Where to Grow an Elephant Ear: Sun, Heat, Wind and Winter

How to tell it from an alocasia at a glance

Both are sold as elephant ears and they want opposite things, so it is worth being certain which you have before you choose a spot. Look at how the leaf is held. A colocasia leaf points down: the stalk joins the blade some way in from the notch, the leaf hangs like a shield or an upturned umbrella, and the tip aims at the ground. An alocasia leaf points up and out, with the stalk joining at the very edge of the notch and the tip held forward.

The rest follows from that. Colocasia is the one that will stand in water, wants full sun and heat, grows fast, and dies down to a corm for winter. Alocasia wants bright indirect light, resents wet feet and is fussier about cold. If you treat a colocasia like an alocasia you get a small, slow plant that keeps wilting. If you treat an alocasia like a colocasia you rot it.

Light: more sun than you expect

Given roots that are never short of water, a colocasia takes full sun and repays it with far bigger leaves and much stronger stalks than it makes in shade. Six or more hours of direct sun outdoors is not too much in a temperate summer. The dark-leaved forms in particular need that light to hold their color, and go a muddy green in shade.

The catch is that sun and dry roots together are lethal to the leaves. If you cannot keep the pot standing in water or water twice a day in a heatwave, put it where it gets full morning sun and shade from about two in the afternoon. That position gives you nearly all of the growth with a fraction of the wilting.

Heat is the engine

This is a plant that does nothing much until it is genuinely warm and then grows explosively. Below about 64F (18C) it more or less idles. Above 77F (25C) with water and feed it can push a new leaf every seven to ten days, and a corm planted in late spring can be shoulder height by the end of summer. If your plant seems disappointing in early summer, the answer is almost always that it is simply not warm enough yet.

At the other end, growth stops below about 59F (15C) and cold damage starts around 50F (10C). Frost turns the leaves to blackened rags overnight. That does not necessarily kill the plant, because the corm below ground often survives a light frost, but the season is over the moment it happens.

A pot standing on a paved terrace or against a sunny wall runs several degrees warmer than one on open ground, and colocasia notices. Warm hard surfaces are one of the cheapest ways to get a bigger plant in a cool summer.

Wind is the thing that ruins them

Nothing wrecks the look of an elephant ear faster than wind. The leaf is a large thin sail on a soft stalk, and a windy site leaves you with split blades, torn margins and stalks bent at right angles. Unlike a wilt, this damage does not recover. The leaf stays torn until you cut it off.

Site it against a wall, a fence, a hedge or in the lee of larger planting, where it gets its light from above and from one side rather than sitting in an open, exposed position. In containers, weight matters too: a tall plant in a light plastic pot blows over repeatedly. Use a heavy pot, or drop the plastic pot inside a heavier outer one.

1. Find the sheltered side Watch which way the leaves stream on a breezy day and move the pot to the far side of a wall or hedge from that direction. One move of six feet (2 m) often removes most of the damage.
2. Weight the base Stand the growing pot inside a heavier glazed or concrete outer pot, or put bricks in the bottom of the container. A blown-over colocasia usually snaps two or three stalks at the base.
3. Cut torn leaves off cleanly Once a leaf is badly split it will not repair and it is only shading the crown. Cut the stalk off close to the base with a clean blade and let the plant put its energy into the next one.

Moving it through the year

Placement is not one decision. In most climates the plant moves at least twice a year, and the two moves are the ones that decide whether you still have it the following summer.

In spring, do not rush it outside. Wait until nights are reliably above 54F (12C), then harden it off over a week rather than putting it straight into full sun, or the first leaves scorch. In autumn, bring it in or lift the corm before the first frost rather than after it. A plant that has been frosted can still be saved, but it goes into storage in far worse condition than one lifted while it is still green.

Record the two move dates each year alongside the night temperatures at the time. After two seasons you will be moving the plant on evidence from your own garden rather than guessing, and you will stop losing the last three weeks of growth to caution or the whole corm to delay.