Can I use suckers as rootstock for grafting?

I’m pruning back an old apple tree that has some pretty big suckers. As I cut them off, some have roots on them and I’m wondering if anyone has experience (or thoughts) with propagating these into root stock that I could later use to graft desired cultivars to? And help would be appreciated.

Hello Leaf!

If the sucker is below the graft, it will be the original root stock and you should be able to grow more root stock plants from that cutting.  

If the sucker is below the graft, it will be the actual fruit tree and you should be able to grow more apple tree plants like the original from that cutting.  

Either way, if it is rooting, you can graft another apple to it. I would grow them on for a year to establish them independently first.

Before you put effort into this, do you know what the root stock is and are you happy with how it performs in your conditions? Most fruit trees where I am (UK) are sold on dwarfing rootstocks. Our garden has shallow soil on chalk, and my experience has been that dwarfing trees struggle. It is hard to buy standard root stock grafted trees, so I have a multiyear project on the go to make my own M25 rootstocks for future grafting work. I may be able to do my first grafts next year, all being well.