Though it’s too cold in the Willamette Valley to grow lemons, limes, and oranges as orchard crops, it is possible to grow them outdoors in the summer, and then move them inside for winter protection. Here are a few tips to help you make the most of your citrus plants:
Plant your citrus in the smallest container it will comfortably fit in – just a little larger than the root system – using a well-drained soil mix (such as Gardner and Bloome Cactus Palm and Citrus mix). Repot only when really root-bound; the smaller pot will help keep your tree to a more manageable size as well as reduce the risk of root rot.
Water regularly, and don’t let them dry out completely. Let the soil get surface dry, to a depth of 1/2″ to 1″, then water thoroughly. Citrus should never sit in a saucer of water, so drain well. If your house has dry air in the winter – forced air, fireplaces, and wood stoves often cause this – put some rocks in your saucer, and allow some water to stay in the saucer but not wick up into the pot. Citrus like some humidity. While citrus prefer some gentle air movement over stagnant conditions, avoid siting near heat vents or outside doors.
Lighting is critical. A very bright exposed south window may provide enough, but in the Pacific Northwest you are likely to need to supplement. Provide a full-spectrum light for 10-12 hours a day.
Feed citrus all year round – they don’t really go dormant if kept at appropriate temperature and lighting. Granular, water soluble and liquid fertilizers can be used. Fertilizers labeled for citrus are great, or you may use a fertilizer that is relatively balanced, with a bit of emphasis on nitrogen. Make sure it also provides iron, or use an iron supplement. Liquid or soluble orchid or acid-loving fertilizers will work fine, citrus like somewhat acidic conditions.
Citrus will do best if you take them outside for the warm season – they like the fresh air, and most require insect pollination to set fruit. Move them out when nighttime temperatures are staying in the upper 40’s or low 50’s (late May, usually), and bring them back in for the winter before nightly lows drop below that point (early September).
Citrus are subject to a number of insect pests. Inspect regularly for mites, mealy bugs, scale insects, and aphids. You can significantly reduce pest risks by cleaning the leaves every month or so; rub them down gently with tepid water, or clean and polish them more thoroughly with leaf shine.