Oriental hybrid lilies are exotic flowers that grow up to 5 feet tall with blooms that are available in pink, red and white. Their underground root stems called bulbs are hardy in USDA hardiness zones 5 to 10 and are best planted in the fall. In colder zones, Oriental hybrid lilies should be planted in the spring after the last frost.
Prepare a planting site in full sun or in an area with morning shade and afternoon sun. Till the top 12 inches of the soil to make the soil more conducive to water drainage. Mix in 2 to 3 inches of organic matter, such as sand, compost or peat moss.
Dig holes that are 8 inches deep. Space multiple bulbs 4 to 6 inches apart.
Plant the bulbs by setting one bulb in each hole with the tip facing up. Backfill the soil, tamp it down and water the planting bed.
Spread mulch, such as bark or wood chips, over the planting bed to the depth of 2 to 3 inches. This will help keep the bulbs warm during the winter, especially in zones 5 and 6, and will help the soil retain water.
Cut away dead foilage close to the ground after the booms die in the fall. In zones 5 and 6, add 2 to 3 more inches of mulch to keep the bulbs warm. In colder zones, dig up the bulbs and store them in an open container of moist peat moss in an area around 35 degrees F. Plant them again in the spring after the last frost.