Citrus seeds are unusual in that they normally carry only the genes of the mother plant. This is known as vegetative or nucellar reproduction. After germination, the seeds may produce up to three sprouts, two of which grow quickly and are identical clones of the parent. If present, the smaller third sprout emerges between the other two. This sprout is a hybrid and will not come true to the mother plant. The straggler sprout should be removed by pinching it off to ensure that only the stronger sprouts will grow on.
Slice the citrus open and remove the seeds. Rinse the seeds thoroughly in lukewarm water and place them on damp paper towel to keep them moist.
Make a drainage hole in the bottom of each cell of the planting tray, if needed. Fill the tray with potting soil and add just enough water to moisten the mix.
Plant the seeds in separate cells of the tray, roughly 1/2 inch below the soil's surface. Slide the planting tray into a large plastic bag and seal it. This will keep the humidity high in the bag, simulating a greenhouse.
Place the bag in a warm location but not near direct heat. The top of a cupboard or refrigerator are good spots, as rooms are usually warmer towards the ceiling.
Check the soil every few days to make sure it is still moist. Add water sparingly, as needed.
Take the planting tray out of the bag when the seeds sprout and place it in a warm, sunny location such as a windowsill. If any seeds have grown three sprouts, pinch off the smallest one. It usually takes 10 to 14 days for the seeds to sprout. Add water as needed to keep the potting mix moist.
Transplant the seedlings after they have grown at least two sets of leaves. Plant each seedling in a 4-inch pot with regular potting soil. Keep the soil moist and give the plants plenty of sunlight.