I planted mine recently, although it'd probably be safer to wait until 5/15.
Regular garden soil is great, although I do hit everything with 20-20-20 fertilizer once in spring. Mine are happy in part sun and they have gorgeous pink blooms. If I had it to do over, I'd buy ones with spotted leaves so they'd look interesting even when they're not blooming.
Two things you need to know...cut the spent blooms when they start to develop seed pods. On my plants, this is obvious because the blooms get too heavy for the stems and they flop on the ground. Maybe you could eventually get new plants from the seeds, but it's quicker/easier to let the plant's energy go to the roots so they multiply and you get new plants from them. Sort of like what we do with daffodil bulbs.
Second, they won't survive a zone 5 winter. Dig them up around October. It's easy. They have shallow roots. For every round root you planted, there should be 2 or 3 roots, all attached together, to dig up. I just knock the dirt off, as much as possible, and pop them in a labeled paper grocery bag. Store them where they won't freeze over winter (I have a little unheated room off my garage). Next spring, you'll have extras to give away or trade.

I am assuming that one can also do this with potted plants. Our daughter in law gave us a lovely calla for Easter. It is still blooming. I was thinking of planting it in the garden until the fall, and hoped that it would re-bloom next year ( in the summer ). They are far better than the typical easter lily which lasts only for a week or so, and if planted in the garden attracts those horrible red beetles.

John

That should work, Jroot. Mine started out as a potted plant.

I have calla that I grow in pots in regular soil, in my pond over Summer. And every year I have double the bulbs, I leave it in pot over winter in the garage(Garage doesn't freeze). In spring the pot are full of bulbs. I have the white, pink and spotted leaves, which is another pink.
Karen, if your interested in the spotted leaves one, I will have some in the fall. You can contact me if interested.
Jroot, I have that problem with the beetles, any good way to get rid of them? I'm squishing them right now, but they are taking over.

Bern, I have had some success using Neem Oil (the pure extract) in spring at the first sign of the red lily beetles. I ordered it from Gardenimport, and also from Vesseys, in small plastic bottles of 50 ml. You mix 2 tsp neem, 1 tsp safer's soap in a litre of warm water, and spray the plants thoroughly. Do this as early as possible in the morning, or in the evening, to be on the safe side, as I have recently been advised that neem can be toxic to bees.
Judith

I keep the red lily beetle under control by spraying the nibs of ht elilies just as they are coming up in the spring, and the surrounding earth, with a 10% solution of household ammonia. It does not hurt the plants, but kills off the eggs of the beetle which live in the earth over winter. You may have a few, but they are manageable. Then be on the lookout in late summer for the larvae which they lay in large deposits of black 'goop' on the underside of the leaves. Just run your hand up the stem and wipe off the 'goop'. Learnt this tip at a horticultural show at a local college and it has worked for me.

Sounds like a good tip, norther_on. Thanks.

I'm a bit late in replying, but want to say thank you Judith and Northerner for the info on the red beetles. Will try it.