O.K. I have done a VERY large amount of fretting over "rootless wonders" of the catt species! (Can we say root rot?) Select a smaller than you think they need pot. Nearly fill with your choice of potting medium. Stick a bamboo skewer (available at most supermarkets) firmly into the medium. Secure the Catt to the skewer with whatever it has in the way of roots just barely covered by the media. No roots, no problem! Just have the base of the catt setting on the top of the media. Make sure the catt doesn't shift around much- you may need more than one skewer per plant. I use twist ties/wire ties to wire the pbulbs to the supports. It seems to me that the catts won't form roots if they aren't fairly stable. I mist daily with a very weak solution of 7-7-7 fertilizer and water. Of the 50 or so rootless wonders I have been playing with, about 1/3 have not yet responded as well as I would like. (And two succumbed, poor things!).