Check the size and color of your Brussels sprouts. They should be green and in tightly formed buds that are approximately 1 inch in diameter, about the size of a walnut.
Wait for the first frost before you harvest them. The temperature should be around freezing when you pick them - this is said to produce the best flavor.
Hold each sprout in your hand and firmly twist or cut it from the stalk. Only harvest a few at a time from each stalk, so that the season is prolonged.
Choose only tightly formed, green sprouts. Avoid those with yellow leaves or those that have opened.