Grevilleas

Start with the form, not the flower

The flowers will win you over either way, so choose on size and habit first. For groundcover, 'Mt Tamboritha' hugs the ground at 40cm tall and 1.5m across, 'Forest Rambler' spreads to 2m at just 50cm high, and 'Winter Delight' carries pink and red spider flowers through the coldest months. For borders, pots and small gardens, 'Mini Marvel' stays under 1m and flowers most of the year. In the middle sits 'Robyn Gordon', the most planted of all at 1.5m tall and 2.5m wide with red brushes almost year round. For screening, 'Moonlight' reaches 4m and 'Honey Gem' 4.5m, both fast. At the top end, Brown Silky Oak makes an 8m feature tree and Southern Silky Oak (Grevillea robusta) a genuine 15m shade tree for acreage.

Matching grevilleas to your climate

All of them want full sun and free draining soil. From there, breeding decides. The low spreaders bred from south eastern alpine species, Mt Tamboritha, Winter Delight, Forest Rambler and 'Lilliane', are frost hardy and suit Melbourne, Canberra, Hobart and the hills, though Winter Delight sulks in humid summers and is a poor choice north of Sydney. The reverse applies to the big Queensland hybrids: Robyn Gordon, Honey Gem and Red Silky Oak thrive from the tropics through subtropical and arid gardens but handle light frost only. Perth and Adelaide gardeners have the widest choice from our Australian native plant range, since most are built for dry summers and take little water.

Planting and spacing

Drainage decides success. On heavy clay, mound the bed 200mm to 300mm high rather than digging deep, and never add rich compost or manure to the hole. Space groundcovers 1m apart for full cover within two seasons, Mini Marvel at 80cm, Robyn Gordon and 'Superb' at 1.5m, screening varieties at 2m and Brown Silky Oak at 3m. Water deeply once or twice a week through the first summer, mulch 75mm deep, then step back: an established plant needs almost nothing.

Feeding, pruning and the phosphorus rule

Grevilleas are phosphorus sensitive. Feed only with a low phosphorus native fertiliser, once in spring, and skip the blood and bone. Tip prune after each flowering flush from the first year, because a plant clipped little and often stays dense for a decade, while one left alone goes woody in the centre. Wear gloves when pruning: the foliage of Robyn Gordon and Superb can irritate sensitive skin.

Common questions

Which grevilleas handle frost?

The low growers bred from southern species: Mt Tamboritha, Winter Delight, Forest Rambler and Lilliane are all frost hardy. The large flowered Queensland hybrids take light frost only, so in cold districts plant them against a warm wall or choose the southern types.

Can I use normal fertiliser on them?

No. Standard fertilisers and manures carry too much phosphorus, which yellows the foliage and can kill the plant over time. Use a native specific low phosphorus blend once a year and they will not ask for more.

Will they really bring birds?

Yes, and quickly. The brushes are nectar factories, and varieties like Robyn Gordon and Mini Marvel that flower most of the year feed honeyeaters through winter when little else does. Our guide to designing a native garden for wildlife shows how to layer them.

Why did my grevillea die suddenly?

Almost always root rot from wet feet, and it can take out a healthy looking plant in a fortnight of summer rain. Plant into a mound on clay soils, keep mulch off the trunk and resist the urge to water established plants.