Although you can root a lemon tree with a lemon seed, the tree will not produce fruit for many years. That's because citrus trees grown from seed go through a long juvenile period before maturing to produce seed. To grow a tree that bears lemons quickly, most growers either graft lemon tree cuttings onto the roots of other lemon trees, or start a new tree from a cutting. Some lemon trees, such as Meyer lemons, are easier to propagate as rooted cuttings than through grafting.
Cut the final 8 inches from the tip of several young, green branches. Each cutting should be taken from the branch just behind a point where leaves emerge. Taking cuttings from multiple branches ensures a higher success rate for rooting cuttings.
Place the cuttings in a plastic bag with a small amount of water inside to keep them moist. Store the bag in a refrigerator for safekeeping until you can root your cuttings.
Strip the leaves off the lower 2/3 of the branch, and dip the cut end of the cutting in rooting hormone.
Fill a 5-inch plastic pot with a potting soil formulated for citrus plants. Soil of this type will be half peat moss and half sand, to promote drainage. Insert the cuttings halfway into the potting soil. Mist the soil until it is as damp as a wrung-out washcloth, then cover with a plastic bag and let sit under a grow light or in a sunny windowsill.
Check your cuttings daily and water them to keep the soil moist. Once you see sprouting, remove the plastic bag.