Lemon (Citrus x limon)

If you’re wondering how to grow a lemon tree, you’ve arrived at the right place. Lemon trees are truly lovely additions to the home garden or orchard given their lacy spring blossoms and bright yellow, tart fruit. This small evergreen tree can be grown in the soil in warm-winter climates or in a container that is overwintered indoors.

I. Appearance and Characteristics

The lemon (Citrus × limon) is a species of small evergreen tree in the flowering plant family Rutaceae, native to Asia, primarily Northeast India (Assam), Northern Myanmar, and China.

The origin of the lemon is unknown, though lemons are thought to have first grown in Assam (a region in northeast India), northern Myanmar, or China. A genomic study of the lemon indicated it was a hybrid between bitter orange (sour orange) and citron.

The origin of the word lemon may be Middle Eastern. The word draws from the Old French limon, then Italian limone, from the Arabic laymūn or līmūn, and from the Persian līmūn, a generic term for citrus fruit, which is a cognate of Sanskrit (nimbū, ‘lime’).

The lemon tree produces an ellipsoidal yellow fruit.

• Chemistry

Lemons contain numerous phytochemicals, including polyphenols, terpenes, and tannins. Lemon juice contains slightly more citric acid than lime juice (about 47 g/L), nearly twice the citric acid of grapefruit juice, and about five times the amount of citric acid found in orange juice.

• Varieties

The ‘Bonnie Brae’ is oblong, smooth, thin-skinned, and seedless. These are mostly grown in San Diego County, US.

The ‘Eureka’ grows year-round and abundantly. This is the common supermarket lemon, also known as “Four Seasons” (Quatre Saisons) because of its ability to produce fruit and flowers together throughout the year. This variety is also available as a plant for domestic customers. There is also a pink-fleshed Eureka lemon with a green and yellow variegated outer skin.

The Lisbon lemon is very similar to the Eureka and is the other common supermarket lemon. It is smoother than the Eureka, has thinner skin, and has fewer or no seeds. It generally produces more juice than the Eureka.

The ‘Femminello St. Teresa’, or ‘Sorrento’ originates in Italy. This fruit’s zest is high in lemon oils. It is the variety traditionally used in the making of limoncello.

The ‘Yen Ben’ is an Australasian cultivar.

II. How to Grow and Care

Sunlight

Lemon trees thrive in full sun, which in this case is between six to eight hours of daily sun.

Temperature and Humidity

Lemon trees are best grown in warm and humid states. They are the most sensitive to cold weather of all the citrus fruits and thrive in temperatures that range from 75 to 85 degrees Fahrenheit. They also prefer the humidity levels to be as close to 50 percent as possible.

Young trees are particularly sensitive to cold conditions and they should be brought indoors if temperatures take an unexpected drop.

Watering

Getting the watering requirements right with your lemon tree is crucial for a successful harvest. The trees prefer low to moderate rainfall. During the period of establishment, more frequent watering will be required—even as much as once or twice a week. Once mature, lemon trees develop more drought tolerance.

During the summer months, the soil should be kept moist, especially for young trees. Be careful not to cause water logging as boggy conditions are problematic. Overwatering results in yellowing leaves, which then drop, along with fruit drop and root rot.

Soil

All citrus trees thrive in soil of medium texture and moderate depth with a slight acidity. Soil that is well-drained is an absolute must as root rot is a problem in soggy conditions. Mulching should be avoided to prevent pooling water.

Fertilizing

Like other citrus fruit trees, lemon trees are energy-hungry. Use a complete NPK (nitrogen, phosphorus, potassium) fertilizer to encourage healthy growth and fruit production. A deficiency in nitrogen, magnesium, zinc, iron, or potassium also causes varying degrees of yellowing leaves.

Pruning

The different lemon tree varieties have different growth habits, and this can impact pruning requirements. Regardless of variety, prioritize pruning long lateral branches for fruit growth or main leaders for aesthetics. You want a wide canopy to maximize fruit growth.

Pinch foliage to control the shape and encourage bloom. Prune young trees to encourage good branch structure. The upright growth habit of the Lisbon lemon tree means it needs more regular pruning to maintain a strong canopy and good food production.

Propagation

Of all the citrus fruit trees, lemon trees are one of the easiest to propagate from cuttings. Semi-hardwood cuttings can be taken from late spring to early summer when a tree is in active growth. Then take these general steps to propagate your lemon tree.

• Cut a cutting that is 3 to 6 inches long. Make sure the cutting comes from healthy, new growth that has not yet produced fruit or flowers.
• Remove all but the top two sets of leaves from the cutting and dip the bottom end of the stem into rooting hormone powder.
• Pot the cutting in a 1-gallon container that is filled with well-draining, moist medium.
• Keep the cutting warm and ensure the humidity level by putting a clear plastic bag over the pot.
• Place the container in a bright location and keep it moist by misting it every so often.
• In about two months, check for roots by gently tugging at the cutting to see if it resists your pull.
• Remove the plastic bag and keep it sheltered in a bright spot until the spring when the plant is ready for its permanent home.

