HI all, After several attempts at finding planting and care information on the Mammoth elephant ear, I am asking here. I live in zone 9a and would like to know the proper planting time, care instructions, and most important, which side is the top on my bulb or tuber or whatever it is. Please and thank you.
Sounds like Colocasia gigantea or Colocasia esculenta, but that common name is used for a number of plants in the family Araceae; since you say you have a tuber, that would normally limit you to Colocasia or Alocasia. If your tuber is rounded, it's Colocasia, and if it's elongate, it's Alocasia. The top of your tuber is the lightly tapered part with the rings and lacking the hairlike structures; plant it as soon as the risk of frost has passed and water it when the soil is dry to the depth of your first knuckle.
Colocasia esculenta is highly variable and takes on many leaf shapes. Well over 100 forms are known. Most will survive winter as far north as zone 6 although they will go dormant during the cold. If it is an Alocasia, some species including Alocasia odora will survive in cool zones, but not all. These links may help: http://www.exoticrainforest.com/Colocasia esculenta large pc.html http://www.exoticrainforest.com/Natural variation within aroid and plant species.html http://www.exoticrainforest.com/Alocasia odora2 pc.html