With generous blooms and deep green, glossy foliage, Calla lilies provide an easy, showy display. The flowers now come in bright colors as well as creamy white, shooting up through the leaves on tubular stems. They have a rolled appearance, similar to the inside of a rose. They bloom throughout the year and when they're dormant, the foliage remains very attractive. Callas can grow inside or out, but they're sensitive to cold, so they're grown inside in places that experience freezing temperatures in the winter. They have few demands, but proper soil is one of them.
You may find callas already planted in pots, but if you order them through the mail, you will most likely get a bulb-like root, called a rhizome. Use any good potting mix, but make sure it is saturated with a great deal of moisture.
The best way to do this is to put the soil in a large bowl or tub and add warm water slowly. Potting soil is usually quite spongy and may not mix with the water well at first, so incorporate the water with your hands until the soil is very moist, but not dripping when you squeeze a handful in your fist. Fill your pot a little more than halfway with the treated mix and put the rhizome, pointed end up, on top. Cover the lily, add a little more water, and put it in a warm room.
Make sure the soil stays moist until a stem appears. At the first sign of a stem, put the pot in a sunny window, with a southern exposure if possible, The main soil requirement after callas begin to grow is that the soil stay moist. Unlike other houseplants, it's okay not to let your calla lily soil dry out between watering. In fact, callas flourish in soggy soil, and White Flower Farms, a grower of callas, recommends that you keep a saucer filled with water underneath the pot to keep it supplied with moisture at all times.
You'll see blooms between eight and 16 weeks after potting your Calla, according to how much sun is available. You will also see the plant visibly thickening at the base as well as growing taller. Despite the rapid growth, Pacific Callas recommends that you not fertilize your callas after blooms appear. Instead, add more good-quality soil to the pot until it is time to move to the next larger pot.
You may need to repot your calla as often as two or three times during the growing season. Move it to a slightly larger pot, adding water to the soil as you did when you first received your calla. Put a layer of saturated soil in the larger pot, then gently loosen the soil from the existing pot. Tap the bottom of the pot, nudging the plant out, rather than pulling your calla out by the leaves or stems. Place it in the larger pot, and fill around the sides with fresh, moist soil.
Warm spring and summer days allow your calla to grow extremely rapidly outside. Callas are a good solution for boggy, even swampy places where nothing else grows. Plant the rhizomes in any soil that stays uniformly moist and watch them flourish. You can also plant your previously potted callas outside in the summer, transferring them from the pot to a larger hole in the earth, and filling in with moist soil. Most gardeners even in temperate climates dig them up in the fall to spend the winter inside rather than risking possible damage from freezing and thawing.