Yes, Rapid Rooter works great and fit inside of dixie cups perfectly! I've also packed the cups tight with clean, quality potting soil only then pushed a hole into it with a nail (which I also use on every pellet to clean the hole for easy entry of the cutting) then used the cup just as I would a pellet. They don't grow quite as fast this way but is a quick fix for when you run out of Rapid Rooters (BTW, I also use a heavy dose of Clonex on each one). Cuttings I took 13 days ago are now growing through the Dixie cups that holds the Rapid Rooters in place (with a little soil) and I'll be spending the rest of the day potting 50-some clones...which I'm not looking forward to doing so I'm stalling by coming here to check on what's going on.