Fill the jam jar with 1 to 2 inches of small pebbles and then a few inches of compost. The pebbles will help with drainage.
Remove the seeds from a ripe orange and press them gently into the compost. Avoid planting too deep. Sprinkle a little warm water on top. Using water that's too cold will shock the seeds. Do not overwater, as the seeds will not thrive in soggy or water-logged soil.
Cover the top of the jar with a plastic bag and secure with a rubber band. Place the jar in a sunny spot or near a radiator. The best temperature for germination is anywhere between 60 to 70 degrees F. It will take between two weeks to two months for the seeds to start germinating.
Remove the healthiest seedling and plant it in the small pot filled with potting soil. The recommended time to remove seedlings is when a few leaves have opened. Cover the pot with a loose plastic bag and close the top.
Water every three to four days with warm water. Do not allow the soil to dry out. Place the pot in a warm spot. Your orange plant can grow in this pot until it is large enough to survive outdoors. If you are using a dwarf variety, you can transfer the plant to a large pot.