As temperatures begin to cool and the days grow shorter, all citrus grown in cold climates need to be prepared to come indoors for the winter. This routine should be gradual to ensure the plant does not suffer shock from too quick a climate change.
The most important consideration when transitioning citrus indoors is watering. As the days shorten, the plant's growth rate slows considerably. This results in water needs that are much less than in spring and summer. Start paying close attention to how wet the soil is. Check by pressing your finger into the soil up to the second knuckle. This is the most accurate way to determine whether the soil is on the dry side. You want to check the soil just before watering.
The soil's moisture content will differ depending on the conditions your plant is exposed to, so it requires your attention and understanding of how it responds to watering. Water only when the soil is on the dry side.
Next, gradually move your plant from its summer location to a spot closer to the house where it will receive radiant heat, porches with good sun exposure, or outside walls adjacent to heated rooms with sunlight are good examples. Keep it in this location until nighttime temperatures fall into the mid- to high-30s. The longer the plant can stay outdoors while nighttime temperatures remain above 35 degrees, the better.
Then, choose an indoor location with ample sunlight exposure. Large, bright, south-to-southwest-facing windows usually work well. Keep in mind this may not be enough, and supplemental lighting could be required. When choosing indoor lighting for winter, avoid full-spectrum lights meant for promoting growth. This is contrary to what the plant is naturally doing at this time of year and can hinder acclimation and fruit ripening. Instead, look for LED lights designed for flowering and ripening fruit.
In addition, place your plant away from heat sources such as vents, heaters, or wood stoves. Dry indoor air creates another challenge for overwintering citrus. In severely dry conditions, humidifiers placed near your plants can help.
Feeding your plant before bringing it indoors is ideal. Use an organic, acid-based fertilizer as you begin adapting your plant to the move. Feed again about 30 days before moving it back outdoors.
It is okay to transplant your citrus into a desired container when you first receive it. A 16-inch pot is recommended for a #3 size plant. Once planted, do not repot your plant during winter. This almost always results in plant loss, and we never recommend it. If repotting is necessary, wait until late winter, early spring, or just as you transition the plant back outdoors.
Watch for insect problems, which often occur once the plant is indoors. Mites and scale are the two most common, and if caught early, they are easy to manage. Small black bugs emerging from the soil are usually fungus gnats, a clear sign of overwatering!
Lastly, yellowing leaves and discoloration are common when bringing plants indoors. The goal is to transition your plant indoors as healthy as possible. A plant brought in already showing discoloration will rarely recover until the following spring. If your plant is discolored when moving inside, follow the care instructions above and resume working on its health the next spring.
