Karri is one of my favorite trees, they're also one of the faster growing eucalypts so kinda perfect for this comp (although it remains to be seen if they're any good for bonsai...)
Seeds from nindethana, no pretreatment, decent germination
First seedling popping up (forgot to take a photo of the actual seeds):

After a few weeks:

Today:

I'll post an update once I've put some wire on these, I'm waiting until they're a bit bigger. Looking forward to seeing how these go
