Members of the Citrus family, lemons, according to genetic analysis, 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.
Form: 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: 3. Discard any small fruits started in the
first three years so the plant can put more energy into growth.
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 the 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.
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 scientific 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: Attracts bees, insects, birds, and 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
Toxic / Danger: Not to humans. Toxic to pets.
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.
Sun: Full sun.
Drought tolerant: Depends on rootstock. Drought will damage the crop.
Water after becoming established: Deeply, monthly in winter to weekly
in summer, from the trunk to just beyond the canopy. Lemon trees require 20% more water than orange trees
of the same size.
Young trees need watering more often than older trees even though older trees consume more water.
A sign of insufficient water is leaves turning dull and curling inward from the edges.
Soil: Well drained, native soil, pH 6.1-7.8
(slightly acidic to slightly alkaline), low in salt.
Fertilize: Do not fertilize the first two years.
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. Do not fertilize
after October to keep the plant from producing new growth that will be harmed by early frost.
Mulch: Use no more than 3" of aged compost under the canopy and
keep it one foot away from the trunk. Place a rodent gnaw guard around the trunk at the bottom.
Planting: Can be grown in containers.
Prune: Not necessary. If you prune up from the bottom to expose the trunk,
you must paint the trunk with a white tree trunk paint to avoid sunscald.
Propagation: Cuttings grafted onto rootstock. The seed is not likely
to grow true or may be sterile.
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. See
Citrus: Diseases and Disorders
Uses: Ornamental, edible fruit.
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