Plant Doctor Archive

Poorly protea

WE purchased a Protea nerifolia 'Alba' about three months ago and the leaves at the bottom of the bush are turning black.

BEING closer to the soil surface (where the humidity is highest) during the prolonged wet weather of the last couple of months is the most likely cause. In the wild proteas grow in extremely open sunny habitats with lots of fresh air blowing around them, so their leaves are adapted to dry conditions and don't tolerate cool, damp situations well. As long as the foliage on the rest of the plant is healthy and it's putting in new growth I don't think you have anything to worry about.

Another couple of tips with proteas - don't give them any fertiliser unless they look deprived (leaves yellowing) and don't hoe around them or do anything else that might damage the stem or root system. If you do decide to feed, use a light application of fertiliser with very low or no phosphorous, or a product formulated for phosphoroussensitive plants such as Osmocote for Native Gardens.

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