For sheer elegance, I believe callas are unsurpassed. Their simple, exotic shape makes them favorites of flower arrangers. But they are so easy to grow you don't have to be a florist to enjoy them.
Callas (Zantedeschia spp.), sometimes called "calla lilies", are not true lilies but are aroids, members of the Araceae family along with anthurium, pothos, monstera, philodendron, caladium and jack-in-the-pulpit. Many aroids are native to the tropics. Callas are native to southern Africa. They are cold-hardy in the United States from USDA climate zone 8 through 11. Those who live in cooler regions can grow them successfully in container gardens, lifting and storing the rhizomes over winter.
Those structures often referred to as flowers are not actually flowers at all, but are modified leaves called spathes. The actual flowers are much smaller and are surrounded by the spathes. Callas are available in a wide range of colors. The glossy green foliage is very attractive and may be used in floral arrangements along with the spathes.
Callas are grown from rhizomes. A rhizome is a thick stem that grows horizontally at or just below the soil surface. The stem is segmented by nodes. Roots grow from the bottom of the rhizome. Shoots and leaves may appear along the top and sides of the rhizome.
If planting in the garden, select a site in full sun with richly organic, moist but well-drained soil. Some callas do well in wet, boggy soils, but never in standing water. Soil pH should be between 6.0 to 6.5. The best way to determine if the pH is within that range and contains the proper nutrients for callas is to have the soil tested. Your local Cooperative Agricultural Extension Service can help you. You can collect the soil sample yourself. For a nominal fee, they will send your soil sample to a laboratory for analysis. Be sure to call the Extension office for instructions.
Prior to receiving your rhizomes, cultivate the soil to the depth of one foot if the site is not boggy and add plenty of well-rotted compost. Remove weeds. Soil test results may recommend other soil amendments. Follow those instructions. The soil amendments you may use depends upon the type of soil you are in need of amending. Common soil amendments include sulphur for lowering pH, limestone for raising pH, sand for helping drainage, clay for slowing drainage, gypsum for breaking up caking clay and compost for enriching the soil. Bone meal is especially good for calla rhizomes. Which you should use depends upon your particular circumstance. If you use synthetic fertilizer, allow at least a week before planting so it can be incorporated into the soil by rain or irrigation and not burn the bulbs. The site should be ready for planting when your callas arrive.
Bear in mind that all parts of the plant are toxic if eaten and can cause skin irritations and/or allergic reactions in sensitive persons. If you believe you might be susceptible, wear gloves when handling any part of the plant.
Calla rhizomes can be planted in fall or early winter in warm climate zones, or in spring. If planting in spring, do so when the soil has warmed and danger of severe frost is past. They should be planted shallowly with the tops exposed, similar to German iris. To determine which is the top side, hold the rhizome horizontally and look for small buds or growing points. These growing points are called "eyes." They resemble the eyes on potatoes. The area with the most eyes is the top side. In a hole or trench, lay the rhizomes horizontally with the eyes looking upward. Space them at approximately twelve to eighteen inches apart. Press the soil around them leaving a portion of the rhizome exposed. Water well. If some of the soil washes away, replace it. With warm soil, roots and shoots should begin to form soon. A light layer of straw mulch will help to preserve moisture and suppress weeds.
During summer, you may fertilize occasionally. Apply 2 tablespoons of 10-10-10 fertilizer per ten square feet of garden area every two weeks until spathes appear. Do not allow synthetic fertilizers to come into contact with the plants. Irrigate if rainfall is inadequate. Soil should be constantly moist (not soggy) and never allowed to dry. Weed when necessary, but be careful not to disturb the rhizomes. Occasional application of a recommended insecticide will keep leaf-eating insects away, though the extent of their damage is usually minimal and cosmetic. Call your Cooperative Agricultural Extension Office for insecticide recommendations. Always, follow label instructions.
Growing callas in containers is not much different than in the garden. Use the finest potting soil; cheap soil will give poor results. The best potting soils will be light-weight, peat-based with added materials to enhance plant growth. Select containers that will accommodate the calla rhizomes and any other suitable companion plants. All companion plants should have similar soil and moisture requirements. Because container gardens can dry quickly, take steps to keep the pots properly watered. Adding moisture retentive gel to the soil can be beneficial. Larger containers are not as susceptible to drying. Tipping over can also be a problem with small containers.
When the spathes appear, you can cut all you want for flower arrangements. Harvest in the morning or evening when temperatures are lower. Use sharp clippers or shears to make clean cuts. Immediately place the cut ends of the stems in a bucket of cool water. The cut "flowers" are long-lasting.
When bloom time is over, let the foliage remain to build reserves in the rhizomes for the next growing season. Continue to provide water sufficient to maintain moist soil. You may remove the foliage when it has turned yellow.
If you live in a climate zone where callas are not cold hardy, you may dig and store them until the next growing season. After digging them, remove foliage, wash the rhizomes and let them dry in the shade. Do not let them become shrivelled. Pack in peat moss and store in boxes or bags with some ventilation. Plastic bags with ventilation holes like potatoes come in will do nicely. Store in a dark place where the temperature can be maintained between 45 and 55 degrees F. Moisture should not collect in the storage container. Neither should the rhizomes be allowed to dry out.
Return to Callas at goGardenNow.com.