AusBonsai

I've dug a few plums in my time and the so called suckers make excellent bonsai. Dig in August in your part of the world for best success. After digging pot up and leave for a couple of years before doing any serious work on it. JMHO
Good luck.

Awesome, thanks for that. Do I have to do anything specific when cutting it from the main root? Or is it fine to chop wherever s'long as there's a decent amount of roots with it?

As far as I can see, the big one has heaps of it's own roots. But the real small ones haven't developed any of their own - they just seem to be growing solely out of the parent root.

Hi Rhi: sucker's or no suckers, they are all trees! if not done yet this one needs to be chopped like so as soon as it lose's its leaves. then in august as you see buds beginning to swell, you dig it up and chop it from the mother root, trying to get a few finer roots left on it. You wont need to many.

Hi Rhiannon, Ant is right prunus are sold all over Melb. bare rooted in winter so they take the rough treatment easily. They are also one of the few deciduous species which are able to be carved due to their very hard wood.
Craig

Cool. I need trees that can take rough treatment (read: able to survive my many mistakes made due to inexperience).

I did chop that one a while back, but not that far. I was too chicken to do it that far haha. I only did as far as one of the uppermost branches. Got a few new buds but it went to sleep before much else happened.

All the trees in the yard are dropping leaves now so I guess around now would be a good time.