Tree · Rutaceae
Calamondin Orange
Citrus × microcarpa
A pot-sized citrus that carries fragrant blooms and sour orange fruit at the same time, all year on a sunny sill.
Full sun
Every 5–10 days
55–86°F · 13–30°C
USDA 10–11
Overview
The calamondin is the citrus most people can actually keep alive indoors. It is a compact hybrid, often read as a cross of kumquat and mandarin, and it earns its keep by flowering and fruiting at once. Set it in a bright window and you get fragrant white blooms and small sour oranges together, more or less around the calendar.
Outdoors in the warmth of zones 10 and 11 it grows into a small tree, but most gardeners keep it in a container and bring it under cover before frost. That portability is the whole appeal. The plant takes hard pruning in stride, so you can hold it to the size of your room and still pick fruit.
Do not expect a sweet eating orange. The fruit is bracingly tart, prized for marmalade, juice, and a squeeze over food rather than for snacking. Give the plant strong light, even moisture, and a steady citrus feed, and it rewards you with both scent and color.
Care
The short version: the brightest light you can give it, ideally full sun, with soil kept evenly moist in the growing months and drier in winter. Feed monthly from late winter into fall with a citrus fertilizer, and keep it in a warm, draft-free spot.
Light
Give a calamondin full sun wherever you can, which means the brightest window in the house, a south-facing one for choice. It gets by in bright indirect light or partial shade, but thin light costs you flowers and fruit.
Water
Keep the soil evenly moist through the growing season, letting the top inch or so dry between waterings, then ease off in winter. Settled plants handle a short dry spell, but let them parch and the fruit set falls away.
Soil
Plant in a rich, well-drained mix, a loose all-purpose potting blend in a container or a sandy to clay loam in the ground. A pH of 6.0 to 7.0 keeps the roots happy and the leaves green.
Temperature
It runs best from about 55°F to 86°F (13°C to 30°C) and wants no part of frost. Keep it clear of cold drafts and hot vents, both of which can trigger a sudden drop of leaves.
Humidity
Aim for 40% to 60% humidity, an easy range outdoors and in many homes. Dry winter air invites spider mites, so a humidifier or the odd misting earns its place when the heating is on.
Feeding
Feed monthly from about February to October with a balanced citrus fertilizer that includes micronutrients. The extra iron, zinc, and manganese are what keep the new leaves from yellowing on a heavy-feeding citrus.
Pruning
Prune lightly to shape the plant and to clear out dead, weak, or crossing wood. Rub off any suckers below the graft union, since they sap the plant, and trim freely to hold a container specimen compact.
Repotting
Move the plant into a larger pot every 2 to 3 years in spring, before the roots circle the inside or push out the drainage holes. Water rushing straight through or a plant that wilts fast is your cue it has outgrown its home.
Size & spacing
Grown out, it reaches 6 to 20 feet (1.8 to 6 m) tall with a spread of 6 to 10 feet (1.8 to 3 m), though a pot and regular pruning keep it far smaller. Give an in-ground tree room for that full spread so air can move through the canopy.
Troubleshooting
Most calamondin trouble shows up on the leaves, and most of it traces back to light, water, or a pest that slipped in. Read the early signs and you can fix the cause before the plant sheds its canopy. Match what you see below, then act.
Leaves yellow and drop soon after coming indoors for winter
A calamondin dislikes a sharp move from bright outdoor sun into a dim, warm room, and it answers with shock leaf drop in the first days or weeks. Set it in your brightest window, hold the temperature steady away from vents and drafts, and let the soil surface dry before each drink. Raise the humidity with a humidifier or a regular misting, and new growth follows once it settles in.
Fix:
- Place in the brightest available window (a sunny southern exposure)
- Keep temperatures stable and away from heat vents or cold drafts
- Mist or use a humidifier
- Let soil surface dry before watering
Pale or yellowing leaves with green veins
Yellow leaves on a citrus usually mean chlorosis from a hungry plant or sodden roots. Green veins on otherwise yellow new growth point to a micronutrient shortfall, while an all-over pale look points to a need for nitrogen. Feed with a balanced citrus fertilizer that carries micronutrients, fix any drainage trouble, and nudge the soil toward the slightly acidic side it prefers.
