By moving container-grown citrus into a greenhouse, sunroom, or bright indoor location for the winter, gardeners anywhere can grow them. If you hope to harvest fruit, choose a naturally acidic citrus, not a sweet orange or grapefruit. Examples of acidic varieties include lemons, limes, calamondins, and kumquats. These are most likely to produce fruit indoors in winter. Other types of citrus will grow and flower but are less likely to hold fruit to maturity.

Calamondins are an attractive, compact citrus suitable for indoor growing.

To grow your citrus as a houseplant, you'll want to give it as much light as possible. This can be done by placing it in a sunny window or by setting it under grow lights or shop lights fitted with one cool and one warm bulb. They are happiest in temperatures between 50-80°F.

Proper watering is one of the keys to growing any citrus plant. The aim is to keep the soil moist but not wet. Stick your finger into the soil, at least up to the second knuckle. If you feel dampness at your fingertip, wait to water. If it feels dry, water your plant until you see it run out of the bottom of the pot.

If using slow-release/controlled-release fertilizers, apply in January or February to enhance the spring bloom, May or June to encourage good fruit set, and again in fall (September/October) to keep the plant fed through the winter. If you’re fertilizing with liquid fertilizer, you should take a break during the winter if your citrus is not producing new growth. Resume fertilizing in February.

Citrus fruit can take up to a year to ripen. Because citrus fruit will only continue to ripen while it is still on the tree, make sure to wait until it's ripe before picking. Use a knife or scissors to cut off the fruit so you don't risk damaging the plant by pulling off a larger piece than intended.

Interesting fact: Citrus are unusual in that they can have buds, flowers, developing fruit, and mature fruit present at the same time.

Holding Citrus dormant: If you just don’t have the light or space to keep citrus looking good in the winter, you can force the plant into dormancy and keep it in a cool basement or a lightly heated garage.

First, prune to a manageable size if needed. Force the plant into dormancy by keeping it cool and dark. Shoot for a temperature of about 40-45 degrees. Warmer temperatures will encourage growth. Periods of cooler temperatures are OK, but don’t let it freeze.

Reduce water until some leaves drop. Water only when the top 2-3” of soil is dry, with just a bit of water (not enough to run through). If stems begin to shrivel you’re not using quite enough water. Do not fertilize at all during this period.

In spring repot and prune to shape if necessary. Move outdoors once evening temperatures remain in the 40s. Feed with ½ strength fertilizer until leaves start to develop, then feed normally

Winter Care for Citrus