Tips on propagating a dieffenbachia

I have a dieffenbachia (dumb cane) that was a gift from a coworker about 5 years ago. It was over 10 feet tall if you measured to tip of the highest leaf. I say "was" because I tried air layering for the first time and I guess I got carried away with my knife and cut too deep and... the cane snapped.

My heart stopped. Horror of horrors! I killed my favorite plant! Trying to avoid panic, I made a nicer cut at an angle, dipped it in Rootone, and repotted it in fresh potting soil. I read that this usually works but of course I was terrified. I kept the root part of the cane too, hoping it will sprout new growth.

Now I had about 6 feet of cane to work with. I grabbed all the pots I could find and sliced up the cane into sections about 3"-4" long, applied more Rootone, and placed them in the soil.

Being the perfectionist that I am, I want to know: Should I have used rooting medium rather than good ol' fashioned potting soil? Should I keep the sections dark until they sprout? How moist should I keep the soil? Would it help if I covered them with plastic wrap? How deep should I have buried them? (I made furrows about 1/4" - 1/2" deep.) What about the top? Does it need any special treatment (light, watering, humidity)?

If this works I'm gonna have about a zillion new dieffenbachias. I guess the folks here at DG get first pick!

(Also posted in the Indoor Plants forum.)

For my cuttings, I cut seections about 3" long, making sure there is at least one little notch band on the cutting.

I place mine on barely moist vermicultite , laying the cutting sideways and then cover with a piece of saran wrap and put a rubbe rband aroudn it to keep it on tight and just let sit in a semi sunny place. They need light, just not hot bright light.

I do touch them until I start to see a small green leaf popping up. Soon as I start to see the developemt of a leaf then I remove the plastic and just let grow until I see I got some stroong roots going, then they get repotted into small containers of potting soil.

Forgot to say that it takes them months to grow their roots and start a leaf nub , so have patience.