Place a coffee filter at the bottom of a 4-inch pot. Fill the pot with potting soil to within 1/4 inch of the rim. Lightly press on the top of the soil with your fingers to firm it. Fill one pot for each seed you want to plant.
Fill a bowl with water. Remove the seeds from the tangelo orange and place them into the water. Wash the seeds to remove the pulp.
Dry the tangelo seeds on a paper towel and then place one into the center of each pot.
Push the seed below the soil, about 1/3 inch deep, with your finger. Backfill the hole with soil to cover the seed and lightly firm the soil in place.
Fill a shallow container, like dishpan, with 3 inches of water and place the pots in the water. Allow the pots to soak until the top of the soil is visibly moist.
Remove the pots to a drainage rack so the extra water can drain away.
Cover the pots with clear plastic and place them in a warm, bright location. Don't place them in direct sunlight, this will be too hot for germination.
Check the soil every day for moisture. Keep the soil moist, but not soggy. It can take two to eight weeks for the seeds to germinate. Remove the plastic when the seeds have germinated.
Transplant the tangelos into a 6-inch pot when there are three sets of true leaves.