Conkers are funny little seeds. Shed from the horse chestnut in the fall, they litter yards and streets. When clearing them from your yard to save your bare feet, collect a few and set them aside for planting. Horse chestnut trees are easy to start from conkers. Simply plant them in the fall and wait for nature to take over in spring. To avoid disappointment after a long winter wait, plant twice as many as you think you will need. A few out of the harvest are bound to be inviable.
Place a roughly 1/4-inch layer of broken pottery shards or gravel in the bottom of the pot to encourage drainage.
Plant the seed 2 inches deep in the center of the pot.
Water the soil only when it is dry to the touch (stick your finger into the soil to check).