The effect of phosphorus on the growth of Grevillea ‘Poorinda firebird’ in soil-less potting-mixtures

Abstract

Grevillea ‘Poorinda Firebird’, an Australian member of the Proteaceae family, was found to grow poorly in soil-less potting-mixtures. The use of phosphorus fertilizers at rates normal for other plants was shown to be the main cause. Leaf symptoms which accompanied the growth reduction are fully described. Normal growth was produced if soil was included in the mixture or, with soil absent, if Osmocote 18-4.8-8.3 (7–9 months release rate) was used without any other form of phosphorus present.