Growing a Lemon Tree Indoors - DIY!

Lemon trees are native to North East India, Myanmar and China. Like many other fruit trees their fruit has been used in cooking around the world for thousands of years. They have been grown in Egypt and Iran since 700 AD and are generally grown outdoors in climates much warmer than ours! North America, California, Arizona and Florida (Zones 9-11) commercially grow the most lemons. During a good growing season, one tree usually produces about 272 kg. (600 pounds)!

The benefits of lemons have expanded over the decades. They are rich in Vitamin C and medicinally are still used to treat scurvy. Meyer Lemons are used in naturally acidic cleaning and freshening products. The uses for lemon in cooking are endless and they are also used in the production of skin care and cosmetics.

While we cannot grow lemons outdoors in Canada, they are relatively easy to grow indoors.

A well cared for, an indoor lemon tree or shrub can live for approximately 30 years or more if you have it placed in just the right sunny spot! All lemons begin to flower and bear fruit at approximately 3 – 5 years of age. Lemons will bear fruit once per year. The small white flowers have a beautiful fragrance but not overpowering. Lemons are self-fertile, so there is no need to have two trees for pollination to occur. When the flowers are open, it is helpful to use a very soft paintbrush and gently go from flower to flower to transfer the pollen from male to female or periodically give the tree branches a gentle shake as well. It will take 6-12 months from the beginning of fruit formation to fully ripen.

To successfully grow a lemon tree or shrub indoors some cultural conditions need to be met!

The most important growing requirement is light, so placing the lemon in a south window or sunroom is the best location. They need 8 hours or preferably more of sun per day to be happy. If you find this hard to achieve in your home, set up a grow light near your lemon tree. In Canada, supplemental lighting is a good idea from October to February.

Lemon trees grow best in indoor temperatures between 18C and 25C. Humidity should be 30 – 50%. If you decide to buy a humidifier keep set it to 50% to get enough moisture in the air.

Do not settle them where there is a hot or cold draft.

Lemons prefer to holiday outdoors in the summer. Slowly transition your lemon outdoors ahead of summer once temperatures reach a consistent 10 C or more at night. This is very important as lemons cannot tolerate any frost whatsoever. Over a period of two to three weeks, move the tree from a semi-shady to full sun location. In the fall, re-acclimate to the indoors over a period of 3-4 weeks before the first expected frost date.

Soil and Fertilization

Being a citrus fruit, lemons prefer to grow in a sandy, loam acidic soil. (pH of 5.5 to 6.5) The pot must have drainage and never let the pot sit in water in the catch basin.

Lemon trees benefit greatly from being fertilized with a plant food that is specifically for citrus plants. A slow release citrus fertilizer should be applied once in the early spring and supplemented monthly with a water soluble citrus fertilizer. In the late fall fertilize again with only a slow release citrus fertilizer. In three months time, apply the slow release food again. Do not use liquid fertilizer in the winter.

Watering

Water when the soil is dried down to about two inches in the pot. Water thoroughly so water drains out the bottom of the pot. Err on the side of too little water as opposed to too much, which usually causes root rot. Empty the catch basin after each watering. Citrus must be watered with warm water. If the summer weather is extremely hot, check every second day outdoors for water needs. It may not need watering every second day but do check.

Pruning

For the most part, try to avoid pruning. The fruit forms on the outside branches. If the lemon is way too bushy, you can do some interior thinning. You can also carefully trim off thorns as well.

Propagation

Propagation is by rooted cuttings or grafting. Growing a lemon from seed can be a surprising venture. If the parent plant is a hybrid, the offspring (seed) will not grow to be exactly like the parent plant. To grow a clone of the parent plant you must start it from a rooted cutting or a cutting that is grafted onto a hardier rootstock.

Photo Credit: 1millionwomen.com.au

Repotting

Repot your lemon every 2-3 years in spring and always move up just one pot size at each repotting. You can gently do a bit of a root prune as well if roots look too overgrown and compacted. Do not provide a large container too soon as this will encourage root rot.

Lemon Tree Pests and Problems

Make it a weekly routine to monitor your lemon for pests. Keep an eye out for mealybug, scale, aphids as well as spidermites. Especially after being outside for the summer. When moving it inside for the fall and winter, put pot and all in the shower and give it a warm thorough spraying. I would also do this routinely in the winter every month. Time it to coincide with watering.

Feeding aphids can spread a fungal disease called Tristeza. This disease may progress rapidly or slowly appear. Infected lemon trees may also develop root rot and pitting of the trunk. Symptoms are rapid leaf decline, yellowing and death. The tree becomes stunted, develops less flowers and fruit and may eventually die from this fungal disease.

Lemon Cultivars to Grow Indoors

Lemon trees used in commercial production are usually twenty feet tall or taller. There are smaller varieties that better fit in our homes. Small lemon trees and shrubs can produce many lemons per year if proper growing conditions are met. Most grow to be between 1.5 and 3 m at maturity.

Meyer – A Myer lemon is the easiest lemon to grow indoors. If in a pot, a Myer will eventually reach a mature height of 1.5 m. It is actually not a true lemon as it is a cross between a citron and a mandarin/ pomelo. They have a sweet, less acidic taste but their pH value of 2-3 is very acidic! Because of a very low pH, they are used in natural cleaning products. Lots of thorns. Toxic to cats and dogs.

Eureka - The fastest growing Lemon. Mature size is usually 1.2 – 1.8 m x 60 cm. to 1.2 m. Smooth, bright yellow lemons, shaped like a football. The lemons are produced on the ends of the tree branches. The fruit is seedless with yellow or pink flesh that has a sweet/sour tangy flavor. Can be purchased in bush or tree form. Very few thorns. A true lemon. Extremely toxic to pets.

Ponderosa Bush – This yellow lemon is large with a thick, bumpy and furrowed rind. Toxic to pets. A cross between a Pomelo and a Citron. Very acidic and juicy. Cold sensitive. Flowering and fruiting occur all year long. The maximum mature height you can expect indoors may be 3 m. Large thorns are present on the branches. 

Bearss Bush – At maturity this lemon can grow to 3 meters in height. A juicy, tangy lemon that is very acidic and fast growing. Very few seeds and thorns. Great for juicing. Toxic to pets. A true lemon.

Variegated Pink – This lemon has variegated white, pink and green leaves. The fruit looks like a grapefruit and has a yellow-green skin. The flesh is pink but the juice is clear with a mild tutti-frutti flavor. At maturity it can reach a height of 3 m. Toxic to pets.

Lisbon Lemon – A vigorous grower. Produces an abundance of juicy, acidic, thin-skinned golden – yellow fruit. Very few seeds, if any at all. When grown indoors in a pot the mature height will be about 2 – 2.5m.

FYI - The oldest lemon tree in the United States is a Ponderosa Lemon and was planted in 1900.

Allergies to citrus are common, producing an itchy rash (contact dermatitis). Otherwise they are non-toxic to humans. The essential oils found mostly in the fruits are toxic to animals.

The depressed tiny dots on a lemon skin are actually oil glands that produce a lemony scent as they ripen.

New lemon leaves first come out with a reddish tint. This is not a problem. They will mature to a deep green above and a lighter green below.