Grevilleas are ever flowering, ever popular and there is an ever-increasing number of new cultivars released each season. This genus ranges from groundcovers to trees and can have some widely different requirements and tolerances, so check the individual labels. But for an overview of how to have success with Grevilleas read on.
Water in well when planting, using a weak seaweed solution is beneficial. Do follow up watering (not if raining) for the next 6 weeks to allow for ideal growing conditions. You want the plant to get established and for the roots to grow well. Hot dry windy conditions may require extra watering. Once well established, Grevilleas can survive extended dry periods, but all grow and flower better with the occasional good soak.
Light and Location
Usually prefers full sun, but can take some shade. A minimum of 6 hours full sun is preferable. Pick your site well. An established grevillea will not move well – not at all. Protect from strong winds.
A few are frost tolerant – many are not – be sure to check the label.
Use a native fertiliser. Many are sensitive to phosphorus, it is safer to assume they all are. Feed in early spring and again in late summer.
• Many grevilleas seem to flower all year, which makes the conventional nursery axiom of ‘prune after flowering’ a bit problematic. However they generally have a major flush of flowering and it is after this flush that cutting back by up to one third will help promote bushy growth. If you still can’t work out when to prune – opt for pruning in October and follow up with tip prunig after flowering. When pruning, be aware that sometimes the leaves can prick and cause a mild skin irritation.
• Mulching is very beneficial for grevilleas. They like the moisture retaining qualities and the additional organic material supplied to the soil as it breaks down. Keep away from the stem of the plant to avoid any chance of collar rot.
Pests and Diseases
• Can suffer root rot in heavy clay soils. Ideally plant on a slope so drainage is OK or use raised beds. If your grevillea suddenly looks sick, rapidly loses leaves and dies – it is probably root rot, and there is no coming back from it.
• Some are prone to a dark mould that seems to stain the stems (eg Grevillea Moonlight), spraying with a copper based fungicide can help with this.
• Grevilleas attract a lot of birds. Some sip the nectar and others feast on the nectar feeding insects, and at the same time clean up other damaging insects.