on the Colocasias. They like lots of water, humidity, warmth and good indirect light. Mine live outdoors all year, in shifting shade under my huge oak trees. If it gets cold enough they will die right back and stay dormant for a month or two. I cover them with mulch to keep them evenly moist and protect from frost. If they don't go dormant, they still slow down, the big leaves drop and they put out small leaves, slowly until the weather warms up.
Don't really know what they'd do indoors where it stays relatively warm all the time. But you'd sure have to keep them watered and if the light wasn't enough, they'd probably put up leaves with long, floppy stems. Most people on this forum who grow these up north let them die back in the fall and store over winter to use outdoors only.
Aiming to get them outside in May, for the summer? I'd think you could start them growing in mid- to late March indoors, to get a head start on the season. They'd be about ready to produce some nice big leaves by May.
Caladiums have a somewhat short season here, although a few of mine start up again in the late fall, after going dormant as soon as the weather cools and sometimes before that. I've heard you can prolong the life of the pretty leaves if you snip off the flower stalks before they open.
