There are several factors to consider when harvesting green beans. You'll get the best flavor and texture if you pick you beans at the right time.
You should usually try and harvest your beans when the plants are dry. Let the morning dew evaporate before harvesting.
The bean pods do not need to reach a certain length before harvesting them. Some of the pods will be long and thin, others will be short and fat. The size variance will not affect the flavor of the green bean. The more important factor is texture.
The green bean pods should be firm, crisp, and show no visible bulges. A bulge will indicate that the green bean is over-ripe. It will still taste good but might have a limp texture. A perfectly ripe green bean will make a snapping noise when broken into pieces. This is why some folks call green beans "snap beans".
As the plants will continue to produce green beans over a long period of time, great care should be taken to not damage the plant when harvesting green beans. Use one hand to hold the stem and use your other hand to pick the bean. The blossom end of the stem will usually still be attached to the bean after you pick it. If you don't hold the stem, you risk breaking off other blossoms or branches or yanking the whole plant out of the ground by the roots. Take care of your green bean plants and they will take care of you.
After harvesting green beans, store them on the kitchen counter with the stems on. Once you remove the stems, keep them in the refrigerator.
The stems usually snap off easily. The long, fibrous strip that runs the length of the pod should also be removed. Some varieties of green beans do not have this fibrous strip. The beans can then be snapped into any size you like.
If you want to wait more than a few days before eating your freshly picked beans, blanch them in boiling water for 3 minutes. Then plunge the beans into ice water for 3 minutes. This will help the beans retain their bright, green color. Place the cooled beans in an air tight bag and put them in the freezer. They will keep for up to 1 year.
Our favorite way to store beans is to can them. We put up 50+ quarts per year and during the harvest season, our pressure canner is constantly working. We pack clean jars with fresh beans that have been rinsed and drained. We pour boiling salted water over the beans and then attach the lids and rings and process in a pressure canner according to the manufacturer's instructions.
If you want dry shell beans, just leave the beans on the plant until they turn brown and dry out. When they are ready, you should be able to gently shake the pod and hear the beans rattling around inside. You can then pick the pods, shell the dried beans and store them in an air tight jar, bag or other container.
After the growing season is over, pull the green bean plants up by the roots and add them to your compost pile.
Now that you have a bunch of green beans, you should be ready for a few recipe ideas...