HOME FRUIT PRODUCTION-LIMES
Julian W. Sauls, Ph.D.
Professor and Extension Horticulturist
Texas Cooperative Extension
Limes are second only to lemons in terms of importance as a flavoring agent for foods, drinks and other, non-edible, products for home and industrial use. Tenderness to cold weather precludes commercial lime production in Texas, but limes are commonly grown in home plantings in the Lower Rio Grande Valley.
Lime trees are extremely cold sensitive and cannot be expected to survive the freezing temperatures that occur through most of Texas unless special efforts are provided for freeze protection. Such protection is necessary even in the Lower Rio Grande Valley during major freeze events.
SOILS AND SITE SELECTION
Lime trees are well-adapted to soils having good internal and surface drainage. Growth on heavy clays or poorly-drained soils will be reduced and problematic, as limes do not tolerate flooding conditions. Nutritional deficiencies can occur on soils high in caliche.
In the home landscape, lime trees should be planted on the south or southeast side of the house in order to take advantage of the cold protection provided by the house. For optimum growth and production, the trees should be planted in full sun.
VARIETIES AND TYPES
Mexican lime is also known as key lime and West Indian lime. It originated in Asia, was introduced to the Iberian Peninsula and North Africa by Arab traders and was brought to the Americas during the early sixteenth century by Spanish and Portugese explorers. It became naturalized in the West Indies, south Florida and some Caribbean countries.
The tree is somewhat small and bushy, with slender branches, having short spines (thorns). A thornless selection is somewhat more desirable but less productive. The fruit is small, rarely achieving 2 inches in size, round to oval in shape, and contains a moderate number of polyembryonic seeds. The rind is thin and yellow at full maturity, while the juice is faintly greenish yellow, highly acid and has the distinctive lime aroma.
Tahiti lime is also called Bearss lime and Persian lime. Although its exact origin is unknown, it appeared in a home planting is California about 1875 and is believed to have originated from seed of citrus fruit imported from Tahiti to San Francisco sometime after 1850. It is also believed to be of hybrid origin.
The tree is somewhat larger than Mexican lime, achieving heights of 20 feet under optimum conditions. The branches are variably thornless or armed with quarter-inch thorns--even on the same tree. The fruit is oval, about 2.75 inches long and up to 2.5 inches in diameter, but it will get even larger if left too long on the tree. It is characterized by the presence of a nipple on the blossom end of the fruit. The rind is thin, smooth and dark green at commercial maturity, becoming very light green to yellow at full maturity. The fruit is normally entirely seedless, although one or two seeds may occur when grown in close proximity to other citrus. The juice is greenish and acidic, having the distinctive lime aroma.
Giant key lime was released by ARS-USDA in 1994. It is a spontaneous autotetraploid Key lime seedling that was selected in 1973. The major difference in this lime is that its fruit are more than twice the size of common Mexican limes. Budwood is not available in Texas, so it is only reported as an item of interest for the future.
Rangpur lime is an acidic fruit that more closely resembles mandarins than limes. Its fruit are highly acid, very seedy, with a loose, thin rind. It is primarily used as a rootstock for other citrus and as an ornamental tree.
Palestine sweet lime is not a true lime. Its fruit are pale yellow, juicy and subacid in flavor. Its primary use is as a rootstock, although there is some production in the Mediterranean, in India and in Latin America.
Limequats such as 'Eustis', 'Lakeland' and 'Tavares' are hybrids between Mexican lime and kumquat. The fruit closely resembles Mexican lime and the trees are somewhat more cold hardy than limes--though not nearly so hardy as kumquats.
Mexican lime and the limequats are sufficiently small trees that they can be readily grown in large containers in areas where cold temperatures would preclude their being grown in the ground.
Either T-budding or inverted T-budding onto sour orange seedlings is the preferred means of propagation in Texas. Mexican lime can also be grown from seed. Air layers (marcots) of both Mexican lime and Tahiti lime are successful. The expected life of seedlings and marcots is shortened considerably by the lack of resistance to Phytophthora root and foot rot afforded by trees budded onto sour orange rootstocks. Given the limitation of Phytophthora, both seedlings and marcots will regrow true-to-type if killed to near the ground by severe freezing temperatures.
PLANTING AND ESTABLISHMENT
For the most part, lime trees will be purchased from a nursery rather than grown at home. Generally, the trees will be container-grown in a soilless medium--which makes the trees rather difficult to establish without special care. At planting, use a gentle stream of water from the garden hose to wash an inch or so of the medium from all around the root ball, thereby exposing the peripheral roots. Thus, the outer roots are placed in contact with the soil of the planting site and growth commences almost immediately.
Under no circumstances should soil around the proposed planting site be removed to form a shallow basin for watering--to do so almost guarantees that the young lime tree will contract foot rot and die before its fifth year. The soil in the planting site should be at least as high as the surrounding yard, if not higher. In addition, the tree should be set slightly higher than it was in the nursery container to assure that the budunion will remain well above the soil.
Mixing topsoil, compost, peat or other materials with the backfill soil is neither necessary nor desirable in good soils. Set the tree in the hole, backfill about halfway, then water sufficiently to settle the backfill around the lower roots. Finish backfilling the hole and then cover the root ball with about in inch of soil to seal the growing medium from direct contact with the air and thereby prevent rapid drying of the root ball.
