GROWING STREPTOCARPUS (Cape primrose)

10 deg C/50 deg F

The true species, of which there are about 100 in this genus, are rarely now grown as pot plants. An enormous amount of work has been done on hybridization and the production of variants by chemical and physical methods. and it is these exceedingly beautiful named forms that are at present so popular. There are also some superb strains offered by the leading seedsmen. However, streptocarpus are not the easiest plants to raise from seed without proper greenhouse conditions. For the home, it is better to buy young seedlings or plants, preferably when they are in bud or just coming into flower. These will be available from spring to summer according to the stage of advancement.

Established plants usually flower over a long period, extending from May to October, and often continuing well into winter. Streptocarpus belong to the same family as the African violet, and. ideally, rather similar cultural conditions are required. However, streptocarpus are less demanding with regard to winter warmth and strong plants will survive as low as 5-7 deg C (41 -45 deg F) if kept on the dry side during the winter. The

plants are also less demanding regarding humidity.

It is difficult to see how the common name arose, since the flowers are absolutely nothing like a primrose. They are rather trumpet-shaped and borne in groups on wiry stems well above the foliage. The plants send up these flowering stems in succession. There are large and small flowered forms, the latter types usually producing blooms more freely. There are numerous beautiful colours and colour combinations and there is often exotic markings and sometimes frilling of the petals. The John Innes Institute has done much work on the production of hybrids and there are many of them.

Unfortunately, the foliage of streptocarpus tends to be rather ungainly. It is slightly velvety in texture, very corrugated. elongated, curving downwards usually, and rather brittle so that it is easily damaged. Plants have to be moved with care and often it is wise to stand mature plants on a support so that the foliage can hang freely from the pot. These remarks may seem disparaging. but if the foliage is looked after it is not unattractive.

Good cultivars include ‘Constant Nymph’ (blue and purple flowers with dark throat veins). ‘Maasen’s White’

(white mutant of ‘Constant Nymph’). ‘Albatross’ (large-flowered mutant of ‘Massen’s White’ with a yellow eye). ‘Margaret’ (purple and blue new hybrid notable for almost continuous flowering), ‘Tina’ (pink and magenta, prettily veined, compact foliage). ‘Marie’ (rose-purple. white throat, nicely veined, very compact). ‘Fiona’ (lovely pink with waved petals). ‘Diana’ (cerise with white throat). ‘Paula’ (reddish-purple, pinkish centre, neat habit). ‘Karen’ (magenta and dark pink with darker veining). Streptocarpus grow well in any good potting compost, and usually a final pot size of 13cm (5in) is adequate. Water freely from spring to autumn, sparingly in winter, regulating the amount given according to temperature. Cave a moderately bright position, but avoid direct sunshine. The foliage can become very easily scorched and will then turn dark brown and unsightly. To ensure continuous flowering, promptly cut off faded flowers and remove stems when all the flowers supported have passed over.

Streptocarpus are most easily propagated by careful division of the roots in early spring. They can also be mutliplied from leaf cuttings taken from May to July. Cut a leaf into sections and insert in any of the usual rooting composts. New

plants will arise from the base. A temperature of about 18 deg C (65 deg F) is best for rooting, and the cuttings must be covered to maintain humidity. Established streptocarpus plants enjoy moderately airy conditions although the air should not be too dry. Aphids are the most common pest, and generally the plants have ’vv problems. It is surprising that streptocarpus are not more popular as houseplants. although they have long been highly prized for greenhouses and conservatories.

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