Ken I am not sure if your asking me about the plugs but any way this is what we did, and how the tree planters do it here,
what I was using mine for was for mulching trees, and we had planted the trees, and then just ran the plastic over the trees,
the rider job was to mark or cut the mulch at the correct location, and then (think there is a picture of a person finishing the cut and pulling the tree up through the plastic, and placing a land scaping fabric staple at the cut to keep the wind from lifting the mulch,
I found that using a can of the marking paint was better than the cutting,
as if the person is doing the work is off, and many times even tho they only have about 16 to 18" to guess, some helpers were off by 8 to 10 inches, on the trees and then one had a hole and had to recut the opening correctly so I found that by giving the helper a can of marking paint to spray a dot where they perceived the tree to be, was better as most were fairly accurate but many times off, but if the dot was constantly off, it was very easy to find the tree and make a precise hole and pull up the tree and place the staples
(we cut and X at the tree, the fabric wears less on the tree than a single slot),
one other thing is by cutting the slit, every once in a while one will cut the tree off,
(I had this one person help me, and I instructed to take the utility knife and when you pass over the tree, stick the knife in and make a small slit, so I turn around to see on the first tree or to see if ever thing was clicking, we come up to the first tree, and he sicks the knife in the mulch and proceeds to cut a 6 foot long slit. so we tore that piece up and replaced it, and re instructed and it went fairly well.
so I suggest the spray paint, over trying to cut on the fly,. (the thing is he had seen some of the other tree planting that had all ready been done)
on any that needed replanting I made a auger out of a short section of 3" flighting from a old drill fill auger, and used the cordless 1/2 drill to drill and plant the replacement tree, worked well, through the hole in the mulch,
out of the 10+ miles of trees planted I had about 100 to replant mostly to to mice and moles, eating the roots, or stems, the trees I am thinking were ever 15 foot, and on the shrubs were ever 6 foot, the way I am remembering it was about 4000 trees, in the project,
one other thing (nature would have done this in time, but do to the wind we have I would take the tractor and then lift the machine off the ground and use the tractors tires to pack the edges down tight, (just straddling what we had just done),
below are two pictures of the tree planting and the planter I built