I have some David Austin roses that I have had in containers for a good 4 years now and the pots are not the biggest. They are pot bound and are not performing that great and their growth is quite stunted. I am moving house in a month or so and want to put them in the ground.
My question is will they be ok to be transferred to the ground and will they start to do really well and grow properly... Or is it best to start a fresh with new young roses that will grow straight into the ground?
You are not alone! I have probably close to a dozen roses I grew from cuttings that have been in pots for some years. In my experience, you should be able to transplant them to the ground and have them thrive.
Usually the best time to transplant is in the early fall or early spring. Before planting, water them well. Then remove the root ball from the pot and do your best to untangle as much of the root system as you can. Since it's likely that there will be roots break off, I usually trim the same amount from the top as there are broken roots (like if I lose/remove 25% of the roots, I prune 25-30% from the top growth (which I usually try to propagate into more plants). Since roots are constantly dying and regrowing, you don't need to untangle the whole root system, just enough to have some to spread out in the planting hole so they're growing away from the plant instead of circling it, like they do in the pot. As older roots die out and are replaced with new roots, the new ones should grow out, instead of around.
Despite their reputation for being finiky, many roses are actually quite durable, and can tolerate some abuse and neglect. I would totally try to transplant the ones you have before investing in new, younger plants. Even if you don't get a 100% success rate, at least you won't have to replace all of them. Good luck with the move and with the roses!