Tree · Rutaceae
Calamondin Orange
Citrus × microcarpa
A pot-friendly citrus that gives you sweet-scented blooms and tart little oranges at the same time, right on a sunny windowsill.
Full sun
Every 5–10 days
55–86°F · 13–30°C
USDA 10–11
Overview
If you have been nervous about growing citrus indoors, the calamondin is a kind place to begin, since it is the one most people really can keep happy on a windowsill. It is a small, forgiving hybrid, usually thought of as a kumquat crossed with a mandarin, and it has the charming habit of blooming and fruiting at the same time. Put it in a bright window and you get fragrant white flowers and little sour oranges together for much of the year.
Where it stays warm, in zones 10 and 11, it can settle into a small tree outdoors, but you will likely keep it in a pot and bring it inside before any frost. That easy portability is much of its charm. It also takes pruning kindly, so you can keep it to a size that suits your room and still gather fruit, and the odd snip will not hurt it.
Just do not expect a sweet orange to eat straight from the tree. The fruit is brightly tart, which is exactly why it shines in marmalade, juice, and a squeeze over a dish rather than as a snack. Give the plant good light, steady moisture, and a regular citrus feed, and it pays you back with both scent and color, mistakes and all.
Care
The short version: offer the brightest light you can, full sun if possible, keep the soil evenly moist while it is growing and a little drier in winter, feed it monthly from late winter through fall with a citrus fertilizer, and give it a warm, draft-free corner to call home.
Light
Give your calamondin as much full sun as you can, which usually means the brightest window you have, a south-facing one if there is a choice. It will get by in bright indirect light or partial shade, so do not panic in a darker home, but remember that thinner light means fewer flowers and less fruit.
Water
Keep the soil evenly moist while the plant is growing, letting the top inch or so dry out between drinks, then water less through winter. A settled plant forgives a short dry spell, so a missed watering is no disaster, but letting it bake dry will cost you fruit.
Soil
Plant it in a rich, well-drained mix, a loose all-purpose potting blend in a container or a sandy to clay loam in the ground. Aim for a pH of 6.0 to 7.0 and the roots stay content and the leaves stay green.
Temperature
It is happiest from about 55°F to 86°F (13°C to 30°C) and really does not like frost. Keep it away from cold drafts and hot vents alike, since a sudden chill or blast of heat can make it drop leaves, but a steady spot soon settles it.
Humidity
Aim for 40% to 60% humidity, which is comfortable both outdoors and in many homes, so this is rarely a worry. Dry winter air can tempt spider mites, so a humidifier or an occasional misting is a small kindness once the heating comes on.
Feeding
Feed monthly from about February to October with a balanced citrus fertilizer that includes micronutrients. That little extra iron, zinc, and manganese is what keeps the fresh leaves from yellowing on a citrus that likes to eat well.
Pruning
Prune lightly to shape the plant and to take out any dead, weak, or crossing wood, and do not be shy about it. Gently rub off any suckers below the graft union, since they draw strength away, and trim as freely as you like to keep a container plant nicely compact.
Repotting
Move it into a bigger pot every 2 to 3 years in spring, before the roots start circling inside or poking through the drainage holes. If water suddenly rushes straight through or the plant wilts quickly, that is its quiet way of telling you it has outgrown its home.
Size & spacing
Left to grow, it can reach 6 to 20 feet (1.8 to 6 m) tall and spread 6 to 10 feet (1.8 to 3 m), though a pot and a little regular pruning keep it far more manageable. If you plant one in the ground, give it room for that full spread so air can drift through the canopy.
Troubleshooting
Almost everything that troubles a calamondin shows up first on the leaves, and most of it comes down to light, water, or a pest that wandered in. The good news is that catching those early signs lets you fix the cause long before the plant loses its leaves. Find what matches your plant below, then take it one gentle step at a time.
A flush of leaves yellows and falls just after the move indoors
Try not to worry if your calamondin sheds leaves in its first days or weeks inside, because this is shock leaf drop and most plants pull through it. The jump from bright outdoor sun to a dim, warm room is simply a lot to adjust to all at once. Settle it in your sunniest window, hold the warmth even and away from vents or drafts, let the soil top dry before you water, lift the humidity with a humidifier or a gentle misting, and fresh growth comes back as it finds its feet.
