Hi Rose. You've landed on the Orchid Forum. People on a fruit tree forum(?) will be able to advise you. All the best with your plum tree. Whitecat8

I would put it in a basket with sphagnum moss.

Nick

Rose, the ideal time to do this is when the tree is is dormant, probably around september in your neck of the woods. Dig it up, getting as much of the roots as you can (granting that you'll probably have to sever a good number of bigger ones with a saw of some sort).

Plant it to the original depth (just a tiny big above where the roots meet the trunk), if not just a little bit higher because there will possibly be a bit of settling of the soil underneath.

Keep the tree supported with stakes for a year or two while the roots get established. Fertilizer this time of year and then once in the late summer will be beneficial in jumpstarting growth.

This spring take a shovel and dig around the tree, approximately one half the distance of what you would consider to be the entire root system. Root systems typically are the width of the limbs/foliage, just slightly beyond. Trees are smart enough to make sure their roots receive sufficient moisture to live.

During the spring and summer, the cut roots will multiply and branch. Come fall you will have much denser roots but much closer to the trunk and will not need as big a clump of soil to dig up.

This is the technique used by bonsai growers when they wish to start work on a tree that is growing in nature. They dig up the tree in the fall, move it to their property and replant it, usually in the ground, so they can start the long process.

Brooke

Brooke's got it!
Follow her advice.

Josh

I actually transplanted a medium sized fig tree using the above technique with an added twist. Dig out 1/2 of the root ball, cut it down to manageable size and build a wooden box around it. The tree lives of the undisturbed 1/2 while it grows into the box which is given plenty of water. 4 month later the other side was dug up and the tree was moved to the new location.

The landscaper who suggested this, claims you can reduce the size of the root ball by as much as 1/2 using this staged approach. The tree we moved was almost forklift size but 3 of us managed to drag it over to it's new location where it eventually rooted.

Nick