Himalayan blue poppies are one of the few flowers that produce an intense sky-blue blossom. In their native location in China, they can grow to more than 6 feet tall; in other locations, they average 20 to 28 inches tall. These poppies look best planted in mass displays or threaded throughout a border. These flowers are not a good choice for the impatient gardener; in some locations they may not bloom the first season. The foliage will die down for the winter and you should expect to see blooms the second year. If it is prevented from blooming the first time the bud sets, the poppy is more likely to become a perennial. These flowers are suitable for USDA zones 3 to 8.
Select a site for the Himalayan blue poppies. These plants need partial, dappled shade and protection from strong, drying winds. The soil needs to be rich and well-drained and, in colder climates, it needs to be acidic. Several weeks before planting, dig up the soil, remove rocks and other garden debris and test the pH level. If the soil is too alkaline, amend it with sulfur. Add plenty of organic matter to enrich the soil.
Plant the poppies in early spring. Dig a hole that is larger than the poppy's container. Remove it from the container and gently loosen the roots with your fingers. Place the poppy in the hole, add soil to fill in the hole and tamp down gently to remove air bubbles. Water gently to settle the soil. Space the poppies 18 to 24 inches apart.
Water the poppies regularly, but do not over water; waterlogged plants can suffer from crown rot. However, do not let the soil dry out between waterings. Give them a light application of general fertilizer in the spring. Downy mildew can be a problem, especially in locations with high humidity. Spray with a fungicide at the first sign of mildew.
Watch for the Himalayan blue poppies to bloom beginning in early summer and continuing through to early fall. Unless you want the seed to ripen, remove spent flower stems. After all growth dies down, cut the poppies to ground level. Use a plant marker to indicate the location of the poppies.
Propagate the poppies from fresh ripe seed in the fall or spring. After the seeds have sprouted, thin the seedlings to 18 to 24 inches apart. Water well initially, but back off so as not to over water.