Growing Elephant Ears or Colocasia ‘Thailand Giant’ in a northern garden means you must have a bit of patience. This variety of colocasia can reach nine feet high with leaves that are four feet wide and five feet tall. However, I’ve found it takes almost all my northern garden growing season to develop the larger leaves. Thailand Giant made a great show in my September garden (see above and below). It is definitely possible to grow colocasia in your northern garden and bring it back year-after-year if you plan to overwinter the rhizome of the plant.
Colocasia are fast growers in tropical climates, hardy to Zone 8 (10°F), and adore warm humid weather. Water and heat are friends to the colocasia and encourage stronger growth. While sun needs are disputed, I’ve found Colocasia ‘Thailand Giant’ does well in part-shade to full-sun. Plant your colocasia after all danger of frost is done and you are experiencing warm evenings. Temperatures must remain above 50°F for Thailand Giant to find success in the beds. Thailand Giant does well in a “rain garden” or damp or wet area in the garden. Some ponders even plant the colocasia in shallow water.
Once planted, fertilize regularly with organic fertilizer. When the weather starts to cool, store the plant bareroot in your basement or a cool, dark storage area. Dig up before the first frost, wash off the soil, then store in peat moss. Colocasia ‘Thailand Giant’ can be started again in a container next to a bright or sunny window in order to kick start the planting season. Put out in the garden after temperatures warm-up again over 50°F in the early summer.