Growing From Seed

Though it is typically discouraged from propagating a lemon tree from seed because of very spotty and disappointing results, it can be done. You will need to be patient and have lower expectations about the quality of the tree or fruit it will produce. Here are the steps:

• Extract a few seeds from a mature lemon and clean them off with water.
• Soak the seeds in a bowl of water for 24 hours to soften the outer coat.
• Toss floating seeds (they are not viable) and remove the seed coatings from viable seeds.
• Plant surviving lemon seeds in a small container filled with potting soil. Put them about 1/2 inch to 1 inch deep in the soil.
• Water the pot and place it in a bright and warm space that hovers around 70 degrees Fahrenheit, and keep the pot moist but not soggy.
• Look for germination in a few weeks and keep warm until you can plant the seedling in a more permanent spot.

Potting and Repotting

When potting any type of lemon tree, choose a large 5-gallon or larger container. Make sure it is at least 15 inches tall. There should be numerous drainage holes in the container. Take these steps:

• Fill the container halfway with a potting mixture made for citrus trees.
• Take the tree out of its original pot and begin to manually fluff any matted roots.
• Place the tree in the new container and begin to fill in the sides of the tree with potting mixture. Do not go above the crown of the roots. Gently press the soil as you fill in the container.
• Water the tree immediately. Pot-grown trees will require more frequent watering than their in-ground counterparts.

Overwintering

If you’re bringing the lemon tree indoors, place your plant in a well-lit location that is not too warm. In winter, low indoor temperatures similar to early spring will actually encourage flowering. Bring it outdoors in late May to encourage natural pollination and let the fruit grow in the warmer spring and summer temperatures. Return the plant indoors in September.

Lemons are not fans of dry air, indoors or outdoors. If you are concerned, misting or using a humidifier could be beneficial.

Pests and Diseases

The downside of a lemon tree is that it does attract a host of pests and plant diseases.

Pests, such as the citrus leaf miner, aphids, and various types of scale insects and mites, are all frequent visitors of lemon trees.

Many diseases that can affect a lemon tree and leave yellowing leaves or disfiguring marks on leaves, flowers, and fruits. Here are five common ones to watch for:

• Citrus canker: One of the most common plant diseases is citrus canker, which presents as pinpoint spots on leaves that enlarge and develop a yellow halo. A tree in full sun, along with fungicide treatments, can help the lemon tree survive.
• Melanose: Sunken lesions that then become raised, rough to the touch, then crack, is a symptom of melanose, another fungal problem that occurs during rainy conditions.
• Citrus scabs: Corky growths on leaves, stems, and fruit may be citrus scabs, which are controlled by a copper-based fungicide.
• Greasy spot disease: Yellow spots that turn into brown blisters on leaves indicate greasy spot disease, which is a fungus. This disease occurs during humid, very wet weather.
• Citrus greening: Citrus greening, a bacterial disease, results in yellow blotchy leaves and disfigured fruit.

III. Uses and Benefits

Culinary uses

Lemon juice, rind, and peel are used in a wide variety of foods and drinks. The whole lemon is used to make marmalade, lemon curd and lemon liqueur. Lemon slices and lemon rind are used as a garnish for food and drinks. Lemon zest, the grated outer rind of the fruit, is used to add flavor to baked goods, puddings, rice, and other dishes.

• Juice

Lemon juice is used to make lemonade, soft drinks, and cocktails. It is used in marinades for fish, where its acid neutralizes amines in fish by converting them into nonvolatile ammonium salts. In meat, the acid partially hydrolyzes tough collagen fibers, tenderizing it. In the United Kingdom, lemon juice is frequently added to pancakes, especially on Shrove Tuesday.

Lemon juice is also used as a short-term preservative on certain foods that tend to oxidize and turn brown after being sliced (enzymatic browning), such as apples, bananas, and avocados, where its acid denatures the enzymes.

• Peel

In Morocco, lemons are preserved in jars or barrels of salt. The salt penetrates the peel and rind, softening them, and curing them so that they last almost indefinitely. The preserved lemon is used in a wide variety of dishes. Preserved lemons can also be found in Sicilian, Italian, Greek, and French dishes.

The peel can be used in the manufacture of pectin, a polysaccharide used as a gelling agent and stabilizer in food and other products.

• Oil

Lemon oil is extracted from oil-containing cells in the skin. A machine breaks up the cells and uses a water spray to flush off the oil. The oil–water mixture is then filtered and separated by centrifugation.

• Leaves

The leaves of the lemon tree are used to make tea and for preparing cooked meats and seafoods.

Other uses

• Industrial

Lemons were the primary commercial source of citric acid before the development of fermentation-based processes.

• Aroma

Lemon oil may be used in aromatherapy. Lemon oil aroma does not influence the human immune system, but may contribute to relaxation.

• Other

One educational science experiment involves attaching electrodes to a lemon and using it as a battery to produce electricity. Although very low power, several lemon batteries can power a small digital watch. These experiments also work with other fruits and vegetables.

Lemon juice may be used as a simple invisible ink, developed by heat.

Lemon juice can be used to increase the blonde color of hair, acting as a natural highlight after the moistened hair is exposed to sunlight. This is due to the citric acid that acts as bleach.

IV. Harvesting and Storage

It’s natural for the flowers to develop into fruit and still take a year to mature to yellow and be mature for harvest. Leave the lemons on the tree to ripen. Like other citrus fruits, they will not ripen off the tree.

Each fruit packs citric acid and plenty of vitamin C. Welcome lemons into your garden and you’ll have nutritious, cheerful fruits to last a lifetime. They are perfect for adding to meal recipes and even as an environmentally friendly cleaning option.