Local lemons can be hard to come by unless you live in an area with a year-round warm climate like California or Florida. While cold climates may never have commercially available local citrus, it’s surprisingly easy to grow enough lemons indoors to supply your own family in just about any climate.
Seeds started today raised indoors could produce lemons in as little as 3 years (though 5-7 years is more common). Since lemons don’t require a second plant for pollination, a single tree in a sunny window is all you need for fresh, home-grown lemons.
Seeds or Grafted Trees
Lemon trees, like most fruit trees, don’t come “true to seed.” That means that planting the seeds of your favorite lemon variety will result in fruit that’s similar to the parent fruit, but not exactly the same variety. This can be an advantage for indoor lemon growers in cold climates because lemon seeds are easy enough to come by, and germinate easily, meaning that you can start a lot of different seeds and select for the plants that grow the best in your house.
Lemon tree seeds germinate so easily that some people actually grow them densely, planting 20 or more seeds to a pot, and simply use them as an air freshener in their bathroom. The natural fragrance oils produced by the leaves give off a light pleasant smell, but planting them in this way will stunt their growth and you’ll never be able to grow healthy trees and harvest lemons.
The downside of planting from seed is that you cannot get a specialty dwarf variety, and you’ll need to regularly prune back your tree to keep it at a manageable size. Even indoors in a cold climate, a seedling can reach 6 feet tall within the first 2 years. Be sure to cut back the top regularly to encourage a bushy habit.
If you don’t want to deal with lots of pruning or are looking for a named variety like Meyer Lemon, you’ll have to buy them grafted from a nursery center or online source. Plants are usually sold 1-2 years old, which will give your tree a head tart, but they generally are quite expensive, sometimes $100 or more per tree.
While some citrus varieties require lots of heat to bear fruit, lemons, on the other hand, can do quite well indoors without scorching tropical temperatures. Comfortable indoor temperatures, mid 60s to mid-70s, are sufficient to keep a healthy lemon tree, but colder temperatures can be problematic. Even though they don’t strictly require very warm weather, they’ll do better if taken outdoors during the hot summer months for the extra heat and humidity.
Anytime the temperature drops below 55 degrees, your tree will become inactive and take protective measures to avoid damage caused by low temperatures. They’re highly frost sensitive, and even a half hour at or near freezing can kill a lemon tree, so be sure to bring them indoors on cold nights.
Humidity and Air Flow
High humidity combined with good air flow help to keep a lemon tree healthy. An ideal location would be a sunny window in a well-ventilated bathroom, where a bath fan can maintain good air movement to prevent diseases. The occasional boost to humidity provided by hot showers or baths will benefit them in the winter. Near the heat and humidity of a kitchen is also a great option.
While winter humidity will benefit the trees, it’s not strictly necessary. If a humid place cannot be found, just make sure the trees are taken outdoors in the summer and kept in a sunny protected space indoors in the winter. If you notice mold or mildew forming on the plant or soil, increase air circulation with a fan or by moving the plant to a spot with better ventilation.
Sunlight can be a limiting factor for indoor lemon trees, as areas with cold climates also tend to have shorter days in the winter months. In the northernmost parts of the contiguous United States, the shortest days of the year have between 8 and 9 hours of sunlight. A lemon tree needs a minimum of 8 hours of direct sunlight per day to survive, and prefers at least 12 hours to really thrive.
Avoid putting the tree in a spot with filtered sunlight, and opt for a south-facing window to maximize sun exposure. If you don’t have a window with excellent sun available in your house, you can always supplement with indoor plant lighting.
Potting and Fertilizing
A lemon tree requires a substantial amount of root space, and at minimum will need a 16-inch pot. Ideally, your tree would have a pot that’s at least 20 inches (or more). Topping the soil with an inch of well-made compost several times per year is enough additional fertility to keep your tree healthy and productive.
Under ideal conditions, a small 3-foot-tall well-pruned lemon tree will produce as many as 20 lemons per year. While a lemon tree does not require a second tree for pollination, they tend to produce more fruit if there’s more than one tree available to help set fruit. While flowers tend to set fruit readily, if you’re seeing flowers but no fruit, try manual pollination by sticking a cotton swab or small paint brush into each of the flowers.
Have you ever grown lemon trees indoors? What advice would you add? Share your tips in the section below: