The more educated fruit growers will chime in, too, I hope, but I think you can do it, depending on how soon you are moving. It's the season for many types of grafts, but you would need rootstock to graft onto. You might still be able to order some rootstock. I would try to learn about stone fruit grafting online, and on this forum, and maybe others can recommend particular sites for the best information. You will have to plan ahead as far as when you are moving, and when you might be able to plant the new tree in your new location, or whether you will keep it in a pot, in which case you might want to graft on dwarfing rootstock. Mirabelles are truly miraculous (although you might have a Coe's Golden Drop possibly, or another--it seems to me all little yellow European plums are delish!). I never liked plums until I tried one! Good luck.

Thank you so much. What are the main sties that people buy rootstock from? I've never ordered any before, and I'd like to get the right thing, if I try! And I agree, if I can, I will do everything to make a cutting/graft work, but also ask the next owners if I can come back for another cutting in winter, as a backup!

Tough to root, the February scion cutting advise I like. Since you never have grafted before and you need to make this work without failure in one growing season, you might know someone who can help you with or
have a local nursery doing for you.

I don't know if this is a possibility but if it is a really old tree does anyone think it could be on its own roots? In which case if there are any suckers about they would be clones? Just a thought.

Make friends with the homeowners as suggested and meanwhile Google custom fruit tree grafting. Talk with the grafter you choose and ask when they would like you to send the dormant sticks/scions; and what caliper and length, and how many. You should be able to take it from here now.

Dax

Buy several healthy potted plum plants from local nursery/big box store. Get educated yourself by watching some Youtube videos for grafting and make try with confidence at those potted plants. You will see your success in few weeks.

Thanks everyone, for chiming in. I love the fact that I now have multiple options, with the ability to even choose all of them, if I want--including "farming out" the job of grafting it, as well as trying my own hand at it. Thanks, again for the great ideas. I never thought of paying someone to do a custom graft, nor buying my own rootstock at a big-box store by just getting a basic tree. Also, if the ancient tree is grafted, I certainly can't see it anywhere on the trunk--and I can usually spot a graft. But this tree is so gnarled that maybe it's long been invisible. But the tree also doesn't sucker. In all the years of living there, I've never seen one. I've found a few small trees nearby that may have come up from seed, and I'm keeping an eye on them, but I honestly can't even tell if they are the same as the Mother Tree. They look somewhat different, and they've neither flowered nor fruited, so maybe there's a cross-pollinator that means the tree doesn't come up true from seed, or maybe they are something else altogether. Whatever the case, I just don't want to say goodbye to this tree forever, so I am glad to have multiple options. The great likelihood is that I'll try several of them, and (If I'm lucky!) wind up with more than one successful clone--not a bad thing at all!!!

I've seen some golden gauge offspring/sucker trees look completely different than the adult when they are young. Sometimes they talk 6 years to fruit too. Might be better to choose a rootstock for the area you are in and graft over a few times in a few ways. I'm in a similar position too. I'e grafted to another couple trees, taken some scion wood and it's in the fridge. If the grafts don't take now, I'll bud graft in the summer to the rootstock I have coming soon. good luck

My golden gage is more egg like shaped :) Like a purple italian plum just golden and sweeter