Cornus controversa 'variegata' cuttings

Hi everyone. I need advice.
I am trying to propagate this beautiful tree by hardwood cuttings. I took them after Christmas, from a healthy specimen at a local nursery-the manager gave permission. I used some vigorous watersprouts, as the regular branches seemed to put about 1/4 inch of growth on per year, and I couldn't figure out how to do the recommended 2-3 bud cuttings. The watersprouts had about a foot between buds, so mostly I did single bud cuttings, 2-4" long. I damaged the bark a bit with a knife, dipped in rooting hormone powder, then sank them in 1:1:1 mix of potting soil:perlite:pumice, in a 6" pot. I put a plastic bag over it, and put it on my open porch (facing north) on a heating mat. Now the buds are swelling!
I think it might be time to fertilize.
It might be time to pot them on.
I think they might need some light now. My choice is to use a plastic cold frame that has an automatic opener so it will not get too hot, with or without the plastic bag, or just put it out in the yard under a tree where it would get more light, but not be protected much. I don't think I can put the heat mat out in the rain. I live in a very mild climate, so if a hard freeze should occur, I can bring them inside, but it should not get much below 32 degrees from now on (crocuses are blooming, perennials are emerging).
What do you think?

MLM, I'd wait to pot them up when they exhibit new growth. There may not be roots yet...even though they are budding out.

How did it go? Are you enjoying new spring growth?

Dang. It didn't work. I gradually opened then removed the plastic bag, and gradually put them out in the sun and rain a bit, without the heat mat. Almost all of them leafed out, then withered, stopped growth, got moldy and died. I didn't know if it had been overheating from having plastic, or what. I pulled out the pathetic little twigs and they had not rooted. So this attempt was a bust, but I may try again.Of course there are about 20 variables to play with here.

I'm on a learning curve too, I found this really good info I thought I'd share with you:
http://www.ces.ncsu.edu/depts/hort/hil/hil-8702.html

Lurking.....cuz I want to learn vicariously! (Is that even logical to say? or is this what is meant by distance learning?)

Thanks for posting your question mlm, and thanks for the link Robin.

Lurkers always welcome Turtles, although you might be considered a participant since you commented. I always wanted to learn by osmosis...knowledge just falling from the air and being absorbed by my skin...effortless.

Hi I think if they have got roots which you find out by wiggling them--then they need to go out in pots with just a soil less potting mix. You need to water as it will be free draining but check the soil if its damp wait. don't put any covers over them if they have roots---they'll get rotten or moldy or shrivel and die.

Oh... also keep your pots in a shady area until they are growing more