Collect the green buckeye fruit soon after they fall from the trees in autumn. Remove the green husk (fruit) to reveal the brown buckeye inside. Fall is the best time to plant, immediately after collecting the seeds. Soak the seeds in water for 24 hours. Plant them 3 inches deep, either directly in the ground or in moistened seed starting soil. Keep evenly moist (but not soggy) for three weeks or until they germinate. Wash hands after handling, since the fruit and seeds are toxic.
During the first winter, protect the seedling by mulching the ground around it.