AusBonsai

My brother gave this Banksia Praemorsa to me some years ago in a big air pruning pot. November last year (2022) I managed to get around to doing a first root work, and potted it down into a large but shallower depth pot.

It was a conservative root prune not getting too far into the core. I'd rather do it in stages slowly over a number of years, especially with species I'm not familiar with. Scraping the top down to the root base I am happy enough with how that's looking for now.

It bounced back no problems after this initial repot, which gives me confidence. Since then I've just been cutting and growing to push the growth back in closer to the trunk and create more density. The branches were long and most of the growth on the ends before.

It's getting nice and bushy now. I'll cut it back again shortly and choose a new trunk leader. Then I will focus again on trunk thickening while also starting to develop some main branches.
Before the first repot and root work Nov 2022
Root ball. The beauty of air pruning pots I didn't have to deal with a tangled mess.
Root/soil reduction
Potential front side 1
Potential front 2
Typical leaf size before any reduction
As is Dec 2023

Just performed a hard cut back. It gives me a good opportunity to see the trunk options a bit clearer now too.
Side 1
Side 2
Overhead

Unfortunately I have to report that this banksia died quite quickly coming out of summer. Classic dieback (phytophthora cinnamomi) symptoms. I am almost 100% sure it was due to overwatering with the heavily reduced foliage mass. I thought it was drying out but it was only the top couple of cm's and the bottom was staying too wet. I think this would have been better in a smaller pot that could dry out a lot faster.

Not to fear though I have another praemorsa on the go so I will just try and avoid the same mistakes with that one.

Patmet wrote: ↑April 16th, 2024, 12:52 pm I think this would have been better in a smaller pot that could dry out a lot faster.

Sorry to see this one give up but good to have you posting with a possible explanation of what to avoid in the future. I think you're probably right about the above, and this is not an issue exclusive to banksia ... something to consider for all trees really.
Glad to hear you have another one ready to step up and benefit from your experiences!

Ironically I think that's the leaf that's stylised on Dieback warning signs around SW WA. Or maybe not ironically, maybe it devastates Banksias.

I’ve reiterated that Banksia are not a tree you want to heavily reduce foliage with …. nor leave the roots wet or over potted.

The old adage of removing a lot of foliage on Bankisa when working them is an old wives tale.
It heavily stresses banksia, and combined with wet feet or low sun, it can easily kill Bankisa. I’ve lost a tonne more from root rot than drying out.

Thats a shame.

I’ve tried my hand at these too, but lost them.