How to Grow Lentil Plants

Rows of Lentil plants (Lens culinaris Medik.) grow in fresh soil.

Mathia Coco / Getty Images 

The lentil plant is an annual legume crop divided into subspecies: the cultivated variety (Lens culinaris), which will be discussed in this guide, as well as its wild relative (Lens orientalis). This member of the legume family(Fabaceae) is a relative of beans. Lentils offer high nutrition through B vitamins, minerals, and protein.

Lentils are easy to grow and very hardy. Plants grow on branched vines averaging 12 to 24 inches tall. This slender, semi-erect plant can be grown with a single stem or free to grow in a branched bush.

White, light purple, or pale blue flowers begin blooming on the lowest branches and move up the plant until harvest. Blooms self-pollinate before opening. About three days after bloom, flowers fade and produce seed pods three to four days later. These cool-season legumes should be planted in spring and can be harvested around 80 days after planting.

Each flat, smooth seed pod is half to a quarter of an inch long and contains one or two seeds. The seed coat is usually clear, green, pale tan, brown or black; some cultivars have purple, black mottles, or speckles.

Botanical Name Lens culinaris
Common Names Lentil plant, Adas, Mercimek, Messer, heramame, masoor
Plant Type Annual crop
Mature Size 12 to 20 inches tall (18 to 24 inches between rows)
Sun Exposure Full sun
Soil Type Well-drained, fertile, sandy loam
Soil pH 6.0-6.5 (up to 8.0)
Bloom Time Spring
Flower Color White, pale blue, light purple
Hardiness Zones 5-11, USDA
Native Area Egypt, Greece, and Rome

How to Plant Lentils

Good companion plants for lentils are cucumbers and summer savory. Do not plant where other legumes have grown in recent years, or with onions or garlic.

Native to Egypt, Greece, and Rome, Lens culinaris has likely been grown for more than 8,500 years. Over time, this crop made its way to the Mediterranean, Asia, and then the Western Hemisphere. Since the 1930s, lentil plants have been rotated with wheat.

Give growing plants a short trellis, or, if no support will be added, be sure to space plants 5 inches apart so the air can circulate between them. Lentils don't compete well with weeds.

Lentil Plant Care

Light

Select a location that gets full sun, preferably oriented on the south or east where the sun is warmest and will welcome little seedlings to grow quickly.

Soil

Overall, lentils adapt to all soil types but the key is good drainage. Plants prefer sandy loam soils that are well-drained and fertile. A pH of 6.0 and 6.5 is best (though the plants will grow in a soil pH up to 8.0).

Avoid saline, boron, or sodic soils, which may limit root growth and the plant's ability to receive moisture.

Water

Upon planting, water well without flooding. Give plants about 1 inch of water per week. At least 10 inches of annual rainfall is needed. If weather conditions become especially dry, know that lentil plants are drought tolerant and may even die if the soil becomes waterlogged. Stop watering when pods begin to dry.

Temperature and Humidity

Lentil plants thrive in areas where the weather is somewhat cool and where there is limited rainfall such as eastern Washington, northern Idaho, and western Canada, among other locations in North America. Ideal temperatures are around 65 to 85 degrees Fahrenheit and the humidity should be on the lower side—30 to 40 percent is ideal.

Fertilizer

If your soil is naturally clumpy, add compost to loosen it in the fall prior to spring planting as direct contact with fertilizer may shock the seeds.

Instead, inoculate seeds with Rhizobium leguminosarum. This will give the plants the added nitrogen they need for ideal growth and health.

Next, dig a long trench on the side of each row of young plants when they are about 5 inches tall. Pour in compost tea and repeat when the plants start to flower.

Lentil sprout germination
Germinating lentil sprout Ali Majdfar / Getty Images
Lentil plant in bloom
White blooms on lentil plant BasieB / Getty Images
Harvested, dried lentils
Harvested and dried lentils Ali Karimi Dahlan / EyeEm / Getty Images

Harvesting Lentils

Collect green pods within 70 to 80 days of planting to eat them like snap beans. When lentils are used as a dry grain, the seed is called a pulse. In late July and early August, harvest lentils when the lower pods are brown.

Hit a seed with a hammer and if it cracks, then it's ready to be harvested. If it mashes, let it dry on the plant longer. In the event of an early frost, pull the whole plant and hang it upside down in a warm environment to dry. Do this while outdoor temperatures are not extremely hot or dry.

These are two ways to separate pods from seeds:

  1. Place pods in a pillowcase. Tie shut and jog on it. (Yes, jog on it!) Pour the seed mixture from basket to basket in front of a fan that is on a medium setting. Store seeds at zero degrees Fahrenheit or colder for five or more days; this will kill any bean weevils that are still inside.
  2. Dry in a heated air dryer at no higher than 110 degrees Fahrenheit. This will reduce the risk of seed coat cracking.

How to Grow Lentil Plants From Seed

Till and rake the soil well and take out any stones and weeds to ensure seeds have the proper conditions to germinate.

Sow the seeds in late April to early May, three weeks before the last frost date. Young plants can tolerate light frost. If sown later, plants will likely be shorter and pods will mature late and less prolifically.

Plant the seeds 1 to 2 inches deep. Space one inch between seeds and 18 to 24 inches between rows. Seeds will germinate in about ten days and plants will mature in 80 to 119 days.

Winter-tolerant varieties must be planted in late summer or early fall.

Common Pests/Diseases

Because lentil plants thrive in low humidity, they usually do not attract many diseases. Occasionally blight, white mold, or root rot may occur as a symptom of rotating lentils with the wrong crops.

In addition to wheat, corn is another good option for crop rotation. Rotate every three or four years. Avoid fava bean, field bean, field pea, mustard, canola, rapeseed, soybean, sunflower, sugar beet, and potato because they are susceptible to some of the same diseases.

Pests are minimal too. It is very rare for lentils to attract Lygus bugs, aphids, maggots, wireworms, and thrips. If found, just hose or pinch them.