Growing citrus plants in the PNW

You may not live in the subtropics, but you can still enjoy the wonderfully fragrant essence of citrus trees and shrubs inside your home (and outside in summertime). The sweetly scented blooms, colorful, edible fruit, and glossy leaves can brighten up almost any room with a touch of the sunnier climes. In fact, the modern greenhouse was developed primarily to grow citrus indoors for such cheery souls as Louis XIV, who had the first “orangerie” built at Versailles and demanded that his gardeners have orange trees in bloom at all times. But we won’t require that of you...

Here are some of the basics of Swanson’s citrus varieties and cultural requirements.

CITRUS VARIETIES

LIME Citrus aurantifolia — is a shrub or small tree, typically growing to 4-5 feet tall in a pot. Prolific white flowers are followed by green-yellow fruits.

LEMON Citrus limon — can bloom frequently if the conditions are ideal. It can be grown as a shrub or trained as a tree up to 4 feet tall. Swanson’s most popular variety is the ‘Meyer Improved’ lemon, which is virus-free and heavily produces 3-inch diameter yellow fruit.

CALAMONDIN ORANGE Citrus mitis — profusely bears white flowers and 1- inch diameter, bright orange fruit. The fruit is quite bitter, often used in making marmalade or as a substitute for lemon or lime, but typically the calamondin is grown as an ornamental plant.

CULTURAL REQUIREMENTS

LIGHT - Citrus plants require as much bright light as you can give them, such as a west- or south-facing window, especially over the winter months. They can be moved outdoors from May - September. Protect plants from hot afternoon sun when you first move them outside. Slowly move the plant into brighter spots over the first few weeks until the plant is acclimated to full sun. Note that watering needs will increase with increasing light levels.

TEMPERATURE - Citrus prefer temperatures of 70-75ºF during the day and 55-65ºF at night. They may tolerate temps as cold as 40º but may drop flower buds and fruit as a result. This also may occur for several weeks when citrus plants are brought indoors for the winter. Any significant change in temperature can cause flower and fruit drop.

WATER - Citrus use water at a faster rate during flower and fruit production. Check your soil before each watering. The top 2 inches of sandy soil should be dry, but not the entire pot. Then add water until you see it running out of the bottom of the pot. One quick method for testing soil moisture is to lift the pot slightly to check its weight — once you know how light the pot feels when it’s empty, and how heavy it feels right after watering. After a few waterings, you will know what “time to water” feels like. Be sure to empty any excess water from the bottom saucer. Citrus roots should not be sitting in water.

HUMIDITY - Citrus plants require humidity to grow their best and resist insect infestations. You can mist the foliage often with clean, tepid water and/or place the pot on a pebble tray — an oversize saucer filled with pebbles and saturated with water. The water adds humidity to the air surrounding the pot, but the pot sits above the water on the pebbles.

FERTILIZER - Iron, zinc, and magnesium deficiencies are fairly common with citrus. Apply an acid-loving houseplant fertilizer from March to October. Swanson’s recommends an organic all-purpose fertilizer. Read the fertilizer label instructions thoroughly.

PESTS - Signs of an insect infestation may include webbing, sticky leaves, or spots on leaves. At the first sign, contact one of Swanson’s indoor foliage staff, who can help diagnose the problem and suggest remedies. As mentioned above, increasing humidity and regularly washing or misting the foliage with tepid water will help prevent infestations.

Enjoy your citrus plant and let us know how else we can help you!