Regarding the best time to plant avocados in southern Florida, Krome says:
"I have planted at least a few avocados every year since 1905 and these plantings have been made during every month of the year. When I have the land prepared and the trees available I do not hesitate to plant at any season but I endeavor to make my arrangements so that all of my main settings will be between the 15th of September and the 20th of October, i.e. during the last month of the regular rainy season, after the hottest weather of the year is past. When avocados are planted in the spring in Florida they have immediately ahead of them our most trying months of drought, March, April and usually most of May. During this period the plants must be watered with the greatest regularity or they will suffer. Following the dry weather of our spring months the trees have the benefit of the rainy season but in Florida our rains are quite frequently uncertain during July and August and there will be need for watering any trees planted during the preceding three or four months. For the past month (June) we have averaged at least two applications of water per week to avocados planted during March, April and May. These spring-planted trees must also withstand the sun's rays during our season of greatest heat and shading is usually a necessity if sun-scald is to be prevented. There are no good reasons why trees thus planted should not be brought through to fall in good condition but it requires a great deal of additional work and expense as compared with trees planted during the latter part of September or first half of October, when rains are of almost daily occurrence and the plants after setting need very little further attention. Furthermore, spring-planted trees very seldom make sufficient growth over those planted in the fall to acquire any considerably greater degree of resistance to cold the following winter. I have always found that trees planted in March fare just about as badly as those planted in September when we have severe cold the next winter."
In California it is not desirable to plant earlier than March, because of danger from late frosts. April and May are good months, and November planting has been successful. Planting in midsummer is to be avoided, but it may be done successfully if the trees are carefully shaded and watered until they have become established.
Avocados are sometimes interplanted with other fruit-trees, such as grapefruit and mangos. This is scarcely to be recommended, since avocados require different cultural treatment.
In Florida, budded avocados are planted 20 by 20 feet (108 to the acre) to 26 by 26 feet (64 to the acre), some growers preferring to have the trees close together so that they will soon shade the ground, others desiring to give more room for ultimate development. On light sandy soil the trees are usually set closer than on heavy soils, 20 by 20 feet being a suitable distance in the first case, 24 by 24 in the second. In California they should not be spaced closer than 24 by 24 feet, making 75 to the acre; 30 by 30 feet (48 to the acre) is preferable.
Holes for planting should be prepared a month in advance, with a small quantity of fertilizer incorporated in each. Barnyard manure is commonly used for this purpose in California, while South American goat manure and pulverized sheep manure, 2 or 3 pounds to each hole, have proved satisfactory in Florida.
In planting, the tree should be set so that the point of union between the bud and the seedling stock is slightly above the surface. Deeper planting may not be objectionable in California, but in Florida shallow planting seems to be best. A liberal watering should be given immediately after planting.