Bottlebrush Callistemon ‘Harkness’

Bottlebrush 'Harkness' (Callistemon 'Harkness'), also sold as Gawler Hybrid, carries the biggest crimson brushes of any bottlebrush in common cultivation, and it carries them over a long season. It grows to about 5m tall and 3m wide, fast enough to screen a boundary in a few years and tough enough to do it on a difficult site. Few Australian natives ask this little and give this much back in birdlife.

Why you'll love it

• Very large crimson flowers. The brushes are noticeably bigger than a common bottlebrush and open over a long season rather than in one short burst.
• A magnet for birds and insects. Honeyeaters and lorikeets work the flowers daily, and bees and butterflies follow them in.
• It grows almost anywhere. Frost hardy, drought tolerant, salt tolerant, happy in poor soil, and one of the few natives that tolerates wet feet as well.
• Fast to useful height. Quick growth to around 5m makes it a practical screening tree rather than a slow ornamental.

Where it works best

Screening and privacy. Plant 2m apart for a tall screen. At that spacing the canopies knit into a continuous wall while each plant still has room to flower properly.

Windbreaks and coastal gardens. A staggered double row at 2m spacing filters wind instead of blocking it, and the salt tolerance means an exposed coastal boundary does not burn.

Driveways and feature planting. Grown on a single trunk it makes a small flowering tree for a drive, spaced 4m apart, or a standout specimen in a native garden.

Growing Bottlebrush 'Harkness' in Australia

Position and climate. Full sun for the heaviest flowering; part shade thins both growth and flower. It suits warm temperate, subtropical, cool temperate, Mediterranean and arid gardens, and it is frost hardy enough for cold inland winters once established.

Soil. Almost anything. It handles poor, sandy and clay soils, and unlike most natives it copes with ground that stays damp, which makes it useful in a low spot or beside a drainage line.

Water and feed. Water weekly through the first summer, then only in extended dry periods. Feed a low phosphorus native fertiliser in early spring. Standard high phosphorus fertiliser can damage the roots.

Pruning. Trim immediately after each flush, cutting just behind the spent brushes. That keeps the plant dense and encourages the next round of flower. It reshoots readily from old wood, so a leggy plant can be cut back hard to reset it.

What to expect when it arrives

This one is supplied in 45L pots, which is advanced stock: a well branched plant with real height and structure on arrival rather than a young shrub you wait on. It is the size to choose when you want a screen working sooner.

The pot is heavy, so have the hole dug and help arranged before delivery day. Some leaf drop and a few spent flowers after transit are normal. Expect visible new growth within about six weeks in the warm months. Delivered Australia wide, and advanced and large stock is freighted at cost. Every plant carries our 30 day healthy plant guarantee.

Plant care guides and related reading

• Read the callistemon care guide for pruning and feeding detail.
• Compare the full bottlebrush range.
• Browse other bird attracting plants to plant alongside it.

Common questions

How far apart should I plant it for a screen?

Two metres apart in a single row. Closer than that and the lower branches shade each other out, which leaves gaps near the ground where you most want cover.

Can I keep it lower than 5m?

Yes. Trim after each flowering flush and it holds comfortably at 2m to 3m as a tall hedge. Because it shoots from old wood it stays furnished at the base rather than lifting into bare trunks.

Will it cope with a wet or boggy spot?

Better than most. It tolerates wet feet, so it suits a low corner of the garden or a swale that holds water after rain, while still handling drought at the other extreme.