Lima beans are a warm season crop native to Central America. They are highly nutritious, containing high levels of iron, protein, thiamine, and riboflavin. While lima and snap beans are similar in many respects, lima beans do have specific cultural requirements.
Lima beans require a minimum soil temperature of 65 F for germination. Therefore, plant lima beans about 2 weeks after the average frost free date in your area. In central Iowa, lima beans are normally planted from May 20 to June 30. While both bush and pole lima beans are available, bush-type varieties usually perform better than pole varieties in the midwest.
Sow seeds at a depth of 1 to 1 1/2 inches. Rows should be spaced 2 feet apart with the seeds spaced 2 to 4 inches apart within the row. After germination, thin to 4 to 6 inches between plants. Fordhook 242 (large greenish white seeds, heat tolerant), Baby Fordhook (small green seeds), and Henderson's Bush (small white seeds, early maturing) are suggested bush-type varieties for Iowa.
In the midwest, yield is largely determined by weather conditions. Lima beans grow best when temperatures are between 70 and 80 F. They also require 1 inch of water per week (either from rain or irrigation) during blossoming and pod development. Hot, dry conditions during blossoming may cause many of the flowers to drop off without setting pods. Excessive nitrogen fertilization promotes lush growth, but may also inhibit pod formation.
Bush-type lima beans should be ready to harvest approximately 65 to 75 days after planting. Harvest lima beans when the pods are well-filled and bright green. Yields will vary considerably due to temperature, moisture, and other factors. Unshelled lima beans can be stored at 32 F and 90% relative humidity for up to 10 to 14 days. Surplus can be shelled and frozen or canned.
This article originally appeared in the May 11, 2001 issue, p. 53.