The lima bean is a tender annual legume prized for its edible seeds. Classified as a warm-weather crop, its growth rate depends entirely on sustained warmth in both the air and the soil. The speed of the lima bean’s life cycle is highly variable, changing significantly based on the specific cultivar and environmental conditions it experiences.
Initial Growth and Germination Timeline
The initial phase of growth, from planting until emergence, is heavily governed by temperature. Lima bean seeds require consistently warm soil for successful germination. The minimum temperature for reliable sprouting is 65 degrees Fahrenheit, but the process accelerates when the soil reaches an ideal range of 75 to 85 degrees Fahrenheit.
Under these optimal conditions, the seed can successfully germinate and push a seedling through the soil surface in as little as 5 to 8 days. If the soil is only at the minimum 65°F, this emergence period extends to a range of 7 to 18 days. Planting into cold soil, especially below 60°F, can prove detrimental, often causing the seed to rot before it can sprout or leading to a poor, sparse stand.
Total Time to Harvest (Maturity)
The total time needed to reach maturity depends primarily on the growth habit of the chosen variety. Lima beans are categorized into two main types: bush and pole.
Bush lima beans, such as ‘Henderson’ or ‘Fordhook’, are determinate. They grow to a compact height and set most of their pods simultaneously. This allows them to complete their life cycle more rapidly, typically reaching the “shelly” stage (plump, green pods) in approximately 60 to 80 days from planting.
Pole lima beans are indeterminate vining plants that can grow up to 12 feet tall. They continue to flower and produce pods until the first frost. This longer production cycle means they require 75 to 95 days to reach the first harvestable stage. Harvesting for dried beans, where pods are left on the vine until dry and brittle, adds several weeks to the total time, regardless of the variety.
Environmental Factors That Accelerate or Slow Growth
The speed of a lima bean’s development is modulated by several external factors, with temperature being the most significant. Lima beans thrive when air temperatures remain between 70 and 80 degrees Fahrenheit. Temperatures consistently above 90°F can slow growth by causing “flower abscission,” where the plant drops its flowers and developing pods instead of setting fruit.
Sunlight exposure is another factor directly linked to the speed of pod development. The plants require a minimum of six to eight hours of direct sunlight daily to fuel the photosynthesis necessary for rapid growth and the production of plump pods. Insufficient light results in a slower maturation rate and a reduced yield.
Water consistency plays a crucial role in maintaining a swift growth trajectory, particularly once flowering begins. The plant needs about one inch of water per week. A prolonged drought can stress the plant, slowing development and potentially causing it to drop flowers. Excessive water leading to saturated soil can also slow growth by restricting oxygen to the roots, causing poor early growth and disease.