There are a lot of things to address in this thread, and I'll start with a few.

First, you mentioned that your tree was planted at the wrong depth 13 years ago. DO NOT try to "correct" this now. ALL the damage that could be done by the improper planting is already done, and, the tree has adapted to the new soil level. When you transplant this tree, your goal should be for it to end up at the same depth as it currently is. You probably will want to plant the rootball a little higher to allow for settling, but that's it.

Without seeing the girdling roots, it's hard to give much advise about them. If you post some pictures, a more informed conversation about this subtopic may develop.

You may be able to get some idea about how large the rootball needs to be from this link: Generic Rootball Size Guide

Here is another guide that may give you some help with planting techniques: Planting a Tree or Shrub

guys with heavy equipment + limited or no knowledge of how to transplant larger trees = a disaster waiting to happen

guys with heavy equipment + experience and knowledge of how to transplant larger trees = a much safer situation

Thanks for the reply, Brandon. When you multiply by x to get the generic root ball size, what units are being used for the root ball? Inches seem small to me, feet large.

Of course I'm nervous about the idea of 'guys with heavy equipment + limited knowledge.' The tree company will be here just before, but they won't have digging equipment, just a 140 foot crane. We discussed trying to dig it up ourselves with shovels, but we figured the excavator would result in getting out a larger root ball. The owner of the septic company is a dad, and he 'gets it' about the tree and promised to do it himself. He's not just a dude messing around with his big equipment - he looked like he got a tear in his eye when we told him why we're so concerned about this tree. The plan is for my husband and I to be very involved, as well. I'm thinking about digging the sides and having the excavator get up under the tree. Gosh knows the excavator can handle the weight of a big root ball.

The website below suggested using river rock near the trunk of a tree planted too deep for air circulation. Seems like a lot of things I read suggest fixing depth problems when transplanting trees. Is this one of those hot button issues gardeners argue about?

Good point about needing pictures of the root issues. Once the tree is dug, I'll post pictures. For now, here in New Hampshire frosts are still a possibility, so I put the soil back in place. But if I'm keeping it at the same level, won't girdling roots just develop again?

Thanks, Trish

Here is a link that might be useful: Transplanting Trees

For rootball diameter, inches are used in the calculations. You can always go a little larger, but I think you'll find that the calculations will probably be pretty large for your tree. A four foot (48" in the case of a 4" diameter trunk) rootball is pretty massive, especially without power equipment.

I'm not especially impressed by the river rock idea for any case. But, especially in your case, it is not advisable since the tree would not benefit from a change in grade.

Just be careful about the heavy equipment. Good intentions (of the machine operator) will only go so far. I've seen plenty of trees killed by "caring" machine operators that weren't properly trained.

Trish, no matter what you do, girdling roots may reform. When roots are cut, new roots grow from just behind the cut, at roughly 90 degree angles to the root they deviate from. There's only just so much you can do about that.

Best thing is to try to get a decent-sized rootball with the move, take care of it thereafter, mainly by making sure it doesn't get real dry, and hope for the best.

+oM

P.S.

Girdling roots might develop, but most are a result of improper transplant work. Nurseries sometimes pot-up plants without properly addressing potbound roots. Homeowners (and professional landscapers) sometimes don't properly address improperly formed roots when trees are planted out. I would recommend addressing girdling roots in many (most?) cases, but it's not always possible/advisable/necessary.