Notes:

Care and Planting

CLIMATE

Mandarins are grown in tropical and subtropical areas worldwide, although best color and quality usually occurs under subtropical conditions. As a group, mandarins are among the most cold hardy of citrus fruits, being second only to kumquats. Small orchards of tangerines in the Carrizo Springs area and of satsumas in southeast Texas were fairly common until the severe freezes of the 1980's. Few of those orchards remain today, but interest in mandarins remains high for home production. Protection during severe freezes will be essential to successful mandarin production.

SOILS AND SITE SELECTION

Mandarins are well-adapted to all well-drained soils in virtually all of Texas along and south of U.S. Highway 90 from Del Rio to Orange--depending on rootstock. In southeast Texas, growers prefer trifoliate orange rootstock because of the additional cold hardiness which it imparts to the tree. However, trifoliate orange is poorly adapted to the saline conditions and alkaline soils which predominate in south Texas where sour orange is the rootstock of choice. Trees on trifoliate are considerably smaller than trees on sour orange, with those on 'Flying Dragon' trifoliate being even smaller than on other trifoliate rootstocks. Smaller trees are more easily protected during severe freezes, but smaller trees are also less productive.

In the home landscape, mandarins should be planted on the south or southeast side of the house for maximum protection from cold weather. Overhanging trees will provide additional cold protection but the competition for light, water and nutrients will reduce mandarin tree growth, production and fruit quality.

PLANTING AND ESTABLISHMENT

For the most part, mandarin 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 mandarin tree will contract foot rot and die before its fifth year. In wetter, lower areas in southeast Texas, the use of raised beds is recommended. 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 mandarin tree can be considered to be established.

All weeds and lawn grass should be completely eliminated inside the watering ring, as the developing mandarin 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 for home use. 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 mandarin 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 tree 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 mandarin 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

Mandarins are highly productive for the size of the tree, but most are subject to strong alternate bearing, which results in significant limb breakage during the heavy crop seasons (unless some means of limb support is provided). Because most mandarins do not store well on-tree after they reach maturity, production is generally greater than the average family can use during their relatively short season.

While the mandarins are noted for their bright peel color, it is not uncommon for the fruit to attain good eating quality before the peel loses its green color. In some cases, the flesh many become "ricey" by the time the peel achieves normal color--especially in those varieties which mature in September-November. Maturity is based on "eating quality" of the fruit--not on peel color.

Mandarins are primarily eaten fresh. However, in times of plenty, excess fruit can be sectioned and canned or frozen or it can be juiced and frozen.