Wire scars on the roots. There are ways to avoid them, but they make the wiring process more of a pain
Done properly, there are no wire scars on visible roots. No need to pad the wire using tubing, either. Everything is done under the soil level.
The exact technique varies a bit depending upon how many holes the pot has, and the position of the holes.
Assume a 4 hole pot, with the holes near the corners. Two wires are threaded up the holes. One on the left, and one on the right. So that there is a wire coming up from below in each hole. Position the tree in, then fold one wire down across the root ball. Let’s start with the front left wire. Fold it down, over the front edge of the roots, towards the front right wire. Twist the two wires together firmly. Then direct the front right wire to meet the rear right wire. Twist them together firmly. Then lay the right rear wire down against the rear of the rootball to meet the left rear wire. Twist together.
Now, you need to make a pigtail. Using a separate piece of wire, bend a hook into one end, and slip the hook under the front left wire near where it emerges from the bottom. Twist it so it’s securely attached. Now take it, and the wire from the back left, and twist them together about halfway in between them.
Now, here comes the secret technique! Grab the twisted two wires with you pliers, and while holdin the tree in position with one hand, pull on the wires with the pliers. The whole “cage” should tighten! Now, begin to twist the pliers to take up the slack, but release the pressure as you do. You’ll break thecwires if you don’t! So, it’s PULL to tighten, release pressure, and twist. You can do this several times. You can get that cage to tighten the root ball down very snug, Once it’s snug, go around and cut off loose ends, and tuck the wire ends down.
It should be tight enough so that you can lift the tree, and the pot stays firmly attached!
Now backfill with soil, and chopstick in...
When done, the “cage” is invisible, under the soil. No surface roots are damaged or need padding.
Of course, every tree is different, you may need to tuck a root under, or over the wires as you’re building the cage, or you may need to insert a chopstick into the rootball, and run the wire over the chopstick as you’re building the cage. It’s all engineering! (But not rocket science!)