How to Grow Bottle Brush
Evergreen bottle brush shrubs (Callistemon spp.) Fill gardens throughout U.S. Department of Agriculture plant hardiness zones 8 through 11 with stunning spring-to-summer color. Cylindrical, bushy-stamened flowers in a assortment of yellow, red or yellow appear brighter against needle-like, gray- to deep-green leaf. Hummingbirds flow to the nectar-rich blossoms. Bottle brush alternatives consist of tidy cultivars, such as 4-foot-high and wide “Compacta,” and 10- to 12-foot shrubs suitable for privacy screens, such as scarlet bottlebrush (C. citrinus). Grown in the perfect place, bottle brush thrives for decades using a minimum of maintenance.
Select a planting site in sunlight with well-drained, dry to moist soil. Bottle brush performs best in acidic to mildly alkaline soils with pH readings between 5.6 and 7.5. Foliage on plants in highly alkaline ground often develops chlorotic, or yellowing, from chlorophyll reduction.
Plant bottle brush at autumn when cooler temperatures decrease pressure in the rooting plant and winter rains help it build with a minimum of supplemental irrigation. Set it at an inward-angled hole measuring three to five times the width of its root ball at the very top and twice its breadth at the base. Make the hole deep enough that the top of the main ball protrudes 1/4 into 1/2 inch over its edge.
Water bottle brush whenever its leaf begins to wilt, or so the top 3 to 4 inches of soil are dry to the touch, during its first growing season. Once its origins are well established, water only during prolonged dry periods. Slow, deep watering using a drip system or soaker hose encourages deep, deep drought-resistant roots.
Feed the tree with a slow-release, 8-8-8 fertilizer in spring and summer. Apply the fertilizer according to the manufacturer’s recommendations.
Prune bottle brush straight after its new growth emerges, but prior to the tender tissue has hardened and set flower buds. Pruning to remove spent blossoms also keeps it tidy. After several years, cutting all of the branches to the floor and also providing the tree an extra dose of fertilizer results in vigorous development.
Scrub bottle brush for Dictyospermum scale infestation. The yellowish-brown, 1/16-inch barnacle-shaped pests colonize and consume sap from the tree’s foliage. While they seldom cause enough damage to warrant therapy, blasting the plants using a powerful jet of water removes the insects.
Watch the shrub for yellow leaves, a sign of iron deficiency. Treat the issue by applying iron chelate into the ground at a rate of 0.8 to 1.6 oz per 100 square feet. The program remains effective for up to three years.