First off, Santa Rosa
is not uncommon; in fact you can often find it for sale in those tightly wrapped plastic bundles outside most grocery stores for the next 3 months - cheep. The HOS Rootstock available is "Citation," and "St. Julian GF-655-2;" I'm only familiar with the St. Julian
so shouldn't give a recommendation.
There should be a generous amount of Santa Rosa plum scions available at the Scion Exchange
, but if you're determined to clone this very
tree, act fast. I'd look the tree over for any pencil diameter shoots of "new growth" that haven't
begun to "push" yet. They'd be closer to the limb - the further away you get, the more growth hormone has arrived. There are secondary latent buds
on either side of the "main" bud. If you find any "tight wooded" shoots, it only takes 2 or 3, cut the entire piece and store it as described by others in your refrigerator. When anyone insists at the grafting table that we "just go for it," we can rub off the pushing buds, make the graft, and assume the secondary buds will do their thing (grow).
Lots of good questions: If you procured rootstock "this year" you'd best plant it out, you could pot it, but I don't see any advantages in that. And if you plant it out, you'll be making the graft yourself next year - a bit trickier on "stone fruit" than apples & pears...
... and I don't think anyone's ever done this: buy a "bagged" Santa Rosa plum from Bi-mart / Fred Meyer.., bring it to the Scion Exchange, choose a pollinator scion, bring it to (me)
the grafters and have us graft it to a limb of that young tree. - This is simply the way I do it any more, and only a suggestion - but good questions, and good luck!