Plum rootstock growth keeping it from fruiting?

I put a few plums into my garden a few years ago, mostly Mirabelle on dwarfing rootstock, and so far none of them have fruited.  One grows a thorny thicket every year around the trunk, that I cut back every couple of years, and last weekend I discovered that another was completely overshadowed by a thorny rootstock trunk.  

Both are cut back now.  Will they (continue to) sulk and not fruit?  Will this help?

Would fertilizing them this spring help kickstart them?  Any other suggestions?

Many thanks!

I had something similar happen on a peach tree of mine. It seems like a grafted trees will generally try to put its resources into growth from the rootstock area if it can.

I try to pinch off the growth really early if I see it, that way it will focus its resources into the grafted section. Pruning off large portions of the rootstock growth after they get big can encourage more vegetative growth in the tree and discourage fruiting. Fertilizer can do the same thing.

I've found that a good natural leaf mulch creates fertile, well balanced soil that encourages normal growth rates while also encouraging fruiting.

If you're ok with letting your tree grow taller, you can bury the graft, and the top growth variety will put out its own roots. I've done this on a lot of my fruit trees and have had good results with it so far.

Hope you get some plums soon Morfydd!

Steve Thorn wrote:I had something similar happen on a peach tree of mine. It seems like a grafted trees will generally try to put its resources into growth from the rootstock area if it can.

I try to pinch off the growth really early if I see it, that way it will focus its resources into the grafted section. Pruning off large portions of the rootstock growth after they get big can encourage more vegetative growth in the tree and discourage fruiting. Fertilizer can do the same thing.

I've found that a good natural leaf mulch creates fertile, well balanced soil that encourages normal growth rates while also encouraging fruiting.

If you're ok with letting your tree grow taller, you can bury the graft, and the top growth variety will put out its own roots. I've done this on a lot of my fruit trees and have had good results with it so far.

Hope you get some plums soon Morfydd!

Thank you, Steve!  I'm limited in how large my trees can get in my Kleingarten, so I'm reluctant to let the top growth go wild.  I may change my mind in a few years, though, bury the rootstock, and try to keep them in line with hard pruning.

My soil is fairly terrible, and I haven't fertilized these trees in years.  I'm emptying my compost piles this month (building new high raised beds) so I'm thinking I'll give all the trees a thin layer of compost and then some of my dried leaves - not yet leaf mulch but at least sat for one winter.

Fingers crossed!