How to Trim an Artichoke: 1. Fill a large bowl with cold water; squeeze the juice of 1 lemon and drop in the lemon halves. Working with one artichoke at a time, saw about 1 inch off the top using a serrated knife. 2. Snap off the tough, dry leaves around the stem (about 2 layers of leaves). 3. Use kitchen shears to trim 1/4 to 1/2 inch off the thorny leaf tips. 4. Peel the stem with a paring knife or cut off the stem completely if you want the artichoke to sit flat. Rub the cut parts with a lemon half, then keep the artichoke in the lemon water while you trim the rest.