I’m going to go somewhere completely else and say that no matter what I’m bench grafting that arrives as bareroot (ornamentals/fruits/nuts/all deciduous) I treat them all the same.
When they arrive I put them in totes with shaved wood or a mixture such as promix and do it promptly and then put the totes on heat mats and cover everything with light poly. As soon as I see the bud scales splitting or a bit of leaf unfurling I begin grafting on them. Like I said it doesn’t matter what they are. I pull each rootstock out of the media and bench graft it with either a tool such as the omega or my knife. I have moist bath/beach towels laid flat on a table and after each graft is completed I roll it in the towel covering the roots completely and the graft union completely or the entire thing if it fits in the towel. Roll it over once and continue grafting and rolling one after another in that damp towel. I completely squeeze all the water I can from the towel so it’s damp/moist and not dripping wet. That’s how you want your towels to be.
You can keep rolled towels with grafts inside anywhere until you’re ready to put them onto heat mats, or if you have room on top of a heat mat immediately, place the rolled up towel inside a large garbage bag and set it on the heat mat. Come back in two weeks and check for callous. It’s very visible when the callous has been generated. If you don’t see adequate callous - then go ahead and give them another week. 3-weeks is all that should be necessary. You can put multiple rolled up towels in one garbage bag (that you sealed the end on when the grafts were placed on the heat mat - tied if off in other words but leaving a bit of an opening for air exchange.) That’s why a garbage bag works very well.
After callous, remove the grafts that did callous well back into your tote or totes so the roots are covered and back onto the heat mats the tote goes. At this point you should give the grafts as much light as possible in a spot where temps are between 45F to 85F. 55F is a pretty typical temperature for greenhouse grafters. 45 is on the low end but will work just fine.
Later when all spring frosts have passed you can either plant your new grafts in the ground or move them to containers.
The towel method is very similar to the use of a heat callousing bench/hot callous pipe. It’s the same principle.
Here are a few photos of what I do in my basement.
A couple bags of rootstocks. I take my pruners and cut them all to one height so they’ll be easy to cover in the totes.
Here’s a shot of after they’ve been chopped and dropped into a tote to next have a piece of poly draped over to warm them up. It will take 4-6 weeks for the buds to show signs of life at which point you will begin grafting.
The towel on the left I will roll the grafts up into.
When the grafts have calloused inside the rolled up towels they’ll go into totes and into as much light as possible as I said. I wax everything so the scions cannot dry out and/or use parafilm tape also covering the union area.
Here are the finished grafts now outside and all frosts have passed. For a few weeks or a month I use shade cloth. This is east facing. Then I remove the shade cloth completely. I don’t do it all at once. I wean them off the low light over the course of a week or 10-days putting the shade cloth up for a few hours the first few days then a few more hours the next days; then a few more hours than that the last days until the cloth is removed.
NOTE: last year I bought pine shavings in a cubic bundle from Walmart that are typically used for bedding for animals. It was a bad move because they held too much water. Years prior I used wood shavings that are thicker randomly sized pieces. Peat moss/Promix would work just as well as larger wood shavings. What I used were ground up pallets that my friend had a ginormous pile of given to him from his son-in-law that owns a pallet company.
EDIT MARCH 2017: Here’s a video showing what I discuss above:
Bench Grafting - Deciduous Material - Hot Callous Bench ‘Style’