I live in Cabo San Lucas, Mexico and I grow elephant ears outside. They are treated like all my other plants as far a water and fertilizer.
It depends on your area. I live in Southern Virginia and planted them around a stump I was trying to hide. I had put bricks around the stump and added dirt, fertilizer to about 6 inches deep. The spot got about 4 hours of direct afternoon sun but was otherwise in partial shade. I had mulched the garden as it is Hot and Dry here then watered on a weekly basis. They did well but I thought for sure I could leave them out in the ground over winter with heavy layer of mulch as they did get afternoon sun. I WAS WRONG they didn't come back the next year. Check and see what your growing zone is and then check to see if what the plants do best in. You will have to adjust your planting to the two. Your local garden center should be able to give you the best information for your area. If your not in an area where the plants will winter over you will have to dig them up in the fall, dry them (allow the greenery to die back) then keep in a cool, dark, dry place until spring when you can replant them.
Good luck :)
Here is a great video that is helpful: https://www.youtube.com/watch?v=T1n8wqu9xpc
since I don't know where you live, but as a houseplant, they grow great in just plain water.