Fix:
- Apply a balanced citrus fertilizer containing micronutrients
- Improve drainage and avoid waterlogging
- Correct soil pH toward slightly acidic
Sticky leaves, black sooty film, or fine webbing
Sticky foliage and a black, sooty coating are the calling card of scale or mealybugs, sap-feeders that drip honeydew the mold then grows on. Fine webbing and stippled leaves instead point to spider mites, which thrive in dry indoor air. Wipe the pests off and treat with horticultural oil or insecticidal soap, raise the humidity to push back the mites, and keep the plant apart from your others until it is clean.
Fix:
- Wipe off pests and treat with horticultural oil or insecticidal soap
- Raise humidity to discourage spider mites
- Isolate the plant from other houseplants until controlled
Toxicity
The sour fruit is good to eat, but the rest of the plant is not pet friendly. The leaves, peel, and fruit carry essential oils and psoralens that upset an animal's stomach and can make skin touchy in sunlight. Keep pets and livestock away from the foliage and prunings, and wash your hands after you handle it.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds
Safe for
People
Cats Mild
A cat that chews the leaves or peel may drool, vomit, or get loose stools, and often turns quiet and off its food. The skin can also grow sensitive to sunlight after contact with the oils.
Dogs Mild
Expect an upset stomach with vomiting or diarrhea, plus a dip in energy, if a dog gnaws the foliage or fruit. The citrus oils can leave the skin prone to a sun rash as well.
Horses Mild
The oils and psoralens in the leaves and peel unsettle a horse's gut and can leave it dull and out of sorts. Keep clippings and dropped fruit out of the paddock.
Rabbits Caution
The same irritant citrus oils make the leaves and peel a poor idea for rabbits, so it is safest to keep them well away from the plant.
Livestock Caution
Goats, sheep, and cattle are likely to react to the foliage oils much as other animals do, so fence the plant off and bin any prunings rather than tossing them in reach.
Birds Caution
The essential oils in the leaves and peel are best treated as off limits for pet birds, even though a thin sliver of the ripe flesh is sometimes offered.
People Fruit safe
The sour ripe fruit is a kitchen favorite and safe for people to eat. Wash your hands after pruning, since the oils in the leaves and peel can irritate skin and make it touchy in the sun.
Leaves, peel, and fruit contain irritant citrus oils; wash hands after pruning or handling fruit and keep fallen leaves and peels away from pets.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
Only a couple of forms turn up in homes and garden centers, and they differ mostly in the look of the leaves.
Variegata (variegated calamondin)
Its leaves are streaked green and creamy white, and the young fruit wears green-and-white stripes that fade away as it ripens.
Standard calamondin
The plain glossy-green form is the one most people grow as an ornamental indoor citrus.
How to propagate
You can multiply a calamondin from cuttings or seed at home, though the quickest, most reliable plants come grafted from a nursery.
Stem cuttingsModerate
Late spring to summer · About 6 to 10 weeks to root
Take cuttings in late spring or summer, dip the cut ends in rooting hormone, and keep them warm and humid under cover. Given those conditions they root in about 6 to 10 weeks into plants identical to the parent.
SeedModerate
Spring · Several weeks to germinate; years to bear fruit
Sow fresh seed in spring and it sprouts within a few weeks. Calamondin seeds are often polyembryonic, so seedlings come fairly true to type, but they are slow growers that take years to bear their first fruit.
GraftingDemanding
Spring to summer · Several weeks for the union to take
Most nursery plants are grafted in spring or summer onto a vigorous rootstock, with the union knitting over several weeks. It is the hardest method to pull off at home, but it buys you faster growth and earlier fruit.
Myths
Calamondin fruit is poisonous to people.
The fruit is very sour but perfectly edible, and cooks turn it into marmalade, juice, and a sharp seasoning. It is acidic, not poisonous. The real caution is for pets, since the oils in the leaves and peel can irritate them.
Calamondin is a true orange species.
Despite the name, it is a hybrid, Citrus x microcarpa, usually read as a cross of kumquat and mandarin. It is not a true orange, which is part of why the fruit runs so tart.