I waited for more experienced gardeners to respond and none have, to date. If I had a large elephant ear bulb I would put it in fertile, fibrous, water retentive soil in a one gallon pot and move it to a 5 gallon pot after it is going good. I think it would do best when daytime temps. get to 80 degrees or more and was put in very bright light, or light shade, and out of strong winds. I do think they can take full sun if they are at a pond's edge but have only grown one or two in pots, years ago.

My grandmother-in-law used to grow tremendous size elephant ears, I've never seen them grow like hers. She planted some of them in ground, which did well, but left some in large pots to bring in her sitting room in the fall. The bulbs filled the pots. The plants were almost ceiling height, just tremendous. She used regular potting soil, often mixed with garden soil. I don't think she fertilized them or anything, just kept them watered well. I've grown them in the ground, they do moderately well even without regular watering. I've never gotten anything nearly the size she did though, but I think her bulbs were the type you are talking about, & mine just regular size.

Actually, I think the bulbs are of the taro plant, which the Hawaians use to make Poi. They are very poisonous, unless prepared properly. The plant does get ceiling high, at least.