I grow 2 different ones a elephant ear beside my pond I keep flooded in summertime& really takes off with cow manure and compost& another type i just call "wild taro" that grows in my pond and gets about 3 feet(no manure so probably why) ether way they are very heavy feeders.I know they can't be left inground outside of
zone 7(unless possibly keept dry)I'm not sure it would grow indoors in winter.I'm afraid it would act like my caladuims and would go dormant anyway.they like tons of water tons of fertilizer& love humidity.I grew up in TN and and my neighbor had them around her house which was brick.mom says they still grow.so when they go over to mow grass she will ask pearlie what she does with hers shes
zone 6 so would be close to your
zone.
are yours a tuber or the woody looking ball?woody ball will not do in pond directly,but tuber will.but they really like it warm out unlike my wild tarro.I'm
zone 8b but my elephant ear is not up yet but my wild taro is.now if we'd just stay in the 80s for good it would probaly wake up.
Hope i helped ya some