Harvesting lemongrass differs from pruning. As a fast-growing plant, lemongrass can withstand harvesting when plants are young, and there won't be any adverse effects on its growth. Although the green leafy portions of the plant are too tough to eat, you can snip them for steeping in tea or broth. The juicy stalks are edible when mashed or minced, adding a fragrant lemon note to dishes. Use a hand trowel to remove individual stalks, roots and all, from the clump. Remove the tough outer leaves and prepare the tender white stalks by chopping, or freeze whole stalk pieces for later use.