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
Leaves turn pale while the veins stay green
Pale leaves on a citrus are a gentle signal of chlorosis, which usually means the plant is hungry or its roots are sitting too wet, and both are easy to put right. When new leaves go yellow but their veins stay green, that points to a shortage of trace nutrients, while a soft all-over paleness asks for more nitrogen. Offer a balanced citrus feed that carries micronutrients, ease up any soggy drainage, and tip the soil toward the slightly acidic side it loves, and the green returns.
Fix:
- Apply a balanced citrus fertilizer containing micronutrients
- Improve drainage and avoid waterlogging
- Correct soil pH toward slightly acidic
Sticky leaves, a black film, or fine webbing show up
Sticky leaves topped with a black, sooty film are the friendly warning sign of scale or mealybugs, sap-sippers whose sweet honeydew lets the mold settle in. If you spot fine webbing and faint speckling instead, spider mites are the culprits, and they love dry indoor air. None of this is the end for your plant: wipe the pests away, treat with horticultural oil or insecticidal soap, raise the humidity to send the mites packing, and keep it on its own until it is clean again.
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 lovely to eat, yet the rest of the plant is not meant for animals. Its leaves, peel, and fruit hold essential oils and psoralens that can unsettle a pet's stomach and leave skin a little sun-sensitive. Keep pets and livestock away from the foliage and the prunings, and give your hands a wash after you have handled it, and everyone stays comfortable.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds
Safe for
People
Cats Mild
If a curious cat nibbles the leaves or peel, it may drool, be sick, or have loose stools, and it often goes quiet and loses interest in food for a while. Its skin can turn sensitive to sunlight too after the oils touch it, so a little extra care helps.
Dogs Mild
A dog that chews the foliage or fruit tends to get a queasy stomach with vomiting or diarrhea and a dip in its usual energy. The citrus oils can also leave the skin prone to a sun rash, so keep an eye on it and it should settle.
Horses Mild
The oils and psoralens in the leaves and peel can upset a horse's gut and leave it looking dull and a bit off. Clearing clippings and any dropped fruit out of the paddock keeps everyone comfortable.
Rabbits Caution
Those same irritant citrus oils make the leaves and peel a poor choice for rabbits, so the kindest thing is to keep them happily out of reach of the plant.
Livestock Caution
Goats, sheep, and cattle will likely react to the foliage oils the way other animals do, so a simple fence and a habit of binning the prunings rather than leaving them around keeps the herd safe.
Birds Caution
It is best to treat the essential oils in the leaves and peel as off limits for pet birds, even though a thin sliver of the ripe flesh is sometimes shared as a treat.
People Fruit safe
Good news for the cook: the sour ripe fruit is safe and welcome to eat. Just wash your hands after pruning, since the oils in the leaves and peel can irritate skin and leave 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 tend to find their way into homes and garden centers, and the main difference between them is simply the look of the leaves.
Variegata (variegated calamondin)
You will know this one by leaves brushed with green and creamy white, and by young fruit that wears green-and-white stripes which quietly fade as it ripens.
Standard calamondin
This is the simple glossy-green plant that most people happily grow as an ornamental indoor citrus.
How to propagate
There are a few friendly ways to grow more calamondins at home, from cuttings to seed, though the quickest and most dependable plants usually arrive grafted from a nursery.
Stem cuttingsModerate
Late spring to summer · About 6 to 10 weeks to root
Cuttings are a lovely place to start: take them in late spring or summer, dip the cut ends in rooting hormone, and tuck them somewhere warm and humid under cover. Looked after that way they put down roots in about 6 to 10 weeks and grow into plants just like the parent.
SeedModerate
Spring · Several weeks to germinate; years to bear fruit
Sowing fresh seed in spring is easy, and sprouts appear within a few weeks. Because calamondin seeds are often polyembryonic, the seedlings tend to come fairly true to the parent, though they are slow and patient and take years before their first fruit.
GraftingDemanding
Spring to summer · Several weeks for the union to take
Most nursery plants come grafted in spring or summer onto a sturdy rootstock, and the join knits together over several weeks. It is the trickiest method to manage at home, so do not feel you must master it, but it does give faster growth and earlier fruit.
Myths
The fruit of a calamondin is poisonous to people.
Rest easy on this one, because the fruit is wonderfully sour yet completely edible, and cooks turn it into marmalade, juice, and a bright seasoning. It is tart and acidic, never poisonous. The care you do owe is to your pets, since the oils in the leaves and peel can bother them.
A calamondin is a true species of orange.
The name is a little misleading, since this is a hybrid, Citrus x microcarpa, usually understood as a kumquat crossed with a mandarin. It is not a true orange at all, and that mixed parentage is much of why the fruit tastes so sharp.