Garden Variety: Growing citrus fruits inside requires ideal conditions
Homegrown lemons are a rarity in Kansas, but committed gardeners can succeed at growing them and other citrus fruit by creating the right environment. Newer, improved dwarf varieties are the best bet for indoor growing of citrus. Gardeners with sunrooms and greenhouses may opt for larger varieties while still giving consideration to varietal differences given the specific conditions.
Improved Meyer lemons are the most common and well-known variety of citrus fruit successfully grown by Kansas gardeners. Meyer lemons are a cross between lemons and either a mandarin or an orange, so they are a little sweeter than regular lemons. The “Improved” variety is virus-resistant.
Mexican limes or key limes are also popular options for indoor citrus. These limes are smaller and more acidic than the Persian limes typically sold in stores. They are still good for all of the same things as other limes, and are pretty delicious in pie. Mexican limes are yellow when ripe and are about the size of a ping-pong ball.
Another option that can be grown indoors is calamondin. Calamondin produces a small orange fruit that is believed to be a natural hybrid of kumquat. Calamondin are slightly larger than Mexican limes. The trees are widely planted for their ornamental value in California and Florida. Fruit and juice from calamondins are used similarly to lemons and limes.
The amount of light the plant will receive is key to success in growing citrus fruit indoors. Lemon trees and other citrus are tropical plants that need 8 to 12 hours of direct sunlight per day to thrive. Supplemental lighting is an option if adequate light is unavailable otherwise.
Citrus fruit can also be grown outdoors in summer months and brought inside for the winter. They can survive slightly reduced light for a few months, but a south or southwest window, or grow lights is still best for the indoor months. If practicing this method, remember to acclimate the plant each season. In the spring, move it to a shady area for few days, then gradually increase the amount of direct sunlight. In fall, reduce the amount of sunlight by moving it into the shade before moving it indoors.
Watering practices are the next thing to consider. Citrus fruit cannot tolerate a condition known as wet feet, when water holds in the bottom of a pot and surrounds the ends of the roots growing there. The extra water essentially suffocates the roots and makes a more favorable environment for certain disease pathogens.
When watering, set the plant in a sink or bathtub and water until soil is completely moistened and water drains from the bottom. Potting soil is like a sponge and can be hard to re-wet when completely dry. It also holds water to a point of saturation. Allow the soil to almost completely dry out before watering again, which may be a week or more. Check the soil below the surface before watering as the top layer dries the quickest.
To re-pot citrus, use a container only slightly larger than what was used before and make sure it has drainage holes. Use an extra well-drained potting soil mix. Some are even labeled for citrus fruit, although soil labeled for cacti and succulents may also provide adequate drainage. If keeping the plant in the same size pot is desirable, loosen soil and shave off a small portion of the roots to allow the plant to go back into the pot with a little fresh potting soil.
Citrus fruit plants grow best between 55 and 85 degrees Fahrenheit. They can survive brief exposures to higher and lower temperatures, allowing them to survive Kansas summers outdoors.
In a sunroom or greenhouse, use shade cloth in summer if necessary to keep plants from cooking. Provide supplemental lighting in winter if necessary in addition to heat.
— Jennifer Smith is a former horticulture extension agent for K-State Research and Extension and horticulturist for Lawrence Parks and Recreation.