Growing Citrus Indoors

The Orangery display in the Hughes Conservatory features citrus trees. These plants can be a beautiful and bountiful addition to the home if provided with the right conditions. Use these tips to grow your own citrus tree in your Iowa home.

• Start with dwarf varieties. Meyer lemon, Ponderosa lemon, Persian lime, and calamondin oranges are good choices.
• Like most indoor plants, use a well-drained potting soil in a container with good drainage. Fertilizer requirements are similar to most houseplants as well.
• Light is important for flower and subsequent fruit development. Citrus will need 8-12 hours of bright sunlight every day, even in the dead of winter. Provide artificial light, if abundant natural light cannot be provided.
• Temperatures are best around 65°F. Avoid any temperature fluctuations from drafty doors or vents. This will lead to leaf, flower, and fruit drop.
• Providing adequate humidity for citrus indoors is difficult, especially in winter. Plants need at least 50% humidity to do well. Use a humidifier or pebble tray. Misting will clean the leaves, but will not alter the humidity in the air.
• All citrus will love a “summer vacation” on the deck or patio from late spring to early fall. Move outdoors when temperatures are above 55°F at night and bring back inside in the fall when temps cool down.
• When transitioning from indoors to out or visa versa, do it gradually. Any sudden changes in light levels or temperatures will result in leaf, flower and fruit drop. Ideally trees will be in part to nearly full sun when outside, but you cannot transition to those conditions instantly. Move them from low to high light gradually over several weeks.
• Watch plants carefully for scale. This very common pest on citrus will be difficult to eradicate if left to get out of control.
• If plants are exclusively indoors, you will need to use a small paint brush to pollinate the flowers. No pollination = no fruit!
• The fruit often take months to develop and ripen. Harvest only when ripe. Color is not a reliable way to tell ripeness. The fruit will be slightly soft when squeezed when fully ripe.

Prepared by Aaron Steil, Assistant Director