I have a ten-year-old dwarf genetic peach in a large oak barrel. I want to relocate it while keeping it in the same container but it’s rooted into the ground. Should I cut off these roots or instead relocate them with the tree?
The simple answer is to cut off the roots that have grown into the ground at the soil line. But I have a couple of concerns.
Ten years is a long time to be in one container. It's probably very root bound, so you're going to need to prune the roots also. If left untouched, the peach will decline and eventually die from strangulation. Hopefully, the oak barrel is still in good shape, as you'll need to remove the peach from the container to prune the roots. I wouldn't be surprised that the barrel is deteriorating: hence, you may need a new container.
Root pruning makes gardeners very anxious, as they're concerned that something negative will happen when pruning the roots. The opposite is usually true, as plants benefit significantly from it. Its most significant benefit is that it allows you to keep a plant in the same size container indefinitely. November through March is the best months to root prune plants.
I'd tip the container over on its side to tug and pull at the fig until it comes free. Next, reduce the root ball's size by removing four to eight inches from the sides and six to ten inches from the bottom. You'll need to use a pruning saw, or you can hack away at the root ball with a shovel.
The peach is now replanted in the container, and you add new potting soil to fill in the void. In March, I'd reduce the top growth by a third in this case to compensate for the root loss.
Unfortunately, this will reduce the size of the crop. In the future, root prune every three to four years should keep the yield stable. My second concern is that you're going to need to change your watering frequency this year. Before, the fig was sustaining itself in between watering from the moisture in the ground. Now, all the roots are contained within the barrel, so you'll need to water more frequently. Every day with temperatures over seventy-five degrees should be the norm. And finally, don't forget the nutrients; two applications of Osmocote in March and July should do the trick.
NOTE: Genetic dwarf peaches and nectarines began with the Flory Peach (Note: they're now being called "Natural Dwarfs" - to distance them from current "GMO" concerns.) In the summer of 1939, an United States Army engineer was in northern China. He obtained several peach pits, which he brought to Modesto, California. In the early 1960s, fruit breeder Fred Anderson started making crosses with nectarines as well as did David Armstrong of Armstrong Nurseries. Mr. Anderson's hybrids were developed with Mr. Bob Ludekens of the L. E. Cooke Co. - (source LE Cooke) These trees are slow-growing, reaching a height of six to ten feet. They're more a compact bush than the typical tree. An independent garden center is your best source for these trees.