Compared to other beans species, the larger size and thicker seed coat of lima beans means germinating them in the garden can take some time. While you can simply plant dried lima beans without any treatment, soaking them in lukewarm water first will increase the speed at which the beans will sprout. Soaking allows the water to pass through the seed coat, saturate the interior of the seed and trigger the germination process. After soaking, you can then plant your lima beans in your garden with a head start on sprouting.
Prepare your seeds for planting in spring when the soil has warmed and there is no risk of frost. Lima beans are not cold-tolerant.
Place the lima beans in a cup of lukewarm water for one to four hours, depending on the size of the beans. Larger beans need a longer time for water to enter the bean. Remove the beans from the water after this time.
Dry the lima beans with a paper towel. Dust the lima beans with legume inoculant, available at your home improvement or garden center, to provide the beans with the nitrogen-fixing bacteria they need to grow well. The dust should adhere well to the still damp beans.
Plant the seeds immediately in warm, rich soil that drains well in an area of your garden that receives plenty of sun.