How to Grow Calla Lilies Outdoors

Choose a partially sunny location for the best growth of calla lilies. Morning sun and dappled noon light provide ideal conditions. Mix in 3 inches of compost and 2 inches of sand to a 2-foot-by-2-foot area. This will ensure that the plant's roots when they grow will have well-drained soil and organic nutrients.

Dig a hole 4 to 6 inches deep and plant the rhizomes with the growing eyes up. These are the bumps on the rhizome. Place the rhizomes 1 to 2 feet apart. Fill around them with soil, press firmly and water until puddles form on the surface of the soil.

Fertilize after the shoots have risen 5 inches from the soil. Use a granular fertilizer and mix 1/2 cup into the soil around the base of the plants. Don't get fertilizer on the shoots. If you do, rinse it off to prevent foliage burn. Water after fertilizing.

Keep the calla lily evenly moist. This may mean watering at least twice per week in the summer. The soil should be damp, not soggy and muddy. Watch for slug activity. If the leaves are getting eaten, apply a slug bait around the plant.

Prune out the spent flowers as they occur, but keep the foliage until late fall so the plants can gather energy to store in the rhizomes for spring growth. Once the foliage is yellow and dying, you can cut it off at the ground.

Remove the rhizomes for cold-weather storage. Calla lilies are adversely affected when temperatures dip below 25 degrees. Dig out the rhizomes and allow them to dry for a day so you can brush off the excess soil. Trim any greenery left and wrap them in peat moss inside a paper bag. Store them in temperatures of 50 to 60 degrees Fahrenheit in a dry, dark area until spring.