Richardson, Texas is located in United States Department of Agriculture plant hardiness zone 7, and is the perfect climate to grow tiger lilies, which are hardy in zones 3 to 9. Since they are bulbous plants that require a chilling period in order to grow and bloom, plant tiger lilies in the late fall in zone 7. Like most lilies, they require at least six hours of sunlight, and since summers can be scorching hot in Richardson, an area that receives morning sun and light shade in the afternoon is ideal.
Remove flowers when they begin to fade and wilt. Simply pinch or cut them off and your tiger lilies will use their energy to produce more flowers rather than seed.
Water your tiger lilies weekly with enough water so that when combined with rainfall, they receive at least 1 inch of water a week. Since Richardson's summer days can be extremely hot (averaging highs of 96 degrees F), you may need to water them twice a week with 1 inch of water to keep the lilies well hydrated.
Mulch your tiger lilies with about 2 to 4 inches of mulch. Use organic mulch, such as bark, leaf mold or wood chips, which will also decompose and add valuable nutrients to the soil. Mulch will help retain water in the summer months, as well as keep the soil cool. Lilies do not prefer hot soil, as is common during Richardson's summer. Mulch will also help maintain soil temperatures during the winter months.
Fertilize your tiger lilies in the spring when it appears the plants are growing rapidly. Use a fertilizer labeled 5-10-10 or 6-24-24. Read the label for proper dosing amounts since each fertilizer is different. If you use a granular fertilizer, water the lilies with 1 inch of water immediately after fertilizing.
Keep the foliage intact even after the tiger lilies are finished blooming. Only cut off the foliage after it browns and wilts. This usually occurs after the first frost in the fall, usually in November. At this time, reapply the mulch so that it totals 2 to 4 inches.
Divide and transplant tiger lilies when they become overcrowded. Do this in the fall after you have cut the foliage or in early spring before new growth appears. Dig up your tiger lilies, which are usually planted about 6 inches beneath the soil and separate the bulbs with your hands (new bulbs grow on the parent bulb) and replant them about 12 inches apart in an area that receives at least six hours of sunlight.