I might be wrong but I had always assumed that if the grafted root stock started to send out sprouts that in time it would eventually take over the entire tree.

If you could keep the rootstock sprout under control (pruning), it might not "hurt" the graft much. But you'd have to prune it carefully to have it flowering but still under control.

Any neighbors nearby with fruit trees?

There are so many apple trees in my town, it's never a problem.

That makes me wonder, will root stock bloom at the same time as graft?

I wonder that too Bill.

And no one has fruit trees around here

Just buy yourself a flowering crab tree.

One that blooms around the same time as your apple.

I don't know about pears so can't help you there.

bill

You could graft multiple varieties onto your tree. Orchardists do this all the time to improve pollination; you have to graft a type that easily distinguished from the main variety.

Sure, that could be a possibility too, if the OP knows what their rootstock is. Knowing the compatibility of the rootstock to scion is very important to successful grafting.

I wonder a bit about why the apple tree is in the greenhouse. Unless it's a really big house, it's probably a fairly small tree. In my own experience of using small greenhouse action, stuff can be bumped up by a week or two. I wonder if the OP just moved the tree out of the greenhouse if that would make it pop a bit later and in line with the crabapples.

David Gray, yes. they sell 5 in 1 grafted pear trees -- I have one. Planted on my stream bank. then flooding undermined it and it fell into the stream, but some roots remain intact and it still grows a bit lying down and still holds the bank somewhat. The rootstock part is the only surviving part, and guess what it is.... Bradford pear!

Lol bengz... you wear hipwaders to harvest that thing?

bees, there's nothing left alive except the Bradford pear rootstock. Interesting that the Bradford rootstock was much more than just a base, but actually a long central "tree" with the grafts in sequence along it. Subsequent flooding has pushed the remains parallel against the bank on which it is still attached. Just upstream from there you can see the remains of a planted bankside weeping willow that had its trunk and roots exposed by erosion but is still barely alive and holding a small amount of bank together.

Ive got the apple inside the greenhouse because it does so much better and makes huge, delicious apples in there and not so much outside

So for the pears I resorted to breaking off pieces of a callery or bradford … whatever, pear across town and pollinating my pears by hand lol. I was actually pretty successful.

L Clark, that's pretty cool. You might just cut off a blooming limb of Bradford pear and put the bottom of the stem in a jar/bottle of water right beside your pear, and the bees/etc would do the cross-pollinating work.