Freesias are tender perennials commonly grown in spring gardens and warm-climate winter gardens in U.S. Department of Agriculture Plant Hardiness Zones 1 through 9. Prized for their brightly coloured, funnel-shaped blooms and pleasant aroma, these flowers grown from bulbs or corms appear on only one side of a stem. Native to South Africa, freesias grow between 12 to 18 inches tall, making them suitable for flower bed borders and window boxes.
Loosen the top 6 to 8 inches of soil in a planting site that receives full sunlight for at least eight hours per day and has well-drained soil.
Add a 3-inch layer of organic compost to the planting site and mix it well with a tiller to improve the quality of the existing soil. Alternatively, add quality potting soil to a 6-inch-wide pot that has drainage holes.
Plant your freesia bulbs 5 inches deep in the prepared soil, with the flat side on the soil and the pointed tip facing upward. Space the bulbs 3 to 4 inches apart. If you're planting them in a pot, space the bulbs 2 inches apart. Tamp the surface of the soil with your hands to even it out.
Spread a 2-inch layer of mulch over the planting site to deter weeds and keep the freesia roots cool.
Water the planting site until the top 6 inches are evenly moist. For containers, stop irrigating when the water begins to seep out of the drainage holes.
Water the bulbs every five to seven days once new growth emerges, which usually takes 10 to 12 weeks. Use a garden hose to soak the soil to a depth of 3 inches. Once the foliage begins to die, reduce watering frequency to once every 10 days to two weeks.
Feed your freesias a well-balanced 10-10-10 fertiliser once each plant finishes blooming. You can use either a soluble bulb fertiliser or pellets that you spread at soil level and irrigate.
Leave the foliage on the plant to die back naturally at the end of the season. This allows the plant to keep absorbing energy from the sun to nourish the bulbs for the next season.
Freesias do not tolerate temperatures under -3.89 degrees Celsius. In areas with hard freezes, dig up the bulbs and cut back all the stems to 1 inch. Store the bulbs in peat, in a warm room with a temperature range between 75 to 85 degrees Fahrenheit until you plant them outdoors again in the spring. Plant the bulbs in the fall in areas with mild winters and no hard freezes, so they will bloom in spring. Spread mulch over the soil in case nights are exceptionally cold during that winter.