Elephant ear bulbs are tropical and sub-tropical plants and can be grown
year round in USDA gardening zones 8-10 where the foliage will die down
to disappear during the low-light winter months.
I've read reports saying a very deep mulch will bring them through a winter in zone 7 if the winter is not severe. In colder garden zones, the tuber must be dug and stored over the winter. While the plant can be grown in the ground or in large containers the recipe for success is warmth. This is one plant that simply does not grow well in cool temperatures.
I note that this plant is really Colocasia esculenta and is grown in tropical areas for the starchy tuber used in cooking.
Elephant ears or Colocasia esculenta 'Black Magic'
Plant after all danger of frost has gone. Dont try to cheat it a little or the cool temperatures will rot out the tuber.
Plant in the shade. A little sun isnt going to hurt too much but the best results will be had in part-shade gardens. In northern gardens, more sun is acceptable when compared to southerly gardens.
Plant with the blunt end pointing down and plant shallowly so the top of the bulb is 2 inches below the soil surface.
Water thoroughly with warm water (never use cold water on this plant).
Wait 2 weeks, you should have good growth in this time (maybe as long as 3 weeks).
It is a good idea to have several inches of organic mulch on the soil surface to keep soil uniformly moist. An even supply of moisture will go a long way towards keeping elephant ear bulbs happy.
Plant them at least 3-feet from another plant. If grown properly, they will require every bit of this space.
Feed with compost when planted and once a week with fish emulsion after that.
Colocasia esculenta or Elephant Ear
This bulb will stop growing and start suffering as soon as the air temperatures go below 50F.
In the fall, when this starts to happen, dig up the Elephant ear bulbs, clean them off and allow to air dry indoors for a few days.
Then store cool (no frost) and dry until it is time to plant again next spring. Excess moisture in the air will lead to fungal problems attacking the tuber.