How to Grow a Citrus Tree

Sun

Six to eight hours of direct sun is the minimum for serious fruit production and the sugar that makes the harvest worth growing. Anything less leads to thin foliage, sparse fruit, and tart underripe flavor. A south-facing exposure outdoors or the brightest window in a sunroom for a container tree gives the most reliable results.

A young grafted tree fresh from the nursery benefits from a week or two of light shading after planting to ease the transition, then gradually moves into the full position over a few more days.

Drainage

Free-draining soil is required. Citrus roots in standing water rot quickly, and wet feet through winter is a common reason a young tree fails in its first year. Dig a one-foot test hole and fill it with water. If it drains within a few hours, the spot is fine. If water sits overnight, build a raised mound 12 to 18 inches above grade and plant on top of it.

Soil

A sandy or loamy soil with plenty of organic matter is ideal. Work a few inches of compost into a wide area before planting. Citrus prefers slightly acidic soil, and an annual top dress of compost over the root zone keeps the chemistry in range. Container trees do best in a quality citrus or palm potting mix amended with extra perlite for drainage.

Space and protection

A standard Citrus tree needs 12 to 20 feet of clear space in every direction, depending on the variety and rootstock. A dwarf citrus needs 8 to 10 feet. Pick a spot with shelter from cold winter wind in the colder end of the zone range. The leeward side of a building or a south-facing wall provides several degrees of frost protection on cold nights.

Watering

Water deeply once or twice a week through the first growing season to establish the root system. Soak the root zone rather than splashing the leaves. Drip irrigation or a soaker hose at the base works best and keeps the foliage dry.

After the first year, water deeply once a week through dry weather and skip when rainfall covers the need. A container tree dries out faster and often needs water two or three times a week in summer. Uneven watering as fruit develops causes splitting and dropped fruit, so steady moisture matters most through the fruit set and fill window.

Feeding

Feed every six to eight weeks during active growth from late winter through early fall with a citrus-specific fertilizer. Citrus products include the extra micronutrients like iron, zinc, and manganese that citrus needs in higher amounts than most landscape plants.

Skip the once-a-year balanced lawn fertilizer, which is heavy on nitrogen and short on the trace elements citrus depends on. Stop feeding by late summer so the new wood hardens off before winter. A container tree benefits from a slightly lighter rate at slightly more frequent intervals than a tree in the ground.

Removing water sprouts and suckers

Cut any vigorous shoots growing from below the graft union as soon as they appear, since these come from the rootstock and produce inferior or no fruit. Pull or snip them off cleanly at the trunk. Check every couple of months through the growing season for new ones, especially on a young tree.

Opening the canopy

In late winter each year, remove anything dead, broken, or crossing through the middle of the canopy. Cut a few branches all the way out at the trunk to open the interior to light and air. The goal is a tree shaped like an open vase, with sunlight reaching every part of the canopy.

Citrus fruit forms on this year's new growth at the branch tips. Avoid shearing the canopy into a tight ball, since that removes the next round of fruiting wood. A naturally open canopy with light gaps between branches outproduces a tightly sheared tree.

Thinning a heavy crop

A young Citrus tree carrying too much fruit can break branches and ends up with small bland fruit. About four weeks after flowering, thin the developing fruit so the remaining ones are roughly 4 to 6 inches apart along the branch. The tree puts the same total energy into fewer larger fruit, the limbs handle the load, and the tree avoids the boom-and-bust cycle of one heavy year followed by nothing the next.

When it is ready

Citrus does not ripen further off the tree, so the fruit needs to stay on the branch until fully ripe. The cues vary by type. Most oranges and mandarins shift to a full deep color and lift off with a gentle twist when ready. Lemons hold on the tree for months after they color up and stay sweet-tart for the whole window. Limes are usually picked while still green, since fully yellow limes are past their peak.

Sample a few fruits from the sunny side of the tree first. Most varieties ripen unevenly across the canopy and are picked over several rounds rather than all at once.