To facilitate watering, bring soil from the garden or elsewhere to construct a watering ring atop the ground around the newly planted tree. The ring should be about two feet across and several inches high and thick. To water, just fill the water ring immediately after planting. After the water soaks in, it may be necessary to add a little soil to any holes formed as the soil settled around the roots.
The watering interval should be every few days for the first couple of weeks, then gradually increased to 7 to 10 days over the next couple of months. The watering ring will gradually melt into the surrounding soil, at which time the young lime tree can be considered to be established.
All weeds and lawngrass should be completely eliminated inside the watering ring, as the developing lime tree cannot compete well. A systemic, contact herbicide will work very well, so long as it is not allowed to contact the young tree leaves or green bark.
The best way to protect the young trunk from herbicide damage and, at the same time, to prevent sprouts along the trunk is to crimp an 8-inch by 18-inch piece of heavy duty aluminum foil around the trunk from the ground to the scaffold limbs. Fold the foil lengthwise, bring the long edges past the trunk on both sides, crimp the two edges together and lightly squeeze the foil around the trunk.
While mulching of citrus trees is commonly practiced in southeast Texas where there is an abundance of materials to use, mulching is not recommended for citrus because it increases the possibility of the tree contracting foot rot, for which there is no cure. If you insist on mulching, keep the mulch at least a foot away from the trunk.
Fertilizer should be withheld until after growth commences. During the first year, a single cupful of ammonium sulfate (21-0-0) split into three or four applications is adequate. Use two cups in the second year and three in the third. Just scatter the fertilizer on the ground around the tree and water thoroughly. In areas other than the Valley, use whatever fertilizer analysis that is in general use in the area for trees and shrubs--simply adjust the rate based upon nitrogen content.
Cold protection measures for lime trees will be required sooner or later. Soil banks are very effective for young trees; the soil should be put up about Thanksgiving and left in place until early March. Exercise care when taking down the soil bank, as the bark underneath will be extremely tender.
Blankets, tarps or similar covers are also very effective and have the advantage of being quickly draped over the young tree. The corners should be stretched outward and tied down. More elaborate protection can be provided by erecting a frame structure of wood or PVC pipe over the plant to facilitate the use of plastic or large tarps during particularly severe cold weather. Supplemental heat can also be provided under the covers; incandescent bulbs and heat lamps are useful.
MATURE TREE CARE
Watering should be slow and thorough; probably every couple of weeks would suffice in any but the very sandy soils. Nutrition should continue at about one cup of ammonium sulfate per year of tree age annually in split applications in February, May and September, i.e. a 6-year-old tree should receive about six cups of 21-0-0 for the year. Adjust the rate for other fertilizers based upon the relative nitrogen content.
Lawngrass should be kept back about a foot from the canopy of the tree. Other than cold damage, no pruning should be necessary, as the lime tree will develop its natural shape without pruning. While mulching is not recommended for citrus trees, if you must mulch, keep the mulch at least one foot away from the tree trunk.
PRODUCTION, MATURITY AND USE
Either Mexican lime or Tahiti lime will produce more fruit than most families could use, given modest care and freedom from cold damage. Budded trees will commence to bear in the third year after planted, marcots in the second year. Primary production will be in the summer months, but some fruit can be borne year round.
Mexican lime achieves maximum flavor and juiciness when the rind becomes yellow, while Tahiti lime fruit are best just before they become completely yellow. Because limes begin to drop after the rind becomes yellow, the juice can be extracted for freezing in ice cube trays. After freezing, the cubes can be stored frozen for later use.
Aside from their obvious use in the flavoring of beverages such as tea and water, limes are also used in cakes, pies, candies and marinades and flavoring for fish, meat and poultry.
Limes are afflicted with the same pests and diseases as other citrus, so the reader is referred to Home Fruit Production--Citrus, Table 2. In addition, limes can develop stylar end breakdown in which some juice vesicles rupture, allowing the juice to collect at the stylar or blossom end of the fruit. Because of its acidity, the juice will cause breakdown of the rind at the blossom end. To reduce the problem, delay harvest until ate morning or afternoon, do not pick after a rain or when the fruit is wet. Too, handle the fruit gently to avoid bruising.
One pest not discussed in the HFP-Citrus publication is Asian citrus leafminer, as the pest arrived in Texas about 1994. This leafminer attacks the new flushes of growth when the developing leaves are only about an inch long, leaving serpentine trails from their feeding and causing stunting and distortion of the leaf. Occasionally, trails or mines occur on fruit as well. Each growth flush is susceptible to attack and limes may have as many as eight or 10 growth flushes annually. The spring flush is least damaged, since the leafminer does not overwinter well, but the later flushes can be devastated.
There are no chemical controls available for home use, although citrus spray oils do deter infestation if the application is timed to the development of a new flush of growth. Otherwise, it is best to try to ignore the damage; leafminer will not kill the tree and indiscriminate spraying kills a lot of the natural predators and parasites that help to keep leafminer populations down.
There are very few lime tree problems that are life-threatening--and the home gardener cannot do anything about those anyway. Many of the rest of the insects and diseases that afflict lime trees can generally be ignored in the home garden, as blemishes to the peel affect only the appearance, and, in some cases, size of the fruit.
If one must spray, first identify the problem, then select the appropriate material and apply it properly and at the appropriate time to control the pest while minimizing damage to the complex of beneficial organisms that exist in citrus.
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This page revised July 29, 2005