Bottlebrush plants (Callistemon) get their common name from their bristly and typically red flowers that look like a traditional bottle brush. The plants mostly flower in the spring and summer. They grow at a moderate rate and can be planted at any point during the growing season in their hardiness zones. They have an upright growth habit with fairly short, narrow leaves. Plus, they're popular desert perennials because they're colorful, inexpensive, low-maintenance, drought-resistant, and readily available.
|Common Name||Bottlebrush, Little John|
|Plant Type||Flowering perennial desert shrub|
|Mature Size||Up to 15 feet tall|
|Sun Exposure||Full sun|
|Soil Type||Loamy, moist, well-draining|
|Soil pH||5.6 to 7.5|
|Bloom Time||March to September|
|Flower Color||Red, white, yellow, green|
|Hardiness Zones||8 to 11|
How to Grow Bottlebrush
Bottlebrush plants aren't the fastest growers. But they come in a variety of sizes, with the largest reaching around 15 feet tall. Dwarf varieties grow up to 3 feet and make a nice low shrub for under windows or borders. Because of their bright flowers, they attract nectar-feeding birds, such as hummingbirds. However, they also appeal to bees and wasps, which is something to consider before planting if anyone in your home has a bee sting allergy.
For best results, you’ll want to pick a planting location that gets lots of sun and has excellent soil drainage. With the right environment, bottlebrush will need very little care from you. Expect to water only if you have a long stretch without rain, and occasionally prune your plant if you need to clean up its appearance.
Bottlebrush plants produce the most flowers when they're planted in full sun. They will tolerate partial shade, but they likely won't produce flowers when planted in full shade.
You can determine the sunniest spot in your yard by making a map of your growing area and recording where the light falls throughout the day. Begin by checking where the sun hits the ground first thing in the morning, and then draw a corresponding circle on your map. Repeat this process at noon and again in the evening. The section where all the circles overlap is the sunniest location—ideal for your bottlebrush.
While they can survive in most soils, bottlebrush plants prefer loamy and moist ground. It's especially important that their growing area is properly drained. If your soil is poor or full of clay, you can mix in compost and topsoil before planting. A rototiller might be required for this task if the soil is difficult to loosen by hand.
Bottlebrush plants only have moderate water needs. However, while they are somewhat drought-tolerant, these shrubs will need some sort of water source to remain healthy during long dry spells. They also won't survive in locations with standing water, which can cause root rot. So avoid planting in lower areas of your yard where water can collect.
Temperature and Humidity
Bottlebrush plants can tolerate very high temperatures and prefer low humidity. They don't do well with frost. If freezing temperatures are predicted, the shrubs can benefit from being wrapped with some muslin or a sheet. But they won't survive in prolonged temperatures below freezing. So if you live north of their hardiness zones, plan to move your bottlebrush inside for the winter.
While not required, applying a low-phosphorous fertilizer in the spring can help bottlebrush flourish throughout the growing season. An additional application after the plant has been pruned can help encourage new growth.
Potting and Repotting
Bottlebrush is a versatile genus. Its various species can be grown in a range of pot sizes, as well as planted in the ground. The dwarf varieties such as 'Little John' can be trained and shaped to look like miniature trees, which are especially nice when placed on either side of a front door.
If you wish to replicate the features of the parent plant, propagating bottlebrush by cuttings is the optimal technique. Semi-mature wood branches of the shrub produce more offshoots, making them ideal for cuttings.
Take a 6-inch cutting from semi-mature wood in the summer. Then, take off the lower half of the leaves, as well as any flower buds. Use a rooting hormone, and plant the cutting in soilless potting mix. Keep the container moist; you can put a clear plastic bag over it to help lock in moisture. In about seven to 10 weeks, your cuttings should have formed roots and be ready for planting.
Regardless of which species you plant, bottlebrush needs occasional trimming to stay looking neat and to enhance the next season's blooms. You can lightly prune at any point in the year without seriously affecting how the plant flowers. But save more extensive pruning for late winter or after the plant goes through its first flowering cycle of the spring. This can help to encourage further blooms throughout the growing season.
Common Pests and Diseases
Most issues arise for bottlebrush plants when they're planted in soil that's too wet or when there's too much moisture on the plants themselves. The diseases that can result from overwatering include mildew, fungus growth, and root rot. Some common signs of these diseases include a white powdery (or otherwise abnormal) substance on the foliage or a wilting plant. Preventing these conditions is far preferable to treatment, so if you notice soggy soil you might have to move your plant to a new location or into a container with better drainage holes.
Varieties of Bottlebrush
There are around 50 species of bottlebrush in the Callistemon genus, ranging in size from dwarf bush to tree. Some varieties include:
- Callistemon citrinus: Known as crimson bottlebrush or lemon bottlebrush, this plant grows around 5 feet tall, and its foliage has a lemony scent.
- Callistemon salignus: This plant is known as white bottlebrush because its flowers are a creamy white.
- Callistemon viminalis: Known as weeping bottlebrush, this plant reaches around 15 to 20 feet tall with drooping branches reminiscent of the weeping willow.