Lemon
Sources last read 14 September 2026.
Difficult One of the harder ones, and one of the reasons the diagnosis tool exists.
Also called bergamot, bergamot orange, Chinese dwarf lemon, dwarf lemon, lemandarin, mandarin lime, medicinal bergamot, Meyer lemon, Otaheita rangpur, Otaheite orange, Otaite orange, rangpur and rangpur lime.
Lemon is toxic
- Not assessed for cats. This plant is not on the ASPCA list. That is not a finding of safety: none of the sources read for this site gives an answer either way. Treat it as unknown.
- Not assessed for dogs. This plant is not on the ASPCA list. That is not a finding of safety: none of the sources read for this site gives an answer either way. Treat it as unknown.
- Toxic to people. Citrus bearing lemons or limes only: the fruit is a skin allergen and can harm skin exposed to sunlight. Use gloves and protective gear when handling it. RHS
What the sources say about its care
- Light
- Full sunRHS · read 13 September 2026
- Water
- Moist but well-drainedRHS · read 13 September 2026
- Humidity
No source read publishes a humidity figure for any plant on this site. What follows is general guidance for foliage plants.
ASHRAE recommends indoor relative humidity between 30% and 60% 30–60%Penn State Extension · read 13 September 2026- Temperature
How cold this tolerates, not what it prefers. No source read for this site publishes a preferred range for a plant indoors.
H2 — 1–5°C 1–5 °CRHS · read 13 September 2026- Soil
- Loam; pH Acid or NeutralRHS · read 13 September 2026
- Toxic to cats
- Not on the ASPCA list. That is not a finding of safety.ASPCA · read 13 September 2026
- Toxic to dogs
- Not on the ASPCA list. That is not a finding of safety.ASPCA · read 13 September 2026
- Harmful to people
- Citrus bearing lemons or limes only: the fruit is a skin allergen and can harm skin exposed to sunlight. Use gloves and protective gear when handling it.RHS · read 13 September 2026
How it usually goes wrong
- Bleached patches on the side facing the glass
On a lemon the scorch appears within a few days of a sunny spell or a move, and it does not spread afterward.
Glass concentrates what would be tolerable outdoors, because it holds the heat and removes the moving air that carried it away. Its source describes full sun.
Telling it apart: Whether it appeared after a move. Scorch follows a change in position within days.
RHSDiagnose spots on the leaves on this Lemon- Edges of the leaves brown while the middle stays sound
Leaves on the side of the lemon nearest a heater or vent brown at the edges while those on the far side stay clean.
Penn State Extension cites ASHRAE's recommended indoor range of 30% to 60% relative humidity; a heated room in winter drops below it. Air that dry pulls water from the leaf faster than the roots replace it, and the margins are furthest from the supply.
Telling it apart: Where the plant stands. Browning concentrated on the side facing a heater points at the air.
Penn State ExtensionLemon brown leaf tips and edges: causes- Soft yellow leaves low on the plant, soil still wet
A sour smell from the compost is common on a lemon, and the leaves deepest inside the canopy come away when pulled. The surface may look dry while everything beneath it is not.
Its source calls for soil that is moist but well-drained. Past that, water in the pot displaces the air the roots need, and damaged roots then fail to supply the leaves above them.
Telling it apart: Whether the compost has dried at all since the last watering. A pot that has not dried in a fortnight is answering the question on its own.
RHSLemon leaves turning yellow: causes
Not sure which it is? Ask the diagnosis questions for Lemon.
