Grow in average, medium moisture, well-drained soil in full sun. Becomes weedy and sparse with diminished flowering performance if not grown in full sun. Does poorly in wet, poorly draining conditions. Will adapt to clay soil if properly amended. Removal of spent flower spikes during the growing season will encourage additional bloom. This hybrid is one of the least winter hardy of the buddlejas, and is only recommended for growing in USDA Zones 6-9. Therefore, in order for this plant to survive in the St. Louis area (Zone 5b-6a), it should be grown in a protected location with a winter mulch. Regardless of winter protection, in Zone 6 the top growth of this plant may die to the ground in winter with roots surviving. Even if plants do not die to the ground, they usually grow more vigorously, produce superior flowers and maintain a better shape if routinely cut back to a framework close to the ground in late winter each year in somewhat the same way one would prune back a crepe myrtle (Lagerstroemia). Blooms on both new and old wood, so loss of top growth to winter weather or late winter pruning will not eliminate flowering for the growing season. Grow in average, medium moisture, well-drained soil in full sun. Becomes weedy and sparse with diminished flowering performance if not grown in full sun. Does poorly in wet, poorly draining conditions. Will adapt to clay soil if properly amended. Removal of spent flower spikes during the growing season will encourage additional bloom. This hybrid is one of the least winter hardy of the buddlejas, and is only recommended for growing in USDA Zones 6-9. Therefore, in order for this plant to survive in the St. Louis area (Zone 5b-6a), it should be grown in a protected location with a winter mulch. Regardless of winter protection, in Zone 6 the top growth of this plant may die to the ground in winter with roots surviving. Even if plants do not die to the ground, they usually grow more vigorously, produce superior flowers and maintain a better shape if routinely cut back to a framework close to the ground in late winter each year in somewhat the same way one would prune back a crepe myrtle (Lagerstroemia). Blooms on both new and old wood, so loss of top growth to winter weather or late winter pruning will not eliminate flowering for the growing season.