Meyer lemon tree care: sun, water and winter

Light

Light is the limiting factor indoors. Clemson asks for at least 8 hours of sunlight, outdoors in full sun or indoors at a south-facing window with lots of bright natural light. The Illinois Extension puts citrus in its direct light category, about 1,500 foot-candles, which indoors means right in front of a south window and nowhere else. A few feet back, or behind a sheer curtain, the tree survives but rarely blooms.

Summer outdoors is the easiest way to build up the energy for flowers and fruit. When nights are reliably mild, move the pot out gradually, a few hours a day at first, because leaves grown indoors scorch in sudden full sun; the RHS calls this hardening off. In fall, bring it back before nights turn cold and give it the brightest room you have. A sunroom is ideal, Clemson says.

Water

Clemson's rule is to check the top 2 to 3 inches of soil for moisture before watering, and to aim for a root ball that never dries out completely but is never saturated for long either. A Meyer in a terracotta or plastic pot outdoors in July can need water almost daily in hot, dry spells, so check every morning. Water until it runs from the drainage holes and never leave the pot sitting in a full saucer.

Winter turns the risk around. The RHS lets the surface of the compost partly dry out before watering indoors, then waters thoroughly with tepid rainwater and lets the excess drain away. It names winter overwatering as one of the commonest problems with potted citrus and lists yellowing and shedding leaves as the warning signs. Err on the dry side from November to March.

Water quality matters more for citrus than for most houseplants. Clemson recommends rainwater where possible because it tends to have a lower pH than municipal supplies, which helps keep the mix in the slightly acidic range citrus prefer.

Soil and pH

Use a coarse, fast-draining mix. Clemson suggests a homemade blend of 4 parts shredded aged pine bark to 1 part peat moss or coir; if you use coir, it recommends agricultural gypsum to replace the sodium it carries. The RHS uses a specially formulated citrus compost, or a loam-based compost such as John Innes No 2 or No 3 with about 20 percent sharp sand mixed in. Never use garden soil in the pot.

Clemson gives the target pH as 5.5 to 6.5. Acidic water-soluble fertilizers and occasional Epsom salt help hold it there. Plant at the same depth as before, with the root flare above the soil line; Clemson notes that burying the flare invites crown rot.

Humidity

Clemson lists 30 to 60 percent humidity for optimum growth, and suggests a humidifier or a pebble tray near the tree in winter. The RHS goes further, saying humidity is particularly important when citrus are kept in heated rooms, and recommends standing the pot on a tray of gravel kept wet just below the surface, plus early-morning misting in summer. Dry air is one of the triggers it names for leaf drop and failed flowering.

Temperature

Clemson puts optimum temperatures for fruiting between 65 and 85°F (18 and 29°C) and says most citrus tolerate cooler spells down to around 50°F (10°C). For the winter months indoors, it recommends a room with southern exposure held between 55 and 65°F (13 and 18°C). The RHS adds that some lemons cope with as low as 42°F (5°C), and UF/IFAS describes the Meyer as handling cold better than other citrus, needing protection below 20°F (-7°C) in the ground. A potted tree is more exposed than one in the soil, so bring it in well before frost.

The cool winter room is not only about survival. Clemson explains that citrus usually flower in mid to late spring after a rest period below 68°F (20°C), and the RHS names cool or fluctuating temperatures and cold drafts as reasons a tree fails to flower or drops leaves. Steady and cool, but never freezing, is the target.

Fertilizer

Containers lose nutrients every time you water. Clemson recommends a slow-release citrus fertilizer such as 12-6-6 or 12-4-6, applied 2 to 3 times through the growing season depending on the product's release rate, with an acidic water-soluble feed as a supplement. Most soluble fertilizers lack calcium and magnesium, so Clemson suggests Epsom salt or gypsum when a soilless media test shows a shortage. The RHS treats citrus as hungry plants that benefit from feeding all year: a high-nitrogen summer citrus feed from late March to October, then a balanced winter citrus feed from November to mid-March. UF/IFAS suggests a 6-6-6-2 mix with magnesium for Meyer lemons in the ground.

Work out the dose for your watering can with the fertilizer dilution calculator →

Repotting

The RHS says a newly bought citrus can usually stay in its original pot for several years and warns that overpotting into a much bigger container causes problems. Move it up once roots appear through the holes in the base, in spring, to a pot only slightly larger. Clemson's rule is a container about 2 inches wider and a new pot every three to five years, with a final pot that may be 18 to 36 inches across. Lightweight plastic beats heavy terracotta or concrete if you plan to move the tree twice a year; Clemson suggests a plant dolly for big ones. In the years between, topdress with fresh compost, as the RHS recommends.

• Roots appear through the holes in the base of the pot
• The pot dries out within hours on a warm day
• The tree has become top-heavy for its container

Propagation

The RHS calls semi-ripe cuttings the easiest way to propagate citrus, because the new plants are clones and produce the same quality of fruit, usually within a few years. Take them in summer from firm current-season shoots. Growing from a supermarket seed is not worth it: the RHS notes seedlings take years to fruit, the fruit may be inferior, and seeds can carry disease. Clemson adds that Citrus cannot be sold or shipped outside three South Carolina counties under the citrus greening quarantine, so buy certified nursery stock, as UF/IFAS also advises.

Methods: Semi-ripe cuttings · Best season: summer.

Common problems

Leaf drop is the signature complaint, and it has several causes: winter overwatering, cold drafts, dry heated air and shortage of nutrients, all named by the RHS. Root rots from Pythium or Phytophthora, which Clemson describes in poorly drained media, show as wilting with wet soil. Sap feeders are the main pests indoors: scale, aphids, whiteflies, mealybugs and spider mites, with sooty mold growing on their honeydew. The RHS recommends limiting a tree about 3 feet tall to 20 fruits at a time so it does not exhaust itself.

Not sure which one it is? Try the plant problem diagnosis tool →

Is the Meyer lemon tree toxic to cats and dogs?

The ASPCA lists lemon and orange, the two parents of the Meyer lemon, as toxic to cats and dogs. Both entries name essential oils and psoralens as the toxic principles and list vomiting, diarrhea, depression and possible dermatitis as clinical signs. The ASPCA notes that the fruit is edible but that the skins and plant material can cause problems, so the risk is a pet chewing leaves, stems or peel rather than a lick of juice. Keep fallen fruit and pruned branches out of reach, and call your veterinarian or the ASPCA Animal Poison Control Center if a pet eats some.

Check any other plant against the ASPCA lists →