I offer this advice only with the disclaimer: your mileage may vary, because we don't have to overwinter ours here. But I have had friends tell me that this is how they do it in colder places. (These plants go dormant naturally in the winter, along with all the colocasias and xanthosomas, and re-emerge in spring here. The ground never freezes, so we get them back every Spring.)

I do grow the variegated form of Alocasia macrorhizza year round in a greenhouse. Its very large, because it never goes dormant, therefore it reproduces itself like a demon and has to be thinned every spring. I plant the thinnings outside. In my experience, macrorhizza does not form what I would call a "tuber". Its more like a "bulb".

ALocasias like Odora, Portodora, Calidora, Culculatta etc are more "tuber-forming" per-se, but to me, these are actually more "trunk forming". I have plants with trunks 2-3 ft tall.

The only ones that I think really form tubersthat kinda crawl over and under the ground are the Alocasias like Polly, loweii, sanderiana, etc and they have to get pretty large to have that.

Its really easy to overwinter macrorhizza if you take a tip from nature. Leave them outside until your nighttime temps force them into natural dormancy (the 40-50's range...maybe high 30's but not freezing). Once they go dormant, place the pot in a spot where it definitely won't freeze, and don't water it. In spring, move it back out once it warms up into the 50's and start watering it maybe once a week til the new growth starts up.

Its also possible to keep it indoors as a houseplant, if you have enough light. Just don't overwater it during the winter, and watch for pests.

I carry mine over in the greenhouse heated to 50 degrees, but I have some customers who have been growing the calidora as houseplants. Put it close to the window, don't water too much and watch for spider mites. Some of them don't even put them outdoors in the summer.

Its entirely possible to grow alocasia as long term houseplants. I have a couple that I have had in thehouse from day one, one is over 10 years old. I only put them outdoors if they get a pest infestation. I spray them with soap spray and put them out so natural predators can clean them up, then I bring them back in.

The keys to indoor success are, as sandy says, don't water too much, and give very good light. The ones I keep inside sit in front of a bank of floor to ceiling windows (24 ft across) and under 8 x 3 skylights (24 ft across). I also have palms and several other types of plants there...anthuriums, orchids, begonias...

Curious to note.

I have 3 upright EE's (Alocasia Mac) that I grew from bulbs this summer. I brought them inside when the temps started dropping and as an experiment I've placed them in 3 different spots with varying light.

The one getting the most sunlight is doing the worst. Oddly, the one getting almost no light is doing the best and growing rather quickly. The one getting medium light is doing OK too.

Same size pots. Only difference is the one in the sun gets a bit more water as the soil seems to dry more quickly than the others.

Thank you all! This was exactly what I came to this forum to find out! Great thread.