I propagate dahlias using 4 oz cups for bottoms (with holes drilled) and 12 oz clear cups for tops to make little greenhouses. I dip my cuttings in rooting hormone and stick in really wet soil, the pop on the top. Takes about 2 weeks o r so to see roots in the bottom (also clear plastic cups) and you are off and running. It is almost too successful. I only do it on things that I hve one of and am afraid of losing. Never tried wood cuttings.