Indoor citrus such as Meyer lemon, calamondin, and kumquat often flower in late winter, but without bees the flowers need help: dab pollen from the yellow anthers onto the sticky center of each open flower with a soft brush for two or three mornings in a row. Then keep the tree in the brightest light you have, with cool nights around 55 to 65°F, steady moisture, and regular citrus feed, and expect some small fruit to drop. The fruit that stays usually takes six months or more to ripen.
Most indoor citrus are self fertile, so one tree can set fruit on its own. The problem indoors is that nothing moves the pollen. A brush does the job of the bees, and good light and steady care do the rest.
Why indoor citrus flowers and then drops them
A tree that blooms heavily and sets nothing usually has one of four issues:
- No pollination. Flowers that are never pollinated fall off within a week or two.
- Too little light. A tree in a dim spot cannot support many fruits and sheds them.
- Dry roots or swings in watering. A pot that dries out completely, then gets soaked, often triggers flower and fruit drop.
- Hot, dry air. Flowers fade fast near heat vents, and low humidity can make the sticky stigma dry out before pollen lands.
Fixing pollination and light handles most cases. For moving a tree indoors in the first place, and the leaf drop that often follows, see moving citrus and tropicals indoors for winter.
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Find My Plants →How to hand pollinate citrus flowers
- Work in the morning when flowers have just opened and pollen is fresh.
- Use a soft, small, round artist's brush (about size 2 to 4) or a cotton swab.
- Collect pollen by gently twirling the brush against the yellow anthers around the center of a flower.
- Touch the brush to the stigma, the sticky knob at the tip of the central stalk, until you see yellow grains on it.
- Move flower to flower, and repeat on the same flowers for two or three mornings.
A small green swelling at the base of the flower within two weeks means fruit has set. Some gardeners also hold the back of a vibrating electric toothbrush against the flower stem to shake pollen loose, which works well on trees with many small flowers.
Shop pollination and feeding supplies on Amazon
Soft round brushes for moving pollen, a fertilizer made for fruiting container trees, and a thermometer hygrometer to track the room. We may earn a commission at no extra cost to you.
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Light, temperature, and humidity
Light is the biggest factor. Give the tree a south or west window, as close to the glass as you can without leaves touching cold panes. Where days are short or windows are shaded, add a full spectrum grow light for 12 to 14 hours a day. See grow light basics for winter houseplants.
Citrus flower and set fruit best with days around 65 to 75°F and nights about 10 degrees cooler. Keep the tree away from heat vents and radiators, which dry flowers and leaves. A humidifier or pebble tray nearby helps flowers stay open longer and keeps spider mites down.
Water and feeding while fruit sets
Water when the top 1 to 2 inches of mix feel dry, then water thoroughly until a little drains out, and empty the saucer. A soil moisture meter takes the guesswork out of large pots. See soil moisture meters for houseplants.
Feed with a fertilizer made for citrus, which includes extra nitrogen plus micronutrients such as iron, magnesium, and zinc, following the label for container trees. Pale or yellow leaves with green veins often point to a micronutrient shortage, especially iron or magnesium.
Shop light, water, and moving gear on Amazon
A full spectrum grow light for short days, a cool mist humidifier, a soil moisture meter, and a rolling caddy for heavy pots. We may earn a commission at no extra cost to you.
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Thin the fruit for better lemons
A small tree cannot carry every fruit it sets. Some natural drop of pea size fruit is normal. If many fruits remain on a young tree, thin clusters to one or two fruits and remove extras close to the branch tips. Fewer fruits grow larger and the tree keeps its strength. Meyer lemons and calamondins may need six to nine months to ripen; harvest when the fruit is fully colored and gives slightly to a gentle squeeze.
Pests on flowering citrus
Check the undersides of leaves and the stems for scale and mealybugs, which leave sticky honeydew, and for spider mites in dry heat. Treat early with a gentle soap or horticultural oil spray labeled for citrus, out of direct sun. See mealybugs and scale on houseplants and spider mites in dry winter heat.
Safety notes
Many citrus have sharp thorns, so wear gloves when you prune or thin fruit, and use clean, sharp pruners. A large potted tree is heavy; move it on a rolling caddy instead of lifting it, and get help on stairs.
Pet notes
Citrus trees are toxic to pets. The ASPCA lists lemon, lime, orange, and grapefruit as toxic to dogs, cats, and horses. The leaves, stems, and peel contain essential oils and psoralens that can cause vomiting, diarrhea, depression, and skin sensitivity to light. Pick up fallen fruit and leaves, and keep the tree where pets cannot chew it. If a pet chews a citrus tree and seems unwell, call your veterinarian or the ASPCA Animal Poison Control Center at (888) 426-4435. See plants toxic to cats and plants toxic to dogs.
Bottom line
Brush pollen onto each open flower for a few mornings, give the tree the brightest spot you have with cool nights, water evenly, feed with citrus fertilizer, and thin heavy clusters. That routine turns a fragrant indoor bloom into fruit you can actually pick.
Related reading
- Moving citrus and tropicals indoors for winter
- Grow light basics for winter houseplants
- Mealybugs and scale on houseplants
- Rolling plant caddies for heavy pots
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