Freesias are colourful, scentedon thin, wiry stems and are among the most beautiful of winter-flowering plants for the cool greenhouse. Anyone who has a greenhouse which can be heated enough to exclude frost and to maintain a temperature of 4 to 7°C. (40 to 45°F.) can grow these lovely flowers. Freesias have been developed considerably in recent years and strains can now be obtained in numerous shades, including yellow, white, orange, crimson and lavender.
There are two methods of growing freesias – from seed and from corms. But named varieties must be grown from corms.
Seven or eight corms can be placed in a 6-in. pot of John Innes No. 1 Potting Compost in August and covered with about 1 in. of compost. The pots are then placed in a cold frame under a thick covering of moist peat. This is to keep the corms cool and ensure that they will form a good root system. After a period of about six weeks the layer of peat can be removed and the pots taken from the frame and placed in a greenhouse which must be kept well ventilated.
Good strains of freesia seed are available in a mixture of lovely colours. Seedlings take about nine months to flower and if seed is sown in heat in February or March, flowers can be expected in time for Christmas. They need a temperature of 18°C. (65°F.) in which to germinate. Freesias are often sown and grown on to maturity in the same container. Boxes with a depth of 6 in. should be used for this purpose or about six seeds may be sown in a 6-in. pot. As germination is often erratic, some gardeners ‘chit’ the seed before sowing by mixing it with moist peat in a jar. Kept in a warm place there should soon be signs of germination and within a few days the seedlings can be spaced out in pots or boxes of John Innes No. 1 Potting Compost, taking care not to damage the young shoots or roots. During the summer the seedlings are best housed in a well-ventilated cold frame or they can be stood outside in a warm, sheltered place.
The compost in the boxes must never be allowed to dry out and ample water must be given in hot weather in the summer. In late summer feed once a week with a liquid or soluble fertiliser.
The seedling freesias must be taken into the greenhouse in September and their treatment then follows the same pattern as those started from corms. A temperature of 7°C. (45°F.) is adequate but a damp atmosphere must be avoided by careful ventilation. Less water is needed in the autumn and winter but when thebegins to become dry. Watering must be carried out.
Some support is needed to keep the foliage upright, and thin, twiggy sticks can be used for this purpose, placing them around the edge of the pot. Alternatively, insert three canes around the edge and loop raffia between them. Most of us would probably agree that the firstmentioned method is the least obtrusive, for the leaves and flower stems will soon hide the twigs.
When the flowers fade, continue to water the plants until the foliage shows signs of yellowing. Water supplies can then be reduced and the pots laid on their sides under the greenhouse staging. The corms must be kept dry in the summer while they are at rest but in August they can be removed from the pots and started into growth once more in fresh potting compost. Only the largest corms are likely to flower but the smaller ones can be grown separately to produce larger corms and these will eventually flower in a year or two.