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Growing Lemons: Citrus limon

Botanical Overview

According to genetic analysis, Lemons, members of the Citrus family (Rutaceae) and Citrus genus, are complex hybrids arising from mandarin, pomelo, and citron ancestors, refined by thousands of years of cultivation. Citrus limon, the true Lemon, is widely grown commercially.

Description

Form: A shrub or small tree.
Lifespan: 50-100 years.
Leaf retention: Evergreen.
Growth rate: Moderate.
Mature Size: 10-20' high and 7-15' wide.
Flowers: White on top, five petals, fragrant.
Bloom: In mild winter regions, possibly all year.
Self-fruitful: All lemon cultivars self-pollinate.
Years before fruiting: for trees with grafted rootstocks, 2-3 years. Discard any small fruits started in the first three years, which will probably be dropped before maturity anyway, so the plant can put more energy into growing roots and branches. A tree grown from seed will take 5-15 years to start fruit.
Fruit: Generally oval shaped, sometimes with pointed ends. When ripe, the skin is yellow and aromatic. The yellow flesh, very sour in the 'Lisbon' but slightly sweet in the 'Improved Meyer', may contain seeds or be seedless. The entire fruit is edible except for the seeds.
Months for fruit to ripen: 6-9. Lemons are ripe when their skin is entirely yellow. Their flavor does not ripen further after harvest, but they can be made to soften and finish becoming all yellow when picked early if the skin has some yellow. Place them in a window where they can receive direct sunlight. Early picked fruit ripened inside will not taste as good as one fully ripened on the tree, however. Do not allow lemons to remain on the tree more than two weeks when ripe, or they will become dry and tasteless.
Storage after harvest: Lemons last about a week at room temperature and four weeks sealed in a plastic bag in the refrigerator.
Leaves: Glossy dark green, broadly lance-shaped.
Stems: Twigs may have sharp thorns.
Roots: Usually grafted onto a hardier rootstock. These roots will typically extend past the drip line and grow at least 2' deep.
Cultivars of Note:
'Lisbon' blooms in the spring, bears most of the year, has oblong fruit with a prominent nipple, is thorny, vigorous and productive, and being widely grown, is the standard commercial lemon.
'Eureka' blooms fall and spring, produces year-round, and has few seeds. Compared to 'Lisbon', it is slightly less cold-hardy and less thorny, less resistant to insect infestation and neglect, and shorter lived.
'Pink Variegated Eureka' has green and yellow striped fruit ripening to all yellow, pink flesh, blooms and fruits nearly year-round, has few seeds and variegated leaves, and is less vigorous than the typical 'Eureka'.
'Improved Meyer', a cross between two citrus cultivars, does not have the parentage of true lemon. It withstands a wider range of heat and cold, has a different flavor – sweeter and less acidic, bears year-round, has many seeds, but its thin rind has little lemon oil flavor, making the grated rind useless in recipes.
'Sweet Lemon' is a generic name for hybrids that are low acid. One such hybrid, with the non-official Latin name Citrus ujukitsu, is called Ujukitsu Sweet Lemon. This is a small citrus shrub with weeping branches. Growing very slowly, it is cold-hardy in USDA zones 9-10. The large, pear-shaped, mild tasting fruits develop at the end of its branches.
'Ponderosa Lemon' a hybrid of Pomelo and Citron, with larger flowers blooming throughout the year, is often grown as an ornamental. The very large, yellow, bumpy fruit have a lemon's flavor and acidity and can be used in place of standard lemons. It is less cold hardy than a Lisbon lemon.
Wildlife: The flowers attract bees and other pollinating insects. The tree is a food plant for the Giant Swallowtail butterfly caterpillar – see Pests, below. Mammals may strip the bark off of young trees, consume fallen fruit, or climb the tree to eat the fruit.
Toxic / Danger: The fruit contain a family of chemical compounds called psoralens that are toxic to pets but not humans.
Origin: Asia.

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Cultivation and Uses

USDA hardiness zones: 9b-11. Flowers and young fruit are damaged at 29°F, nearly mature fruit is damaged below 28°F, the plant defoliates at 22-24°F, and there is wood damage at 20°F. It needs protection from wind.
Chill hours: None.
Heat tolerant: Yes.
Drought tolerant: Depends on rootstock. Drought will damage the crop.
Sun: Full sun with afternoon shade.
Planting: Place the tree in a sunny location, but with afternoon shade, away from the coldest part of the yard. Do not position the plant next to a frequently watered location, such as grass. Make sure there is enough space for the tree to grow to its full width and height, with clearance to walk around and where overhead lines will not be a problem.
The best time to plant a citrus tree is after the danger of frost is past, in late winter or early spring.
Plant the tree so that the root crown is at least one inch above ground level. The top roots must extend out from the trunk, just above, and uncovered by, soil.
Lemon trees can be grown in containers.
Soil: Well drained, native soil, pH 6.1-7.8 (slightly acidic to slightly alkaline), low in salt.
Fertilize: Citrus trees are heavy feeders. Apply an organic fertilizer every month from mid-February to early October. Apply a citrus micronutrient solution three times a year in February, May and August. Avoid NPK chemical fertilizers because they increase salt build-up in the soil. Do not fertilize after October to keep the plant from producing new growth that will be harmed by early frost.
Water after becoming established: Deep water or Basin irrigate, weekly in summer to monthly in winter, from the trunk to just beyond the canopy. The top of the soil should dry out between waterings. The water should reach 1-2' deep for newly planted trees and 3' deep for trees in the ground 3 years or more. Young trees need watering more often than older trees. A sign of insufficient water is leaves turning dull with inward curling edges.
Mulch: Apply organic mulch inside the drip line and 8" away from the trunk to reduce soil evaporation and reduce root zone heat and cold stress. Place a rodent gnaw guard around the trunk at the bottom.
Prune: Citrus trees are best grown as shrubs, so that leafy branches protect their entire trunk from direct sun. Only prune the lowest branches if their tips touch the ground. If you prune up from the bottom to expose the trunk, you must paint it with a tree trunk paint to avoid sunscald. Prune only after danger of the last freeze is over in late winter or early spring. Never prune in the summer.
Keep the soil under the drip line free of grass and other plants that can compete for water and nutrients.
Litter: Low.
Propagation: Cuttings grafted onto rootstock. Seed will not grow true and may be sterile.
Pests: Giant Swallowtail Butterfly caterpillar. This larvae resembles bird poop and has white and black and/or brown splotches. On a large plant it will cause no harm. On a small plant, relocate it to a large citrus. For other problems, see Citrus: Diseases and Disorders
Uses: Edible fruit, ornamental.



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Lemon: Citrus x limon meyer - flowers

Lemon: Citrus x limon meyer - fruit
Citrus x limon: 'Improved Meyer' flowers and fruit.


Lemon: Citrus limon - fruit
Citrus limon: 'Lisbon'.


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Latest update: March, 2020