How to Grow and Care for Lentil Plants

The lentil plant is an annual, a legume, and a member of the Fabaceae family, like peas or beans. 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 bloom on the lowest branches and move up the plant until harvest. Flowers fade about three days after bloom and produce seed pods three to four days later.

Each flat, smooth seed pod is half to a quarter of an inch long and contains one or two seeds. These cool-season legumes grow relatively fast. Plant them in spring, and they should be ready for harvest after about 80 days.

How to Plant Lentils

Lentils are easy to grow and very hardy. Sow the lentil seeds in late April to early May, three weeks before the last frost date. Young plants can tolerate light frost. Plants will likely be shorter if sown later, and pods will mature later and less prolifically.

This plant needs full sun and grows well near cucumbers and summer savory. They like loamy, acidic soil but can grow in alkaline soil too. Do not plant where other legumes have grown in recent years or with onions or garlic.

Plant the seeds 1 to 2 inches deep—space one inch between seeds and 18 to 24 inches between rows. Give growing plants a short trellis; if no support is added, 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 on the south or east, where the sun is warmest and will encourage little seedlings to grow quickly.

Soil

Overall, lentils adapt to all soil types, but good drainage is critical. Plants prefer sandy loam soils that are well-drained and fertile. Avoid saline, boron, or sodic soils, which may limit root growth and the plant's ability to intake moisture. A pH of 6.0 and 6.5 is best (though the plants will grow in a soil pH of up to 8.0).

Water

Upon planting, water well without making the soil soggy. Give plants about 1 inch of water per week. At least 10 inches of annual rainfall is needed. If weather conditions become especially dry, lentil plants are drought tolerant. However, the plants may 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 cool and with 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

You don't need fertilizer; use compost and tea to enrich the soil. If your soil is naturally clumpy, add compost to loosen it in the fall before spring planting, as direct contact with fertilizer may shock the seeds. Before you plant the seeds, use an inoculant to boost the plant's nitrogen. 

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

Pollination

Blooms self-pollinate before opening and have an extremely low level of natural cross-pollination.

Types of Lentil Plants

Lentils are divided into two subspecies: the cultivated variety (Lens culinaris) featured in this guide and its wild relative (Lens orientalis). The seed coat of lentils can be clear, green, pale tan, brown or black; some cultivars have purple, black mottles or speckles. There are many varieties, here are a few:

• Brewer: Large, brown, most common variety
• Green Eston: Green, smaller than other lentils
• Red Chief: Light tan coating with a red seed
• Masoor: Red seed, brown coat
• Puy: French lentil; blue-green speckled
• Avondale: A medium-sized green lentil; large yield; another common variety in the United States
• Beluga: Black variety; so named because it looks like caviar

Green Lentils vs. Split Peas

Split peas are sometimes confused for green lentils. Split peas and lentils are both members of the legume Fabaceae family. Split peas are peas or Pisum sativum; they are a dried field pea that has had their outer skin removed and is split in half. Lentils are the seeds from inside pods, kept whole.

Harvesting Lentils

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

To tell if it's ready to be harvested, hit a seed with a hammer. 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.

Two ways to separate pods from seeds:

1. Place pods in a pillowcase. Tie shut and jog on it. (Yes, jump on it.) Pour the seed mixture from basket to basket in front of a fan that is on a medium setting. Store seeds at 0 degrees Fahrenheit or colder for five or more days; at this temperature, it will kill any bean weevils that are still inside.
2. Dry in a heated air dryer at no higher than 110 degrees Fahrenheit. The lower heat will reduce the risk of seed coat cracking.

Once you've removed the dry lentils from the pods, store them in an airtight container, which will last for one year.

How to Grow Lentil Plants in Pots

Lentils can be grown in containers, but several plants are required to have a good yield. Use sandy or loamy soil that is more acidic, about 6.0 pH. You can use any pot as long as it's at least 8 inches deep with ample drainage holes.

Plant two to three seeds per pot at least 1/2 inch deep. Do not use more seeds; it will crowd them, not allowing proper air circulation and producing a smaller yield. Water after 5 hours of planting, keeping the soil moist at least 1 inch deep. If growing them indoors, they will need 8 to 10 hours of full light; supplemental grow lights work well.

Pruning

If you have planted several seeds per pot, prune or pull the weaker seedling. Removing weaker seedlings allows stronger plants to grow more vigorously and prevents crowding in the growing area. When the seedlings have sprouted a few leaves, evaluate which looks weaker or is not growing as strongly as its neighbor seedlings. Carefully pull, and do not disturb the roots of the plant you're leaving in the pot.

If you notice plants beginning to grow densely together, remove some foliage to allow for airflow around the plants. Restricted airflow around plants is a breeding ground for disease and pest infestations.

Lentils have difficulty competing with weeds, so hand-pull any weeds or competing plants. Also, remove diseased or pest-damaged lentil plants to prevent the spreading of disease or pests.

Since lentils are annuals, once they mature, dry out, and are ready for harvesting, pull the entire lentil plant from the ground. Grasp it close to the ground, and it should easily lift up with no resistance.

Propagating Lentil Plants

Lentils are often grown for their value as a high nutritional food source, providing iron, protein, and other vitamins and minerals. Lentils are propagated by sowing seeds in the spring. You can directly sow the seeds of this annual plant in the ground starting as soon as the last frost. It lasts up through the hot summer months. It is not propagated by cuttings or division, although you can transplant seedlings that you get started indoors two weeks before the estimated last frost date. Winter-tolerant varieties must be planted in late summer or early fall.

How to Grow Lentil Plants From Seed

Before planting, optionally, you can inoculate lentil seeds with Rhizobium leguminosarum, a bacteria that lives in a mutualistic symbiotic relationship with legumes. Spreading this bacteria on the seeds will give the plants the added nitrogen they need for ideal growth and health. Inoculate the seeds on the day of the seeding. Dampen the seeds and roll them in the powdered inoculant to coat them. 

Till and rake the soil well and remove any stones and weeds to ensure seeds have the proper conditions to germinate. Plant the seeds 1 to 2 inches deep—space one inch between seeds and 18 to 24 inches between rows. Seeds germinate in about 10 days, and plants mature in 80 to 119 days.

Provide a trellis and train the plant to climb it; they will climb independently, but it helps to give them a start, and you can use plant ties to help secure the stem to the trellis for extra support.

Common Pests and Plant 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 you notice them, hose them down with a steady stream of water or pinch them off.