Lima Bean Plant Profile

Lima beans (Phaseolus lunatus)

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Lima beans, also known as butter beans or chad beans, grow in much the same way as green beans (Phaseolus vulgaris), although they tend to take longer to mature. The smaller varieties are quicker to mature, which is why you see "baby" lima beans for sale more often than the larger beans.

Lima beans have the familiar compound leaves found on other beans—three (trifoliate) oval leaflets that are about 2 to 3 inches long. The plant's flowers are white or yellow and form loose clusters. The resulting pods are curved and flatter than those of common green beans. Lima bean plants are started in spring, from seed or starts, and may not be ready for harvest for two to three months, depending on the variety.

Lima beans have been cultivated in their namesake Lima, Peru, for more than 600 years. All varieties are high in protein as well as several vitamins and minerals. They can be used fresh, frozen, or dried, but they must be fully cooked to be safe. Raw lima beans are toxic to humans.

Botanical Name Phaseolus lunatus
Common Name Lima beans, Butter beans, Chad beans
Plant Type Annual vegetable
Mature Size Bush variety, 2 feet tall; pole variety, 12 feet tall
Sun Exposure Full sun
Soil Type Moderately rich, well-draining
Soil pH Acidic to neutral (6.0 to 6.8)
Bloom Time Summer
Flower Color White or yellow
Hardiness Zones 2 to 11 (USDA)
Native Area North American, Central America
Toxicity Toxic to humans

How to Plant Lima Beans

There are both bush and pole varieties of lima beans available. Like green beans, the bush types will begin setting pods sooner. Bush types grow 2 to 3 feet tall and may need staking when they are covered in pods. Pole beans will need sturdy support, as the vines can easily grow 10 feet or more and become heavy with pods. Plant four to six seeds on each side of a trellis or teepee.

Bush lima beans also tend to set their entire crop at once, so you will be able to harvest from them only for a couple of weeks. If you can succession plant a row every three to four weeks, you will be able to prolong the harvest season. Or, you can plant both bush and pole varieties; this way, you can start the season with the early maturing bush beans and continue harvesting throughout summer from the pole beans.

Lima Bean Plant Care

Light

You will need a spot with full sun to get the most from your lima beans. They thrive best in warm temperatures and long days. In addition to light for growth, full sun exposure will help keep the vines dry and less prone to fungal problems.

Soil

As legumes, lima beans do not need overly rich soil. The soil should be well-draining and moderately rich in organic matter. Heavy clay soil can pose growing problems because lima beans have deep, expansive roots and do not like to sit in wet soil. Soil pH should be in the neutral range of 6.0 to 6.8.

Water

Keep the soil moist until germination, then make sure the plants receive at least 1 inch of water per week. In hot, dry weather, water more frequently and mulch around the roots to keep the ground cool. Pay extra attention once the plants are in flower and start setting pods; they will drop them if they experience drought at this point.

Temperature and Humidity

Lima beans can be a bit temperamental about temperature. They do not like extremes and grow best in climates that stay around 70 degrees Fahrenheit for several months. However, they can handle warm temperatures better than prolonged cool temperatures. Lima beans plants are not frost-hardy.

Fertilizer

Legumes generally do not need extra fertilizer, especially if the soil is already rich. However, since lima beans have a long growing season, it helps to give them a side dressing of compost or composted manure, or a dose of organic fertilizer, mid-season. These slow-releasing sources of nutrients will help the plants continue for the rest of the season.

Are Lima Beans Toxic?

The lima bean is one of those edible plants that is toxic unless properly prepared. Lima beans contain a cyanognic glycoside called linamarin that releases the poisonous compound cyanide when the fresh beans are crushed, including when they are chewed. Commercially grown lima beans sold in the U.S. are regulated for safe levels of cyanide, but no means of regulation exists for plants grown in home gardens. To be safe, soak your harvested beans in water for 24 to 48 hours, then drain. Boil the soaked beans in fresh water for at least 5 minutes before eating them.

Lima Bean Varieties

Breeders are continually working to improve yields and come up with shorter-season varieties. Some varieties are better for long, warm-season climates and others excel in more temperate zones. There are many heirloom varieties still being offered and perform as well as the newer varieties.

  • 'Christmas': These large, burgundy and white beans have a potato-like texture. They are an heirloom variety and take 90 days to mature.
  • 'Jackson Wonder' butter bean: These buff-colored beans have burgundy speckles. They handle heat well as well as a shorter season and take about 66 days to grow.
  • 'King of the Gardens': The most commonly grown variety, this one has large white beans that are produced over a long season (88 days).
  • 'Henderson’s Bush': This is a very old and reliable variety with small white beans. It keeps producing for weeks and grows to maturity in about 65 days.
  • 'Fordhook 242': A heavy producer of medium-sized beans, this variety is a good choice for cooler climates. It takes about 72 days to grow to maturity.

Harvesting

There is wide fluctuation in the length of the season needed to grow lima beans. Some bush varieties, such as Fordhook, might begin producing in 60 days. The heat-loving pole beans, such as Christmas lima, will not start setting pods until about 90 days. If you live in an are with a short growing season, these plants might not be the best choices for your garden. But you can always experiment and try starting the seeds indoors.

Begin harvesting when the pods feel full. They will not plump up like green beans, but you should still be able to see a slight bump. Hold the vine end when pulling off the pods to prevent damaging the vine.

How to Grow Lima Beans From Seed

Lima beans have big seeds, and they can be direct sown 1 to 2 inches deep. Space bush varieties about 4 to 6 inches apart, although you can also scatter the seeds in a wide row and thin them, if necessary.

If you have a short season and want to grow pole limas, consider starting the seeds indoors three to four weeks before your last frost date, in peat or paper pots. Or, warm the soil in the spring with a layer of black plastic, then direct sow the seeds with some protection around the seedlings, such as a row cover or a windbreak of plastic or straw bales. The soil needs to be at least 65 degrees Fahrenheit for good germination. If you are not pre-warming the soil, wait for two to three weeks after your last frost date to direct-seed.

Common Pests and Diseases

All the usual bean pests will seek out your lima beans plants. Heading the list are bean beetles and aphids. Keep watch and tackle any problems while they are small. Many four-footed pests also love tender, young bean seedlings. Fencing is recommended. Groundhogs can defoliate entire bean teepees in a few minutes.

The biggest disease problem is root rot, which you should be able to avoid with well-draining soil. If you have a particularly rainy season, be sure to turn off your automatic irrigation during this period.

How to Grow Lima Beans in Pots

Bush lima beans can be grown in containers, but you may need several containers for a practical harvest. Choose containers that are 12 inches wide and at least 8 inches deep, and fill them with potting soil or a mix of well-draining soil and compost. Support the plants with a teepee made of bamboo stakes or a similar structure. Closely monitor the soil moisture, which can drop quickly in pots, and make sure the plants stay well watered.