Grevillea Knockout

Grevillea 'Knockout' (Grevillea 'Knockout') is an Australian bred hybrid that carries red toothbrush flowers over a long season on a shrub about 2.5m tall and 2.5m wide. It grows fast, asks for little, and honeyeaters find it within days of planting. For a native screen that flowers rather than just fills space, it is among the easiest we sell.

Why you'll love it

• Red flowers over a long season. The toothbrush blooms peak through the cooler months and keep coming in flushes, so there is rarely a bare stretch.
• Honeyeaters move in. The nectar load is heavy enough to hold wattlebirds and lorikeets in an ordinary suburban garden.
• Fast cover from a small plant. It puts on real size in the first two years, which makes tube stock a sensible way to plant a long boundary.
• Built for hard spots. Frost hardy, drought tolerant, salt tolerant and happy in poor soil, so coastal blocks and dry inland gardens both suit it.

Where it works best

Screening and privacy. Plant 1.5m apart for an informal screen around 2.5m high. The result is soft and layered rather than a flat clipped wall.

Coastal gardens. Salt and wind tolerance make it a front line shrub on a beach block, holding its foliage where more refined plants burn off.

Mass planting. Grouped in threes or fives at 1.5m spacing it covers a bank, verge or median with almost no upkeep, and a single plant still reads well as a flowering feature.

Growing Grevillea Knockout in Australia

Position and climate. Full sun gives the heaviest flowering; part shade thins the bush and cuts the display. It suits subtropical, warm temperate, cool temperate, Mediterranean and arid gardens, and handles frost once established.

Soil. Sharp drainage is the one real requirement. Sandy and gravelly soils suit it. On clay, plant on a mound raised 300mm and go easy on rich compost, because grevilleas resent wet soil far more than poor soil.

Water and feed. Water weekly through the first summer, then it largely looks after itself. Use a low phosphorus native fertiliser only. Standard garden and lawn fertilisers can kill a grevillea outright.

Pruning. Tip prune lightly after each flush to keep it dense and to set the height. Avoid cutting back into bare old wood, because it reshoots poorly from stems carrying no leaves.

What to expect when it arrives

It is sold as tube stock, as packs of ten 140mm plants and as packs of six 200mm plants. Tube stock is the value choice for a boundary run and catches up quickly. The 140mm and 200mm plants arrive bushier and bring a screen forward by a season.

Tough narrow foliage travels well, so plants arrive in good order, perhaps with a little leaf bronzing. Allow a quiet month while the roots move out, then fast growth and flowers within the first year. Plants are delivered Australia wide, with delivery from $29.95. Every plant is covered by our 30 day healthy plant guarantee.

Plant care guides and related reading

• Read our grevillea care guide for feeding and pruning detail.
• Compare forms and heights across the grevillea collection.
• Build the habitat out with more bird attracting plants.
• On the coast, see what else copes in salt tolerant plants.

Common questions

How far apart should I plant it for a screen?

A metre and a half apart in a single row. Any tighter and the lower branches shade each other out, leaving the base thin exactly where you want cover.

Can I clip it into a formal hedge?

No. It takes a light trim and holds a rough height, but the habit is open and arching, so a sheared face looks wrong and cutting into old wood leaves gaps.

How fast does it grow?

Quickly for a native shrub. With sun and drainage it reaches close to full height in two to three years, slower in cool temperate and arid gardens.

Why do grevilleas suddenly die?

Almost always wet feet or the wrong fertiliser. Improve drainage before planting and feed only with a low phosphorus native blend.