The United States Department of Agriculture scores or grades lima beans intended for sale in the United States. The score for each crop of inspected lima beans is based on the quality of of a sample section of that crop. While only government officials can give official USDA scores for lima beans, you can score your own crop of lima beans to see how they measure up to government standards.
Harvest and collect your lima bean crop.
Set aside 10 percent of the crop or a reasonably countable amount of lima beans--around 100 beans or more.
Give your lima beans a grade for color. Count the number of lima beans that are true to color for their variety (at least 50 percent of the bean must be the appropriate color to be counted). Then divide that number by the total number of lima beans in your sample. If more than 93 percent of the lima beans are true to color, then grade them between 54 and 60. If between 93 and 60 to 65 percent of the beans are true to color, score them between 48 and 53. If between 60 and 20 percent of the beans are true to color, then score them between 42 and 47. If less than 20 percent of the lima beans are true to color, then score them between 0 and 41.
Give your lima beans a grade for defects. A defective bean is one that is broken, sprouted, shriveled, discolored or otherwise odd. Count the number of defective beans, and divide that number by the total number of beans. If between 1 and 5 percent of the beans are defective, score the beans between 36 and 40. If between 5 and 10 percent of the beans are defective, score the beans between 32 and 35. If between 10 and 15 percent of the beans have flaws, score them between 28 and 31. If more than 15 percent of the beans are flawed, score them between 0 and 27.
Add the scores your beans received in steps 3 and 4. If the number is above 90, your lima beans are grade A. If the score is between 80 and 89, the beans are grade B. If the score is between 70 and 79, they are grade C. If the total is below 70, they are considered substandard lima beans.