Edamame (also known as green or garden soybean) is super easy to grow and harvest, but it's not always so easy to know when to harvest. There is a really narrow window of opportunity (only a matter of 3 to 4 days) to harvest edamame at its best. Just a day too late, and the sweet, tender, nutty beans will be starchy, woody, and dull. Here's a quick guide to harvesting edamame that will help take some of the guesswork out of the process:
To make sure you don't miss that window of opportunity, keep a close eye on edamame pods as they start to fill out. Once the pods start to plump up and fill out, pick one of the larger pods every day or so and see how they look and taste. There will be some variability by variety, but in general the pods should still be bright green (if they are starting to yellow a bit, they have gone too far), and the beans should also have a nice green color and be about the size of your index finger fingernail. I find that flavor is overall the best indicator, though, and ripe edamame will have a pleasant nutty flavor and very tender texture. If you think they look and taste ready, then they usually are--and it's time to act quickly!
If you miss the harvest window and the beans are past their peak, it's best to just let them continue to dry on the plants and save the seed for next year (confession: this is how I ended up with about 3 years worth of edamame seed last summer - oops!).
Unlike other garden beans that produce continuously, edamame pods ripen all at once and the plants will not set another crop after harvest, so the most efficient way to harvest is to simply go down the row, pulling the plants out by the root (check out those beautiful, nitrogen fixing nodules!). I simply stack them up, and the haul the pile off to a comfortable place in the shade to start pulling the pods off the plants - it really is that easy!
Oh, and the plants are packed with nutrients, so after the harvesting has been complete, be sure to chop up the plants (leaves, stems, and all) and add them to the compost pile or even directly back into the garden as mulch to build up the nutrient levels in the garden soil for next year.
Once the pods have been harvested, it's best to use or freeze them immediately, but fresh edamame will store in the refrigerator for no longer than a week (or one year if frozen). If you plan to freeze edamame, blanch the pods in boiling water for 3 minutes before packaging for freezing (this will destroy the enzyme that will take a toll on the quality of the beans over time, thus the encouragement to use them up as quickly as possible). If you prefer, the beans can be shelled from the pods prior to freezing, but I find it much easier to freeze the pods (the beans will slide right out after they are cooked in the pods).