failure. . . . They are very porous, permitting perfect drainage and aeration. Rich soils give correspondingly better and more permanent results if they permit of the free passage of water and entrance of air."
For a permanent orchard, the plants should be set not less than 10 feet apart. The papaya is short-lived, and will not usually remain in profitable bearing more than three to five years. That it is extremely simple of culture is proved by the ease with which it becomes naturalized in tropical regions, and by the thriftiness of the wild plants which spring up everywhere along the roadsides.
1 No. 32 of the Hawaii Exp. Sta.
P. J. Wester writes as follows regarding the planting and care of papayas:
"When the plants have attained a height of about 3 to 4 inches, they are ready to be transplanted to the place where they are intended to grow.
"Unless the transplanting has been preceded by a good rain, the plants should be thoroughly watered before they are removed from the seed-bed. In order to reduce the evaporation of water from the plants until they are well established in their new quarters, about three-fourths of the leafblades should be trimmed off.
"In transplanting, take up the plants with so large a ball of earth that as few roots are cut or disturbed as possible. Do not set out the young plant deeper in the new place than it grew in the nursery; firm the soil well around the roots, making a slight depression around the plant, and water it thoroughly.
" In order to protect the tender plant from the sun until it is established, it is well to place around it a few leafy twigs at the time of planting. It is well to set out three plants to each hill, and as the plants grow up and fruit, to dig out the males or the two poorest fruiting plants.
" If the plants cannot be set out in the field at the time indicated, transplant them from the seed-bed to a nursery, setting out the plants about 8 to 12 inches apart in rows a yard apart, or more, to suit the convenience of the planter. While the best plan is to set out the plants in the field before they are more than 12 inches tall, the plants may be transplanted to the field from the nursery with safety after they are more than 5 feet high, provided that all except young and tender leaf-blades are removed, leaving the entire petiole, or leafstalk, attached to the plant; if the petiole be cut close to the main stem, decay rapidly enters it. If the entire petiole is left it withers and drops and a good leaf scar has formed before the fungi have had time to work their way from the petiole into the stem of the plant.
"When a plant has grown so tall that it is difficult to gather the fruit, which also at this time grows small, cut off the trunk about 30 inches above the ground. A number of buds will then sprout from the stump, and will form several trunks that will bear fruit like the mother-plant in a short time. These sprouts, except two or three, should be cut off, for if all are permitted to grow the fruit produced will be small."
When first set out in the field, the young plants should be watered every day or two; after a few weeks have elapsed and they have become established, waterings may be less frequent.
Mature plants should be irrigated liberally unless rainfall is abundant. Since they are gross feeders, stable manure or commercial fertilizers should be supplied liberally. This is particularly true of plants which are grown on the sandy lands of southeastern Florida. Organic nitrogen is especially desirable.