I'm not growing other Z. aethiopicas, so I have nothing to compare it to. However, my big plant does seem to have increased in size considerably, over the last 2 1/2 months of winter. Compare the size below, realizing the 1 gallon pots should stay the same. The bulbils have also been growing rapidly, once they break dormancy. I think it's Kartuz' site that says that the plant grows bigger in the Bay Area than elsewhere? If so, our cool nights are no doubt a factor. (Answer: Yes, but the comparison was to Southern California. However, their climate is most similar to ours. See link at bottom). I use a mix of "potting soil" and perlite, roughly 50:50 for most plants. I grow a lot of cloud forest plants, and they like constant moisture without being soggy. This works for most, and avoids any possible problems one might experience with a compacted soil that you mention. I forgot to mention that my plant outside is in a fairly shaded region, that gets some dappled sun, mostly in the morning. Here is a link that might be useful: Kartuz comments on giant Calla Lilies

If you have the type of refrigerator that gets hot on top put the pot on the refrigerator. Or if it blows hot air out at the bottom grille put it in front of the grille. Anyplace that is nice and warm. Your sunny window probally gets really cold at night so at least move it out of the window at night.

Hi cliff, try Plant Delights.john Here is a link that might be useful: plant delights

It's really silly to argue with the success of someone growing a palnt a world away from it's natural habitat. Here in Dallas, aethiopicas do extremely well as a winter houseplants with an eastern exposure. A SW exposure will surely scortch, if not BBQ them behind glass on a sunny winter afternoon. In your situation, I would not try to force them into dormancy "because they're supposed to" unless they stop growing or refuse to flower. Keiko