Henry I Blue Aster

Henry™ I Blue Aster (Aster novi-belgii 'Henry I Blue') is a standout fall bloomer that covers itself in a dense display of semi-double blue flowers with hints of lavender and golden-yellow centers. Reaching a mature height of 15 to 18 inches and spreading up to 18 inches, its mounded growth habit makes it an excellent choice for front borders, container arrangements, and mass plantings. Its rich hues bring energy and charm to autumn gardens, making it a favorite among gardeners and pollinators alike.

This compact aster variety thrives in full sun and tolerates light shade, especially in hotter regions. Its deep green, lance-like foliage stays attractive throughout the growing season, providing a striking contrast to the bold flowers. Hardy in zones 4 to 8, Henry I Blue Aster is drought-tolerant once established and resistant to deer and rabbits. Whether planted in cottage gardens, pollinator landscapes, or woodland edges, it offers reliable late-season interest and supports a variety of bees, butterflies, and beneficial insects.

Henry I Blue Aster Care

Plant Henry I Blue Aster in well-drained, moderately fertile soil with a pH between 5.5 and 7.5. Full sun exposure, at least six hours a day, will yield the most flowers, though partial shade is tolerated. Water consistently to keep the soil moist but not soggy, especially during the peak growing season. Avoid overhead watering to minimize the risk of powdery mildew. Apply a slow-release, balanced fertilizer in early spring and supplement with compost or organic matter to enrich the soil. Mulching can help retain moisture and regulate soil temperatures.

Pinch back stems in early summer to promote denser growth and more flowers. After the first frost, cut the plant back to the ground to encourage healthy regrowth in spring. For container plantings, regular watering and occasional staking may be needed to maintain an upright shape, especially in exposed areas.

Henry I Blue Aster Spacing

Space plants 18 inches apart to allow for air circulation and a tidy appearance. For a fuller, massed effect, closer spacing of 12 inches works well. When planting in containers, choose a pot at least 12 to 16 inches wide and deep to accommodate the root system and maintain healthy growth. Position the plant as a centerpiece for container combinations or as a solo focal point for an impactful display.