Time to Plant and Fertilize Citrus Trees

Now is the recommended time to plant citrus trees in our area. A well-drained soil, high in organic matter and slightly acid to neutral, is desirable for citrus. The site should provide full sunlight. In most cases, homeowners are limited to sites in the yard where citrus can be planted. The site with the most sun should be selected for a citrus planting. Citrus trees require good drainage and should not be planted on heavy clay soils with poor internal drainage. If this is the case, they should be planted on a mound or row 8 to 12 inches high to reduce potential root rot disease.

The best time to plant citrus trees is now as trees planted after December can withstand a freeze in February better than earlier-planted trees. A 2- to 4-foot tree with three to four well developed upward growing side branches 18 to 24 inches above the ground is the ideal tree for home plantings.

The root system of the young trees should be inspected before planting. Trees that have bent or circled root systems will be stunted and grow poorly. Nurserymen and growers often called this condition ‘J’ rooted. Prune any damaged roots back beyond the damaged area. If container-grown trees have a taproot curled in the bottom of the container, cut this root off at the point where it begins to curl. The tree will grow a new taproot. Separate and trim the roots of container trees that are root bound.

Dig a hole slightly larger than the container. Place the tree in the hole at the same depth it was growing previously. If holes are dug too deeply trees may settle after watering. Trees set too deeply may die. Container trees should have the top of the soil flush with the top of the hole.

Bare-rooted trees should have soil placed underneath them in a manner to allow the spreading of the roots in a natural position with no bending or crimping. Before completion of backfilling, add water to settle the soil and eliminate air pockets around the roots. After watering, fill the hole to completion, and water again.

Different types of citrus require different spacing. In most cases, homeowners are limited to the space in their yards for citrus trees. The site that will provide the most space should be selected. Trees planted too closely together or against buildings will have limited sunlight and air movement that will restrict the growth and yield of the tree and enhance the development of pests. Spraying for pests, pruning and harvesting the fruit are difficult on trees planted too closely together.

Navel oranges, grapefruit and other oranges are the most vigorous citrus trees. They require at least a 30- to 40-foot diameter circle. (Example: Allow at least 15 to 20 feet from any building or large tree on each side of the navel orange, grapefruit or other round oranges). A satsuma is not as vigorous as oranges or grapefruit and requires a 20- to 30-foot circle in diameter; kumquats and lemons need only a 15-to 20-foot diameter circle.

The best citrus rootstock for the Louisiana home citrus orchard is trifoliata (Poncirus trifoliate Rubidoux). This rootstock is the most cold hardy of the citrus rootstock, resistant to rots and tolerant of wet soils. Homeowners should ask the nursery to obtain trees on trifoliate, but they are at the mercy of the nursery on the rootstocks of the citrus trees they buy.

One of the major rootstocks used in the Louisiana citrus nursery trade is Swingle citrumello. This very vigorous rootstock produces a large budded tree in one year. Trees budded on Swingle rootstocks are vigorous and produce good crops of high quality citrus. The main drawback of using Swingle rootstock is that it is not as cold hardy as trifoliata.

In the last several years, several nurseries have been grafting citrus trees on a dwarf rootstock known as Flying Dragon Trifoliata. Dwarf trees are ideal for homeowners with limited space. Good crops of oranges and satsuma can be made in a circle only 10 feet in diameter. Ask your local garden centers and nurseries to obtain trees budded on the dwarf Flying Dragon Trifoliata rootstocks.

Citrus trees require annual fertilization for good growth and high yields of good size, high quality fruit. Newly set trees should not be fertilized until they show signs of growth, usually six weeks after they are set in the spring (mid March). On newly planted trees, apply 1/2 pound of 8-8-8 or 13-13-13 per tree in mid March.

