A large genus of about 500 species. embracing the well-loved primrose and polyanthus. These plants in their modern forms make excellent pot plants for the home, even if only of a temporary nature. Several other species and cul-tivars or hybrids are also firm favourites. and are especially favoured for conservatory anddecoration as well as for window-sills. Very many species are used for alpine greenhouses. and some of these can also be grown on window-sills in cool, airy rooms. P. vulgaris is the common primrose, but this has been developed by plant breeders in recent years to produce plants of immense beauty anil in an exciting range of wonderful colours. These plants are quite hardy and excellent for the chilliest places in the home. They have now become popular pot plants, some strains tolerating gentle forcing so that they are in the shops just after Chirstmas.
The plants have the neat habit of the wild primrose, but theare very much bigger and borne usually in large. roundish heads. The colours include just about everything possible. There are rich reds, yellows, oranges, rose-pinks and creams and whites, and often there is a contrasting bright yellow eye. There are several strains of the P, hybrid type, such as ‘Formula’ (actually of Japanese origin). Tiniest Benary. especially suited to forcing, and ‘Mirella’. which is extra-dwarf. After (lowering, the plants can be put in an outdoor garden or given to a friend with a garden.These coloured primroses also make line window-box plants. Polyanthus are hybrids also derived from P. vulgaris, but are sometimes called P. v. chilior. Again there are numerous strains, the great heads of large being borne well above the foliage on strong . The F, hybrids have great vigour and strength and the colour range is wide. Most primulas have a scent, the intensity of which may vary according to type and growing
conditions. TheF, hybrid ‘Jumbo has an especially strong fragrance and the largest flowers of all. Most polyanthus can also be put in a garden after (lowering. and may continue to (lower and multiply each year.
The following primulas are tender and need a winter minimum of 5-7 deg C (41—f5°P). They usually come on to the market from February onwards, and are sown by nurseries from May to June. The earliest to Mower is P. praenitens (syn. P. sinensis), the Chinese primula, usually from February to March, but sometimes earlier. An old favourite is ‘Dazzler’, with brilliant vivid orange-scarlet blooms, but there is now an assortment of colours and variation in (lower shape. This species is a short-lived perennial, and is best discarded after flowering. P. ob-conica, also of Chinese origin, is a longer-lived perennial and can be kept for a number of years. It is remarkable for producing flowers nearly all the year round, and is an excellent houseplant. It is ;I species that is widely grown, and often offered for sale.
However, young plants flower more freely, and many people only grow it for a year or so. since it is easy to produce from seed. There are a number of named P, hybrids and other strains in a variety of splendid colours. The large flower heads are borne on strong stems well above the foliage. A word of warning: both P. praeriitens(syn. P. sinensis) and P. obvonica are liable to cause a painful. itchy, reddish skin rash on people allergic to them. The other primulas are very unlikely to cause skin irritation. P. malacoides, again from China, has earned the common name fairy primrose. because of its extremely dainty appearance. However, the flowers are borne in whorls, one above the other, on long stems rising above a rosette of dainty foliage, and the plant does not really have much resemblance to the common primrose.
It is a line spring-flowering pot plant, and there are a number of named strains with delicate colours. Although a perennial. it is rarely worthy saving and should be discarded after flowering. P.xkewensis can be saved and is a perennial hybrid, originating at the Royal Botanic Gardens. Kew. It has whorls of golden-yellow flowers, often sweetly fragrant, on long stems from winter to late spring. Theand often the stems and buds are covered with a whitish farina. All the primulas should be given a cool. shaded in the home, and kept moist. Plants rarely need -on unless they happen to be plants. P. malacoides grows well in 10cm (4in) . Peat-based composts are suitable, but if the plants are to be saved and grown on for more than a year – for example P. obconica and P. x kewensis—it is wise to water with clean rainwater. The plants do not like the alkaline conditions that may arise with the use of hard limy tap-water. The use of this may cause yellowing. and red spider mites can attack primulas, the latter should be especially checked for on polyanthus if they are being grown on from plants bought during the summer. If exposed to excessively low temperatures the tender species may have their damaged, and this is usually shown by blackening around the edges or sometimes by rotting brown patches on the leaves. This is most likely to occur if the plants are left on cold window-sills overnight where they may become frosted during winter or early spring.