I potted mine just like a water lily. It wasn't very large either but put out lots of new growth after I put it in the pond and it didn't go dormant until the next summer. It did fine in the shade until my koi ate it, lol.

What do you mean by "the same as a water lily"? Judging by the few leaves left on the bulb when I received it (and the one reference that said plant it 1/2 inch to one inch deep), it looked as though the bulb was meant to be planted totally below the soil surface, whereas lilies need the crown above the soil surface. Oh well, I'll see?

Doubt if the "hardy calla lily" I bought will make it. Looked REAL bad when it arrived, in addition to also being being tiny. Tropical thalias and water sprite came in good shape though.

Well, I plant my water lilies with the top of the bulb/tuber sticking out of the soil. when I finish packing the soil, I add rocks and gravel to protect the tuber. Plant the Hawthorn the same because it is a lily type plant that is related to the water lily. You do know that it will go dormant in the heat of Summer, right?

Yup, know about the dormancy thing. That's why I figure I may not even know if it "survived" until fall. Funny though, I've read other blurbs from other sites/posts/etc where some people have had it not go dormant. Grain of salt.

Another "odd" thing I've read is advice for growing them says to STOP fertilizing them when they start going dormant - makes sense. Yet, other advice says to plant them in the same pot as a water lily 'cause when the lily is dormant the hawthorn will be growing and vice versa - seems to me you'd have conflict of interest regarding fertilizers in that scenario.