I have been sprouting the same jar of aduki beans for about a week and they still are really short sprouts - ie not ready to be eaten! Before that I soaked them overnight and put them out and nothing happened for 2 days so I soaked them for another 1-1 and 1/2 days then put them out again.
Why do you think they are sprouting so slow? Does this happen when beans are older or there is less sun or something? What other reasons could it be?