Jennifer Schultz Nelson
Extension Educator, Horticulture
Most of us are familiar with calla lilies as cut flowers, but did you know they are a great summer bulb to plant in your garden or even in a container?
What is a summer bulb? Summer bulbs are summer-blooming plants that have some type of underground storage structure. Though called 'bulbs', they may or may not be a true bulb. In central Illinois, most summer bulbs are not cold hardy and will not survive the winter outside. These plants can either be treated as annuals, or may be dug at the end of the season and the storage structure kept indoors until the following planting season.
The plants commonly called calla lilies are members of the genus Zantedeschia. They are herbaceous flowering plants native to Africa, ranging from South Africa north to Malawi. Despite the name 'calla lily' these plants are not true lilies.
Calla lilies grow from a rhizome, much like how iris and cannas grow. They reach heights of 30 inches or more. Flowers are waxy, spathe or spade shaped, and cupped like a funnel. Colors are various shades of white, red, yellow and pink. The white flowers tend to be fragrant.
It is important to note that all parts of the calla lily are toxic. The roots are the most dangerous part of this plant. The plant produces oxalic acid, which if ingested produces symptoms such as: burning mouth and throat, swelling of the mouth and tongue, redness, swelling and pain of eyes, nausea and vomiting, and diarrhea.
While typically this reaction is not life threatening, it is possible to have a severe enough reaction to kill livestock or children. Use with caution near pets and children, and contact your local poison control center if plants are ingested.
Calla lilies prefer full sun to partial shade in evenly moist soil. They will even tolerate very wet soils, making them a great choice for along the edge of a pond. We are planting white calla lilies alongside red cannas on the bank of the pond in our backyard this year.
Plant the rhizomes which resemble small potatoes about an inch deep and one to two feet apart. The rhizomes may be started indoors to get a jump on the season. Calla lilies may also be grown in containers alongside other summer bulbs or plants.
If you wish to save the rhizomes from year to year, dig them in the fall after the foliage has withered. Allow the rhizomes to dry, and store them at 50 to 60 degrees Fahrenheit.
The hybridizing work of plant breeders has produced incredibly beautiful and unique calla lily cultivars such as:
'Black Pearl'-- flowers appear nearly black with maroon edges
'Captain Chelsea'®-- flowers brilliant yellow on exterior, rich purple-burgundy inside
'Edge of Night'-- deep purple flowers and stems, silver-flecked, purple-edged leaves
'Flame'-- yellow flowers edged in red become flame-red at maturity
'Hot Flashes'-- hot pink flowers with an ivory throat
'Peach Chiffon'-- light peach colored flowers edged in deep pink
'Crystal Blush'-- white flowers age to light pink
I am growing calla lilies for the first time this year-- near the pond, in my garden, and in a pot on my patio. If this is a successful endeavor, I think I will have a hard time fighting my 'plant collector' tendencies. There are so many beautiful cultivars available, it will be hard to grow just a few!