After the second year, fertilize citrus trees in late January or early February. Apply 1 to 1 1/2 pounds of 8-8-8 or 13-13-13 per year of tree age up to 12 years. Increase the rate of fertilizer l -1 1/2 pound per year as the tree gets older. A one-year-old tree gets 1 to 1 1/2 pounds of 8-8-8or 13-13-13, and a 5-year-old tree gets from 5 to 7 1/2 pounds. The fertilizer rate is increased each year until the tree is 12 years old. Trees 12 years old and older are at the top limit of fertilizer and should receive 12 to 18 pounds of 8-8-8 or 13-13-13 per tree.

A simple fact to remember is that one pint of 13-13-13 weighs about 1 pound and a quart weighs 2 pounds. (Example: A one-year-old tree will require 1 pound or one pint of 13-13-13, and a 4-year-old tree will require 4 to 6 pounds or two to three quarts of 13-13-13.). Broadcast the fertilizer beyond the spread of the limbs where most of the feeder roots occur.

A general rule when fertilizing trees is to put your left shoulder near the outer branches and hold the can of fertilizer in your right hand. You can simply walk around the tree and evenly spread the fertilizer in a 12- to 18-inch band on the outer branches of the tree. This technique will ensure that the fertilizer is placed a safe distance from the tree.

Avoid fertilizing citrus trees after the end of June. Late fertilization will encourage vigorous growth, delay fruit maturity and decrease the cold hardiness of the tree. Homeowners are also encouraged to pay strict attention to the amounts of fertilizer applied to citrus trees.

Amounts above those recommended will encourage vigorous growth, delay fruit maturity and decrease cold hardiness. Vigorous growth can result in extensive freeze damage or death of the trees, even in a moderate freeze.

Good nursery trees usually have a framework already developed when purchased. Homeowners should try to select a 2 to 4 foot tree. Trees should be pruned after planting and before growth starts in the spring. The top of the tree should be removed 18 to 24 inches from the ground at a site where there are three or four evenly spaced wide-angle lateral branches with an upward-growing pattern that has developed. All growth developing below this framework should be removed.

The primary purpose of pruning young nonbearing trees is to shape the tree so that scaffold branches will be well distributed. This initial pruning helps bring the tops of the plants and the root system into balance. It also stimulates good scaffold branch development. If scaffold branches are selected properly, the weak narrow crotches and downward growing branches can be eliminated and future breakage under heavy fruit loads can be avoided. Proper selection of scaffold branches also will reduce the large pruning cuts in the future years.

After the selection of the scaffold branches, only limited pruning is needed on citrus. All pruning on older trees should be done in February. Pruning trees of bearing age is practiced to thin out thick growth to spray and harvest easily. The removal of long vigorous growing shoots that stick up at the top of the tree will help to control the size of the tree. These long shoots should be traced to where they originate on larger branches and cut off flush at the point of attachment.

Dead branches, branches crossing over each other, water sprouts arising from the center of the tree and branches touching the ground should be removed. When pruning, cut all limbs flush at the point of attachment.

Freeze-damaged trees should not be pruned until the extent of cold damage has been determined. Normally, the damage is not evident until July and August after the second flush of growth. Pruning a freeze-damaged tree consists of removing the dead wood to the point where the live wood starts.

Question of the Week: How can a gardener adjust water pH levels prior to mixing an insecticide into the tank?

Answer: Home gardeners can purchase a “buffer” from a garden center or feed store and follow label directions to adjust water pH. It will also be helpful if they have a pH meter or litmus paper to help determining initial and adjusted water pH. The range when using insecticides should fall within the range of 5.5 to 6.0 for maximum effectiveness.

All pesticides have both benefits and risks. Benefits can be maximized and risks minimized by reading and following the labeling. Pay close attention to the directions for use and the precautionary statements. The information on pesticide labels contains both instructions and limitations. Pesticide labels are legal documents and it is a violation of both federal and state.

For more information on these and other horticultural topics, call the Lafourche Extension office at 985-446-1316, email me at bhfletcher@agctr.lsu.edu or come by 402 West 5th Street in Thibodaux. You can also visit our web site at www.lsuagcenter.com.