Fill a large bowl with cool water. Cut a lemon into wedges, squeeze into the water, and then drop it into the bowl. The lemon will keep the trimmed pieces of artichokes from darkening too much.
Working with one artichoke at a time, rinse under cold running water. Cut or pull away the tough outer petals and trim away any fibrous parts. Cut the trimmed artichokes into eighths. Peel away the outside of the stem. Immediately drop the trimmed artichokes into the lemon water. Repeat with the remaining artichokes. Leave in the water until ready to use. Drain and pat dry with paper towels.