You may have heard that you can’t grow a fruiting tree from a store-bought lemon. This isn’t exactly the whole truth. Any grocery store lemon has seeds that can grow into a tree. Seed-grown citrus trees take longer to produce fruit than commercial grafted trees, but fruit it may in about six or seven years. The lemons won’t be exactly like the one you take the seeds out of, but they’ll be lemons. Thriving only in U.S. Department of Agriculture planting zones 9 through 11, lemons sprout quickly and easily from seeds. This makes a seed-grown lemon tree a good way for kids to grow their own houseplant, even in cooler regions.
Peel a fresh lemon. Gently pry the sections apart. Pinch the center of each section to squeeze the seeds out without damaging them. Pick out the largest, fattest seeds and discard the smaller ones. Rub the remaining seeds between your fingers under cool running water until they’re not slippery anymore. Fill a drinking glass about half full with water and put the seeds in the glass. Remove any floaters and throw them away because they’re not viable. Soak the rest of the seeds for about eight hours, then plant them right away.
Mix equal parts sterile commercial potting mix and Perlite. Fill a plastic nursery six-pack with the soil. Put the pack in a shallow container of warm tap water. Remove the pack from the water when the soil surface feels evenly moist to your touch. Let it drain for 30 minutes to an hour.
Plant a lemon seed 1/4 inch deep in the center of each cell. Close the seed flat up in a clear plastic bag. Prick the bag with a fork several times to make holes to allow air to circulate around the germinating seeds. Set the pack in a warm room out of direct sunlight. The best temperature range is between 70 and 75 degrees Fahrenheit. Because bottom heat is best, a spot above a hot water heater or on top of your refrigerator is ideal. Your lemon seeds should sprout in about one to three weeks.
Open the bag every day to check the soil surface. Don’t let it dry out. Use a plastic spray bottle to water enough to keep the soil evenly moist but not soggy or wet.
Take the plastic bag off for good when the lemon seeds germinate. Move the seedlings to a bright windowsill in a warm room. Keep them out of direct sun. Water enough to keep the soil surface evenly moist but don’t allow it to become soggy.
Plant the lemon seedlings in individual 6-inch pots of sterile commercial potting mix when they‘re about 4 to 5 inches tall. Move them to a sunny windowsill in a warm room. Citrus trees require at least four to six hours of direct sun daily. Water enough to keep the soil surface evenly moist.
Feed the seedlings ammonium sulfate (21-0-0) in March after they’re about 6 inches tall. Dissolve 1 tablespoon ammonium sulfate in 1 cup of warm water for each seedling. Water the seedlings with the fertilizer solution. Repeat the applications at six-week intervals until the end of August. Never feed citrus during the cooler months.