Picking and storing

Twist gently rather than pulling, or use a sharp pruner to snip the stem flush with the fruit. A ripe Citrus fruit detaches with a slight twist, while one that resists needs more time on the branch. Hold picked fruit in a single layer in a cool spot.

Most Citrus fruit holds at room temperature for one to two weeks and in the fridge for several weeks. Juice and zest also freeze well for long-term storage. A serious harvest year often produces more than the household can eat fresh, and zest and juice frozen in bags or cubes carry the flavor through to the next bloom.

Yield expectations

A young dwarf Citrus tree on a balcony or patio can produce 5 to 15 pounds of fruit a year by year four or five. A standard tree in a warm climate yard can produce 50 to 200 pounds of fruit a year at full maturity, with the higher end on heavy croppers like Valencia oranges. Yields swing with weather, pest pressure, and how regularly the tree was thinned and fed.

Yellow leaves between green veins

Iron, zinc, or manganese deficiency, all common on alkaline or sandy soil. Switch to a Citrus-specific fertilizer that supplies these micronutrients, and apply a chelated micronutrient foliar spray for fast correction. Renew acidic mulch like pine bark or pine needles over the root zone.

Dropping fruit before ripening

Some natural drop happens after bloom and again in early summer as the tree balances its load. Heavy drop late in the season usually points to uneven watering, sudden temperature swings, or nutrient stress. Mulch two to three inches deep, water deeply through dry spells, and stay on the Citrus-specific feeding schedule.

Cold damage on leaves and fruit after a chilly night

Brown blotches or fully collapsed new growth following a frost. There is no quick fix once the damage is visible. Cut nothing until late spring, since damaged leaves still feed the tree while new growth pushes from healthy buds. Plan winter protection or container culture in zones colder than the variety's safe range.

Sticky residue and black sooty mold on leaves

A symptom rather than the underlying problem. The mold grows on the sugary residue left by scale, aphid, mealybug, or whitefly feeding above. Identify and treat the underlying pest with horticultural oil or insecticidal soap, and the mold washes off with soapy water once the pest is gone.

Bumps on stems and leaves

Scale insects feeding on sap. Wipe individual scales off with a cotton swab dipped in rubbing alcohol. Heavier infestations respond to horticultural oil sprayed when the tree is dormant or in cooler weather, since hot-weather oil applications can scorch the leaves.

Aphids and curled new leaves

Small green or black insects clustered on shoot tips and the undersides of new leaves in spring. Knock them off with a strong spray of water. Heavy infestations respond to insecticidal soap. Avoid heavy nitrogen feeding, which produces the soft fast growth aphids prefer.

Squiggly silver trails through new leaves

Citrus leafminer, a small fly whose larvae tunnel inside young leaves. Damage is mostly cosmetic on a healthy mature tree, but a young tree can lose enough leaf surface to slow growth. Trim heavily mined new growth and discard it. A spinosad spray timed to new flushes of growth reduces the next generation.

Greasy spots on the leaves

Greasy spot disease, a fungal infection most common in humid climates. Yellow patches on the upper leaf surface develop into greasy raised spots on the underside. Rake and dispose of fallen leaves to break the disease cycle, and apply a copper spray in early summer in problem areas.

Lopsided fruit with bitter green flesh

Symptoms of citrus greening disease (also called HLB), a serious bacterial disease spread by the Asian citrus psyllid in Florida, Texas, California, and other regions. There is no cure for an infected tree, and the eventual decline can take years. Report suspected cases to the local agricultural extension office, since this disease threatens entire regional Citrus industries.

Splitting fruit on the tree

Caused by uneven watering during fruit fill, when a long dry spell is followed by heavy rain or a deep watering. The peel cannot stretch fast enough to match the swelling flesh inside. Mulch two to three inches deep and water deeply through summer dry spells to keep soil moisture even.