Funny you should mention propagating apple trees. No, I haven’t tried them yet. I just assumed the various commercial cultivars needed to be grafted on robust root stocks to thrive; kind of like hybrid teas. So I ordered up some mail order yellow delicious this spring for Cecropia food (a silk moth). Wouldn’t you know it, the bare root sticks were not grafted. If I knew that, I would have just tried to root cuttings myself and saved $10 a stick. Seems like half the hurdle in many things is just convincing yourself it’s possible in the first place!
I’ve propagated thousands of Arbs and many other plants with a homemade intermittent mister. It’s basically a 4’x8’ box with misting nozzles that keeps the cuttings from drying out or overheating. I’ve gone through many design iterations and have a design that works real well when we don’t get an extended heat wave up here (90+ temps). Of coarse that is about impossible to predict.
The biggest problem with cuttings is overheating, that is what the mist is for. The mist helps keep the cuttings cool(er) via evaporative cooling. However if it gets too hot outside, the mist just isn’t that effective and you get a soaked cutting bed (from too much misting). Soaked bed = fungus and death.
This year I’m going to move some of my propagation to the basement. :) That’s about the only way I know to make sure the cuttings don’t overheat while they’re trying to form roots. The cooler basement temps should require less mist which should keep fungus and mold growth down too. Generally softwood cuttings work best for deciduous trees. Some things root very fast, but trees generally take a while.