It is possible to grow lemon trees from seed. Unlike other citrus fruit, lemon trees should be kept out of sunlight during germination. Once the tree is planted in a good sunny location outdoors, it can take up to 15 years to produce lemons, according to New Mexico State University. You can also produce exact clones of the tree from a single seed, since one seed can produce multiple sprouts.
Tear off three paper towel sheets from the roll. Moisten each sheet until it is damp, but not wet. Set the paper towels in a pile on top of each other on the table. Fold the group of paper towels in half to form a rectangle. Fold the rectangle in half to form a square.
Slice a lemon in half at the middle. Squeeze one of the halves over the glass to get the juice out. Remove the seeds that are in the pulp; retrieve any seeds that fall into the glass with the juice. Put the seeds on the middle of the folded paper towels.
Fold the paper towels in half with the seeds still in the middle. Continue folding the paper towels to the smallest size possible. This creates maximum coverage and thickness to protect the seeds.
Put the paper towels into a freezer bag. Seal the bag. This keeps the moisture in the paper towels. Put the bag in a warm spot out of the sunlight. Keep the bag away from forced hot air or electric heaters, because the seeds will dry out.
Look for small roots and leaves beginning to emerge in the bag. Unzip the bag. Remove the paper towels and lemon seedlings carefully. Unwrap the seedlings carefully from the paper towels.
Separate multiple seedlings from one seed by gently pulling them apart at the roots. Plant each seedling as an individual tree.
Fill the paper cup with potting soil. Poke a hole in the center of the soil with your finger to a depth of 1 inch. Set a seedling into the hole. Make sure the leaves are just below the soil. Cover the hole with soil.
Move the cup to an eastern facing window that gets half a day of sun or more. Water the soil to keep it moist. Allow the new lemon tree time to outgrow the cup. Meanwhile, look for a permanent location.
Move the sapling outdoors once it has started to split the paper cup. Dig a hole twice the size of the cup in the soil. Set the cup in the center of the hole so the top of the cup is just below the ground. Cut away the cup, making sure to not cut the roots of the lemon tree. Cover the roots with soil. Water the ground around the tree until it is moist.
Repeat the entire process from step 3 onward to plant as many seeds as you want.