Hi. Early last summer, someone gave me about two dozen cuttings from their beautiful, vigorous heartleaf philodendron houseplant. I tried rooting these in water... very slow results (and I lost nearly half of the cuttings). Then I tried adding some willow-branch cuttings... slightly enhanced root formation, but still disappointing (some more cuttings gave up the ghost). So then (and by that point it's mid summer) I got a jar of gelled rooting-hormone, applied some to the cuttings, and planted them in a good potting mix. I planted these cuttings in an unglazed clay pot (about 1.25 litre volume of soil).

This did the trick, as most of the cuttings began to show good color and started to lengthen their shoots and grow new leaves by the early fall. I've got the pot in a south window, since our daylight hours are diminished (southern Canada). The vines did develop during the fall, and are still showing leaf development, albeit a little slowly because of dim and short daily sun. But the surviving vines (about ten of them) do look pretty good.

My question is: the pot is pretty small for ten vigorous vines, so it should probably be switched for a larger one with more potting mixture at some point. How can I tell when that is - how does one make a good guess with indoor vines? (I have not seen any root fibers through the drain hole in the bottom of the pot).

I'm pretty fearful of setting the plant back by removing the pretty-loose potting mixture and disturbing the forming roots. Thanks for any advice.

Joel