The bluebeard shrub, also called blue mist or blue spirea, is a deciduous perennial that produces gray-green foliage and bright blue flowers in early summer through fall. Bluebeard is a hardy plant that is not attractive to rodents and deer. The shrub is planted as a hedge or in garden beds, where the flowers attract butterflies and bees.
The bluebeard shrub is a variety that offers both a summer and fall visual interest. The shrub grows to a height and spread of 3 feet and has attractive gray-green colored foliage that is aromatic when crushed. Bluebeard shrubs produce bright purple-blue flower clusters July through September and light brown seed heads that are visually appealing in the winter season.
Bluebeard shrubs grow best in a slightly acidic soil that is well-draining with an average amount of organic matter. The soil pH should be tested to verify the pH is approximately 6.0. Ground rock sulfur can be worked into the soil to lower the pH number. The planting area should have full sunlight and receive at least six hours of direct sun. Bluebeard shrubs are considered drought tolerant but should have access to a supplemental water source during the growing season for best results.
The bluebeard shrub requires supplemental water applications during the summer growing season when the weekly rainfall amounts are less than 1 inch. Water applications should be a deep soaking to a depth of 10 inches. The shrub should be fertilized each spring with a balanced fertilizer. Do not apply a high-nitrogen fertilizer as this will stimulate heavy foliage growth but limit flower production. Bluebeard shrubs should be cut back to 3 inches about ground level in late winter to stimulate heavy branch growth in the spring.
Bluebeard shrubs can be propagated to produce additional plants by taking softwood stem cuttings in late spring. Softwood cuttings are taken from new growing plant stems that are soft, yet easily snap when bent. The cuttings are prepared by dipping the cut end of the stem into rooting hormone and sticking it into a tray filled with sterile rooting medium. The rooting tray is placed in a warm location that offers indirect light until the roots are at least 1 inch in length.
The bluebeard shrub is not susceptible to insect or disease problems. The plant is susceptible to root rot if the soil is poorly drained or water pools around the stem for over five hours at a time. Water problems around the root and stem can be prevented by working organic compost into the soil at the time of planting. The bluebeard shrub should be planted in a raised flower bed if the soil is heavy clay.