Lime trees such as the Kaffir variety are good indoor citrus plants. If you are willing to hand pollinate the tree you can get a fruit harvest from them. Indoor lime trees do take more care and maintenance to keep healthy. There are a few things you can do to have a long lasting indoor lime tree.
Plant the lime tree sapling in a 5-gallon pot or bigger. Use lightweight potting soil mixed with perlite. Use indoor potting soil and an organic fertilizer or mulch combination to place minerals and nutrients in the soil. Use highly acidic fertilizer during June through August when the tree is growing; use a 20-10-10 fertilizer as a compliment to each watering. Pack the soil well around the root ball to avoid air pockets which can kill an indoor lime tree. Yearly applications of cottonseed meal or compost is recommended by Pleasant Valley Farm and Garden Supply in Grass Valley California; they also recommend applying the compost in late winter to early spring for best results. Check the soil for nitrogen levels occasionally because indoor citrus plants loose nitrogen due to watering; replace nitrogen into the soil as needed.
Lots of Sun
Put your indoor lime tree in a location where it can get plenty of sun. Lime trees like full sun to grow properly. Keep the plant in a window or patio with a south facing angle; this ensures that the indoor lime tree gets the maximum amount of direct sunlight during the day. Use windows that are away from trees or shrubs as these could shade the window causing the lime tree to loose valuable sunlight. Keep the median temperature around 60 degrees year-long. Sue Williams, an Adams County Master Gardener, says to use 40-watt grow lights suspended above the lime tree to supplement lack of sunlight during winter and overcast days.
Pruning and Maintenance Essentials
Picking the leaves every few weeks will help encourage growth. Keeping branches pruned back will keep the lime tree manageable and healthy. Indoor lime trees will likely not produce fruit unless you hand pollinate the tree.
Proper Watering Ensures Success
Water the indoor lime tree every few days and at least weekly. Make sure the container has proper drainage. Use containers with many small holes in the bottom. Use a layer of gravel at the bottom of the container to help the soil drain. Avoid over watering because standing water can kill lime trees. Heavy watering can result in waterlogged soil, bringing root rot and fungal infections. According to Colorado State University Extension, common problems from over watering can include yellowing of leaves and dropping foliage.
Watch for Pests
Be very observant for pests with indoor lime trees recommends the Colorado State University Extension service. Since pests such as aphids, mites, scale and mealybugs don't have natural predators indoors as they would in nature, these insects can overwhelm the tree quickly. The extension service also says you can help keep the tree insect free by not over watering, using containers with good drainage and increased salinity, and maintaining levels of nutrients. Some recommendations for infected trees from the CSU Extension include rinsing the tree outside with a garden hose or indoors in a shower using an insecticidal soap solution. Let the soap dry for several days before rinsing it off for best effect. If you find a severe infestation, compost the tree and clean the space thoroughly to remove all of the insects; then quarantine the room for a while.