Routine care
- Watering
- In the growing season they need lots of water plus small, regular doses of nitrogen fertilizer to boost growth and fruit size.NC State Extension · read 13 September 2026While growing in spring and summer, water generously and mist every day. Use a citrus fertiliser all year round as directed by the manufacturer; give little water in winter.RHS · read 13 September 2026
- Feeding
- In the growing season they need lots of water and frequent light doses of nitrogen fertilizer to boost growth and fruit size.NC State Extension · read 13 September 2026Use a citrus fertiliser all year round, following the manufacturer’s directions; water sparingly in winter.RHS · read 13 September 2026
- Propagation
- Lemons are grown from seed.NC State Extension · read 13 September 2026In summer, root semi-ripe cuttings; in early spring, layer. Sow seed in spring at 16°C; the seedlings are not true to type.RHS · read 13 September 2026
- Pruning
- Little pruning is needed beyond keeping the shape.NC State Extension · read 13 September 2026Follow pruning group 1.RHS · read 13 September 2026
- Pests and diseases
- Glasshouse red spider mite, mealybugs and scale insects can attack it. Disease is uncommon.RHS · read 13 September 2026
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Photographs
About the plant
The lemon is a species of small evergreen tree in the Citrus genus of the flowering plant family Rutaceae. A true lemon is a hybrid of the citron and the bitter orange. Its origins are uncertain, but some evidence suggests lemons originated during the 1st millennium BC in what is now northeastern India. Some other citrus fruits are called lemon.
From Wikipedia, CC BY-SA 4.0 · read 13 September 2026
- Native range
- as a cultigen derived from artificial hybrids.World Checklist of Vascular Plants, June 2026 release, CC BY.Kew WCVP, filed as Citrus × limon · read 13 September 2026AsiaRHS · read 13 September 2026
- Climate
- subtropicalWorld Checklist of Vascular Plants, June 2026 release, CC BY.Kew WCVP, filed as Citrus × limon · read 13 September 2026
- Growth form
- treeWorld Checklist of Vascular Plants, June 2026 release, CC BY.Kew WCVP, filed as Citrus × limon · read 13 September 2026Tree; habit open, spreadingNC State Extension · read 13 September 2026Bushy (evergreen)RHS · read 13 September 2026
- Size
- Height 120–240 in; width 120–180 inNC State Extension · read 13 September 2026Height 2.5-4 metres; spread 1-1.5 metres after 10–20 yearsRHS · read 13 September 2026
- Flowering
- Flowers purple/lavender, red/burgundy, white; blooms in fall, spring, summer, winterNC State Extension · read 13 September 2026Flowers white in spring, summer and autumnRHS · read 13 September 2026
- Uses
What sources record people using this plant for. A traditional or medicinal use listed here is a record of use, not advice to eat it or treat anything with it.
Lemon juice (fresh, canned, concentrated, frozen, or dried to powder) goes mainly into lemonade, fizzy drinks and other beverages. It is also used in pies and tarts, to flavor cakes, cookies, icing, puddings, sherbet, hard candy and preserves, in pharmaceutical products, and in salad dressings. Lemon slices garnish fish or meat, or accompany iced or hot tea so they can be added to it. Oil from the peel is used in furniture polish, soaps, detergents and shampoos. Bergapten in the fruit goes into tanning lotions because it boosts skin pigmentation. Being dark green and lemon-scented, the leaves go into bouquets and wreaths. The fruit is edible.NC State Extension · read 13 September 2026
Common problems with Lemon
Other Citrus
Plants with similar care
Sources
- ASPCA · read 13 September 2026
- Kew WCVP · read 13 September 2026
- NC State Extension · read 13 September 2026
- Penn State Extension · read 13 September 2026
- RHS · read 13 September 2026
- Wikipedia · read 13 September 2026
What this does not cover
The figures above are what published sources say, not measurements of the plant in your room. They say nothing about your pot size, your water, the season, or how far from the glass the plant stands, and those decide more than any figure here does.
Humidity has no species figure because no source read for this site publishes one, and the only temperature published for this plant is a cold floor. The simulator fills those gaps with general figures for its kind of plant, marked as general and listed on how we read sources. Where a toxicity row says the plant was not assessed, that is the absence of a finding and not a finding of safety.
If something is already wrong, the diagnosis tool asks about the soil, the window and the watering, which is where the answer usually is.