Botanical Name: Citrus aurantifolia
If you have a sunny spot for it, Key Lime Tree makes an easy house plant that will bear flowers and fruit off and on year-round.
Glossy, oval leaves growing on spiny stems are typically accompanied by white, star-shaped flowers. Those flowers are followed by 2-3 in (5-7.5 cm) round, green limes. Key lime fruit is smaller than the more common Persian lime (Citrus x latifolia). Key limes are also more acidic and tart, best known as the flavoring in Key Lime Pie.
Given enough light, you can expect flowers and fruit on the tree at the same time, making this citrus tree a delightful, fragrant house plant.
Got blooms, but no fruit? It probably needs pollinated. Fruit trees grown outdoors are pollinated from the wind or insects that carry the pollen from flower to flower. If you've kept your key lime tree indoors, it needs some help from you. Don't worry -- it's easy to do. To pollinate your dwarf citrus tree, use a small paintbrush to dab the stamens in the center of the flowers, moving from flower to flower to spread the pollen around.
Prune your plant. Pruning lime trees will keep them shapely -- and compact. You'll also encourage more flower buds to form. Prune in spring, removing old wood and long side branches. Once you get in the habit of yearly pruning, it's hardly any work at all.
Repot in spring. Repot only when the roots have filled the pot. Move to a pot only 1 size larger. Use a pot with a drainage hole to prevent overwatering, which can cause root rot.
Origin: Southeast Asia
Height: 3-5 ft (90cm - 1.5m)
Light: Plants that don't bloom aren't getting enough light. Put your lime citrus tree where it will get bright light with at least 6 hours of direct sunlight every day. Moving your lime tree outdoors to the patio for the summer is ideal. Just be sure to bring it back indoors if the temperature dips to 50°F/10°C at night.
Water: Keep soil evenly moist, but not soggy. Constantly wet soil may cause root rot. Water thoroughly to wet all the roots, then allow the top 2 inches (5 cm) to dry out before watering again.
Humidity: Aim to maintain 40% relative humidity or higher. If indoor air is dry, use a cool-mist room humidifier.
Temperature: Normal room 65-75°F/19-24°C. If you move your key lime tree outdoors for the warm months, don't worry -- it can take the heat. Just bring it back inside when the nighttime temperature drops to 50°F/10°C. This tropical citrus plant doesn't like the cold and won't tolerate frost.
Soil: Good-quality potting mix
Fertilizer: Feed every 2 weeks spring through fall. I highly recommend organic citrus tree fertilizer. It contains all the nutrients citrus trees need for healthy root growth and promotes flowers and fruits.
Propagation: Take 4 in (10 cm) stem tip cuttings in early summer. Dip cut ends in rooting powder, then insert them into moist potting mix. Enclose the cutting and container in a plastic bag or cover with a glass cloche to maintain high humidity. Cuttings should root in about 6-8 weeks.
Seeds taken from lime fruits will grow, but are unlikely to produce fruit.