Nitrogen response of proteaceous shrubs and other nursery plants grown in containers

Abstract

A range of proteaceous shrubs and other nursery plants were grown in containers with soilless media and various N levels primarily supplied from Osmocote (26 percent N). Plants demonstrated a range of responsiveness. Grevillea robusta was the most responsive but required an optimum near to 120g N/m3/month; two Eucalyptus species showed a smaller response than G. robusta but required an N optimum of 97g N/m3/month. Camellia japonica and Erica herbacea (Syn: E. carneal ) 'Springwood White' responded best to the range 57 to 121 g N/m3/month. G. rosmarinifolia and Leucadendron adscendens were the next most responsive species, then Hakea laurina and Dryandra formosa. Leucospermum candicans, Protea repens, P. scolymocephala could grow satisfactorily on very low N levels, amounting to just over 5g N/m 3/ month from Osmocote 18/2.6/10. Optimum N rates for all these species are discussed.