Plant Doctor Archive

Leggy grevilleas

I HAVE several grevillea shrubs in my garden that are starting to get leggy. I've heard they can die if you prune them the wrong way. What should I do?

MOST grevilleas are relatively shortlived at the best of times and don't respond well to hard pruning - they sometimes simply won't regrow and eventually die.

The best treatment is to trim them lightly but frequently. Don't cut back to hard wood with no leaves - always leave plenty of foliage cover. A light trim several times a year is best. Ideally, start trimming right from when you plant them to encourage a bushy shape, then after each flush of flowers. Wear gloves, as some people come down with a nasty rash if they come in contact with grevillea sap. And don't feed them in the hope of encouraging lots of growth. Like proteas and leucadendrons, grevillea roots are very sensitive to excess fertiliser, particularly those containing phosphates, which most general fertilisers do. Unless they look really starved, don't feed them at all and then only use fertilisers specifically formulated for phosphoroussensitive plants, such as Osmocote Native Gardens.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.