It would help if you listed some of the plants you have attempted to root. Some plants do not do well with cuttings, or need some specific conditions to root. Some will take off like a shot. If you want an easy cuttings propagator, try pothos or heart leaf philodendron.

I never use rooting powder in my cuttings - I usually just use containers of water for my faster ones, or shallow pots of wet soil.

I have been rooting plants from cutting using the powder rooting hormone with good success. I managed to root Butterfly bushes, Hydrangeas, garden phlox, Weigela and Lilac Syringa.

My method is always locating the cutting in a shady area then cover it with any type of dome (see picture below) this is to maintain good amount of humidity at all time.
At the end, it takes three to four weeks for the cutting to root.
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