Episode Details

Growing Citrus Trees Indoors

Here in California, or if you live in Arizona or Texas or Florida, you get to grow citrus in your backyard, year round. For most of the rest of the nation, though, that would be a challenge. A challenge to the point where maybe you have to bring it indoors for the winter. That could even be true here in California if you’re growing a citrus variety, such as lime trees, that can lose their fruit when the thermometer drops to 32 degrees, which happens here in the Central Valley on a regular basis. Maybe you have a really nice greenhouse to grow citrus. Combined with a heater to keep temperatures above 40, that would be ideal.

When it comes to tips for growing citrus, we turn to Lance Walheim, who has written several books about citrus. His titles include, “Citrus The Complete Guide to Selecting and Growing More Than 100 Varieties," and “All About Citrus and Other Subtropical Fruits.” He also was one of the contributing editors to the Sunset Western garden book that has a very good citrus section.

Walheim says indoor citrus growers need to choose the right varieties to be successful.

“I have met many people who have been growing  Meyer lemons and kumquats back East in very cold climates for 30-40 years, so people can be successful about it,” says Walheim. “But make sure you choose the right variety. I think you need to try growing citrus that is highly acidic. One of the best ones is the Meyer lemon tree. It's a very precocious tree that loves to bloom, and doesn't need a lot of heat to ripen. And it's a small tree so it can grows perfectly well in a container. All the kumquat hybrids, including Calamondins, are perfect for indoors. Also, they have smaller fruit that ripens quicker. And again, they have a propensity to rebloom often.” And despite the reputation of lime trees being very cold sensitive, Walheim says one lime variety, in particular, makes for a good household specimen. “Bearss lime is a good variety to try indoors,” says Walheim.

And what about the option of letting your citrus trees enjoy the warmer months outdoors and bringing them indoors for the winter? Is that viable? “It certainly is,” exclaims Walheim. “The key thing is to provide a transition zone, if moving it back and forth. When you're moving a citrus tree from indoors to outside in the late winter or early spring, or  from the outside to the indoor conditions in November or December in the Central Valley (or earlier in colder climates), you're really changing things for that tree. The humidity levels outside could be over 50-60%. You take it inside where the house is heated, you're dropping down to 10% humidity. So those are dramatic changes, and they're going to affect the tree as will the changing light conditions. So what I really recommend, whether you're going inside or outside as you provide a transition period, is to do it gradually.”

The process involves moving that tree every day for awhile, so make sure the plant is in a container that isn’t too big for you to move, perhaps 15 to 20 inches across at the top. Better yet, mount the container on a heavy duty small furniture dolly to roll the plant inside and out.

“If you're taking the tree outside, make sure it is in a shady spot during this transition period,  it may take several weeks,” says Walheim. Give them a shady condition several hours a day, and then move them back inside for the night. Move them to more outside light gradually.”

Walheim says the more critical transition is moving a containerized citrus tree to the indoors for the winter in colder climates. “You certainly don't want them next to a heater vent, you want to do whatever you can