Fruit and Nut Crops

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Plum

Plum production has good potential for commercial growers and homeowners in Florida and other mild winter areas throughout the Gulf coast. However, most seasonal plums on the market are from California and will not consistently perform well enough in Florida to produce fruit. From 1998 to 2001, plum cultivars have been released from the University of Florida's breeding program that adapt to our mild winters and high disease pressures. Because they have cropped reliably and produced high quality fruit, these cultivars are recommended for trial in Florida. The names of all University of Florida plum cultivars begin with the prefix 'Gulf.' These cultivars are Japanese type plums (Prunus salicina Lindl.) and have resistance to plum leaf scald (Xylella fastidiosa) and bacterial spot (Xanthomonas campestris). Fruit size is satisfactory (about 1½ to 2 in. diameter) and fruit quality is good. They ripen in early to late May or about two weeks before California plums.

Fertilizing

Plums are generally fertilized with a 12-4-8 fertilizer which is broadcast under the canopy of the tree.  Fertilizer with added micronutrients is recommended.  Fertilizer amounts and application times vary based on the age of the tree:

Year 1:  Newly planted trees should be fertilized in:

  • February: 1/8 pound (1/4 cup) per tree of 12-4-8 fertilizer with micronutrients.
  • May (late): 1/4 pound (1/2 cup) per tree of 12-4-8 fertilizer with micronutrients.
  • July: 1/2 pound (1 cup) per tree of 12-4-8 fertilizer with micronutrients.

Year 2+:  Fertilize in late January and again in May using 1 to 1.5 pounds (2-3 cups) per tree of 12-4-8 fertilizer with micronutrients.

Training

Plum trees are trained into a modified leader system.  After planting, training begins the first year by removing at least 1/3 of the top to balance it with the root system. This is called heading back. Ideally, trees should be 2½ to 3 ft. tall after heading back. Most of the buds will break within 1 ft. from the top. Remove all buds below 18 in. height. Generally, 3 to 5 bud-shoots are equally spaced around the trunk to form the scaffold limbs. Shoots should be encouraged to grow at a large angle from the trunk. Scaffold limbs and vigorous shoots may be trimmed back or removed if they tend to dominate the center. Branches that grow toward the outside form a strong tree framework. During the second and subsequent years, secondary limbs will develop from the primary 3 to 5 scaffold limbs.

Pruning

After the trees have been trained, pruning to maintain the open center of the canopy should be done during the dormant season (January-February).  This will allow for light penetration which will stimulate growth of new fruiting wood and improve fruit quality.  Unlike peaches, which are shaped like the outside of a bowl, the center of a plum tree is not removed.  Eliminate branches that cross or rub, and control the overall height of the tree canopy by topping branches and whips to around 7 feet so that fruit can be picked without the use of ladders.   Many plum cultivars set fruit on long whips. These whips are cut back to 1-3 ft. to limit fruit load and prevent breakage. In addition to forming fruit on whips, older trees set fruit on 2-4 ft. spurs, so some of these can be removed to limit crop load.  Lighter pruning for the same reasons can be accomplished during summer after fruit is harvested. 

Fruit Thinning

Thinning the crop load is necessary to develop marketable size fruit.  While pruning is used to reduce the amount of hand fruit thinning that would be necessary, fruit will also need to be removed by hand picking or beating the limbs with a piece of rubber hose or PVC pipe.  This is done about a month after bloom when fruit are 3/8 to 1/2 inch diameter. The pit must not be hard or the thinning will not be as effective. Bloom thinning or thinning when the fruit are too small is not done because plum trees will normally shed a large quantity of flowers and small fruit. Ideally, fruit should be spaced 3 to 6 inches apart. If the crop is light, only heavy clusters should be broken up, leaving fruit spaced closer. Since plums have a long bloom period, thinning cannot be done all at once. It lasts for a month and requires at least three visits to each tree. Generally all of the late bloom will fall off and not set fruit. With this in mind it is important to judge what the crop load will be and thin fruit accordingly. Thinning should not be done until most of the danger of freezing temperatures in late winter/early spring is over. 

UF/IFAS Publications

Growing Plums in Florida

Prunus mexicana: Mexican Plum

Prunus umbellata: Flatwoods Plum

Prunus cerasifera 'Thundercloud': 'Thundercloud' Cherry Plum

Prunus cerasifera 'Atropurpurea': Pissard Plum

Peach, Plum, and Nectarine Pest Management

Weed Management in Plums

UF/IFAS Sites

Stone Fruit Production in Florida - UF Horticultural Sciences

County Fact Sheets & Articles

Useful Links