Freesias (Freesia spp.) are sweetly-scented members of the iris family native to southern Africa. In North America, freesias are hardy only in U.S. Department of Agriculture plant hardiness zones 9 and warmer. Elsewhere, they're grown as container plants or treated as tender summer bulbs, like gladioli. They're not difficult to keep from year to year, and the small effort needed is rewarded by larger corms and more flowers each year.
Growing Freesias Where They're Hardy
Freesias are planted in the fall in USDA zones 9 and 10, which encompasses southern Florida, parts of the Gulf Coast, much of California and Hawaii. In these areas, freesias bloom the following spring and survive in the ground year round. The individual plants are not large, so plant freesias in groups for best effect. Plant the bulblike corms 5 inches deep and 4 inches apart. After blooming, remove the faded flower stems and allow the foliage to wither naturally, as you would daffodils or crocus. Borrow a trick from commercial growers and plant an annual flower such as asters over them to hide the withering foliage and fill in the empty spot left after the freesias go dormant.
Growing Freesias as Summer Bulbs
In areas where freesias aren't hardy, plant them in the spring for summer bloom. Plant the corms 5 inches deep and 4 inches apart in generous groups. Allow the foliage to wither and die naturally, if possible. The corms are damaged at temperatures below -3.89 degrees Celsius, so dig them for storage as soon as frost occurs in your area.
Growing Freesias in Pots
Container-grown freesias flower about two months after planting. Plant the corms close together in a 5- or 6-inch pot; you'll be able to fit about six corms in pots that size. Cover the corms with 2 inches of rich potting soil and water only lightly until growth begins. Grow the plants in a warm location with bright light but no direct sun. Treat them as you would other houseplants, watering them when the soil dries slightly and feeding with a general houseplant fertiliser. Once the leaves begin to yellow, allow the soil in the pots to dry so the corms go dormant. You can either cure and store the bulbs, or place the pots on their sides in a cool spot until autumn, when you should repot the freesias in fresh soil for another flower display.
Freesia corms can be stored in the same manner as gladioli. Allow the corms and any soil clinging to them to dry for two to three weeks in a sheltered area, at temperatures between 15.6 and 21.1 degrees Celsius area. Once the corms are dry, gently rub off the soil. Remove any small bulblets, called cormels, that have formed along the bottom of the corm. These can be grown in containers until they reach blooming size in a year or two. Examine the corms for injury or disease, and discard any that are damaged. At the bottom of the corm you'll find a withered disc -- that represents the remains of the original corm planted in the spring. Carefully peel that away from the new corm and discard. Store freesia corms in labelled paper bags at 35 to 40 degrees Fahrenheit, such as in a refrigerator or unheated garage.