Why do the leaves on my grevillias have black spots and then go brown?

They are strong plants and are all 5 -6 years old. Last year I had one plant - pruned hard fertilized and cleaned around it. It grew back wonderfully well however this year I have 4 more plants with the same problem.

yates

06 September 2019 07:32 AM

Dear Lynley,

Grevillea grow best in a sunny/part sun position in the garden. They like excellent drainage and need to be fertilised with a fertiliser specifically formulated for native plants with a low or nil phosphorus level. Perhaps the area in which they are growing is not draining adequately and causing the plants problems. You may have to see if you can improve the drainage and at the same time keep them as healthy as possible so they can survive. Also check the plants for any insect attack such as scale. Do hope they improve.

Topics: Flowers and Ornamentals Issues: Diseases