If you’ve ever visited the San Diego or San Francisco Botanical Garden you’ve no doubt marveled at the giant cala lily (Zantedeschia aethiopica) on display there.

The months of February through July bring out the plant’s best when it produces gargantuan white flowers on stalks that may grow to five feet in height.

Although it may seem that there isn’t a pot large enough to hold this giant calla lily, it actually adapts well to container growing.

Climate

Calla lilies do best in mild climates and the giant calla lilies are no exception. The plant requires cool weather to bloom but doesn’t tolerate frost so it’s best grown in U.S. Department of Agriculture plant hardiness zones 7 through 11 (enter your ZIP Code here to find your zone). This calla is a cool-weather bloomer, so don’t look for flowers in the summer.

Container and Soil

Plant the calla lily bulb in a 5-inch or 6-inch pot and use a combination of 2 parts of a well-draining potting soil mixed with 1 part of perlite or coarse sand.

Planting the Giant Calla Lily

Add two to three handfuls of soil to the pot and place the rhizome on top, vertically, with the growing point facing upward. Add enough additional potting soil so that, when planted, the tip of the calla lily’s rhizome sits 1 inch beneath the surface of the soil. Every time you re-pot the calla lily, bury the rhizome 1 inch deeper than previously planted.

Light and Moisture

These giant calla lilies require bright light but no direct sun. If you live in an area that receives winter frost, bring the pot indoors and keep as many leaves on the calla as possible.

Likewise, when the weather is hot, move the potted plant to a shadier spot and keep an eye on the soil’s moisture content. Giant calla lilies thrive even in boggy sites, so don’t allow the soil to dry out. Keep it consistently moist at all times.

Fertilizer Requirements

Surprisingly, you won’t need to apply a lot of fertilizer to grow the spectacularly large flowers these plants are loved for. At planting, mix 1 teaspoon of 15-3-15 into the planting soil in the planting pot. The high nitrogen content of this fertilizer helps the rhizome produce large, showy foliage.

Once the plant begins growing vigorously, begin fertilizing every month until bloom with a 5-10-5 fertilizer. Sprinkle 1/8 cup of the granules on the soil, 2 to 3 inches from the base of the calla lily and carefully scratch it into the potting mix. Stop fertilizing after the calla lily finishes flowering.

You will need to repeatedly up-pot the giant calla lily. Transplant it when the roots reach the bottom of the pot, using the next size larger container. Eventually, when the tuber reaches 6 inches, you’ll need a pot as large as 30 gallons or more.

Happy Growing!