The kohlrabi bulb which grows above the ground should be harvested when the diameter is between 2 and 4 inches or a little bigger than a golf ball but smaller than a tennis ball. If the bulb gets too big it will be very woody and too tough to eat. I typically pull the entire plant including the root and use a sharp knife to take off the stem. Then I cut the leaves of the bulb.
If you store the kohlrabi bulb in a plastic container in the refrigerator, it will last for about a week or longer. I have not tried these two options but I hear that you can store kohlrabi for about a month in a cold cellar (which I don’t have) or longer if you freeze it.
My preference for eating kohlrabi involves peeling the bulb and then grating it on top of a salad or using it in coleslaw instead of cabbage. You can also slice it like a radish.
Some people steam or cook the bulb and cook the leaves. I haven’t tried that yet!
Don’t forget to take a look at my prior blog titled “Kohlrabi May Be From Another Planet”