How to save dying Ericifolia banksias?

Rara1

Hello, 

Im hoping someone might have a reason for my dying plants…

i have two, two year old ericifolias turning up their toes. Dying from the inside out. I’m on South east coast NSW (they are endemic here), I built up the garden with native mix soil about 50cm before planting. I used weed mat as the garden that was there was a weed festival. 
In this same garden I have also lost a grevillia Dorothy Gordon and some isopogons. The soil underneath the built up garden is rocky and dark 😬

I have watered when it hasn’t rained, used only a little bit of native fertiliser. Does the dying from the inside help? Any knowledge would be appreciated. Thank you

EricL

Hello @Rara1 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about your banksias.

It sounds like your plants might be struggling due to drainage or root-related issues. The weed mat could be restricting airflow and trapping moisture, leading to root rot, especially since Melaleucas, Grevilleas, and Isopogons prefer free-draining soil. Your built-up garden soil over a rocky base may be creating a perched water table, where water sits above the hard layer, suffocating roots. 

The inside-out dieback could indicate fungal issues particularly if roots appear blackened or smell bad. To help, consider removing sections of the weed mat to improve air circulation, checking soil drainage by digging a small hole and observing water absorption, and forking the soil lightly to break up compaction. If root rot is present, trim affected roots and treat them with a fungicide like Yates Anti-Rot. A light application of liquid seaweed may also help restore soil health.

If you need further assistance, please let us know.

Eric