GENERAL CULTIVATION OF PRIMULAS
A good loam, with a little sand if it is heavy, or a little peat if it is poor, generally suits. Chalk is very frequently disliked by them, and a freshly limed is always risky. The ordinary primrose and polyanthus, however, suffer no ill effect from lime. A little peat moss litter may be useful. Larger growing types may benefit by an occasional surface mulch of well-rotted manure, and Primulas in pots may require a little charcoal to prevent sourness of the soil. All Primulas need plenty of water in summer, but in winter they resent excess, and can never flourish unless thoroughly good drainage removes all stagnant moisture from the soil. Hence with a clay subsoil it is well to have a crock drainage, ie. brick and broken clinkers, 16 or 20-in. deep, below the top 10 in. If the top soil itself is heavy, it may be lightened with gravel or sharp sand. Some Primulas even then show signs of winter rotting, and for them a protecting glass or overhanging stone is an advantage. The crowns must be examined after the frost, as they may need to be replanted firmly.
In summer, frequent hoeing, which conserves the water in the subsoil, will keep the ground cool and moist for the roots, and in long periods of drought, thorough watering to moisten the subsoil is essential. With regard to sunshine, about two hours a day on an average suits most Primulas, hence a westerly garden does better than a southerly, and wherever possible they should have dappled shade and sunshine, as in the shade of a Birch tree.
At the same time it might be noticed that the European groups of primulas are more prone to appreciate sun, while the Asiatic like a cool, moist soil and more shade. The Asiatic Group includes the well-known-like plants of the japonica, with purple-red flowers opening in June, the spike-flowered Primula libboniana with brilliant scarlet bracts and pale violet flowers, opening in August, Primula muscarioides, a Chinese species, whose purple blue flowers resemble Grape Hyacinths in growth. Primula sikkimensis, loose heads of scented yellow bells on powdered stems (reaches perfection at the bogside); and Primula Winterly large fringed lilac flowers, needs a cleft in a rockery where its roots can reach rich, moist, well-drained soil. This plant was found in the Himalayan heights by Captain Winter.
Of the European Group some good varieties are; Primula Allionii, a native of the Maritime Alps, with lovely pink flowers and small, sticky leaves (this should be firmly wedged in limestone soil, perfectly drained, and is propagated by pieces pulled off the crown); Primula Julice, wine-red, stemless flowers, very easily cultivated. The parent, in conjunction with the Common Primrose, of many profusely-flowering, longer-stalked hybrids; Primula marginata, lavender blue, leathery-leaved rosettes, easy to cultivate if planted in chinks and fissures of the, and not on the flat.
For 200 years this son of the “Bear’s Ear” of the European Alps has been grown in our English gardens, but it was not till working men of the north took up its culture, and the Auricula and Primula Societies were formed, that it attained its modern popularity. The original Alpine Auricula is a European plant with mealy leaves arranged in a rosette, and large heads of mealy-throated, golden-yellow flowers.
From this have been evolved varieties and hybrids in such numbers as to be impossible to include them, but there is no doubt that the old-fashioned Dusty Miller is a true descendant of the family, and its wine-red blossoms and broad white centre ring are still beloved of the cottage garden. Modern classification separates Auriculas into Alpine Auriculas, Show Auriculas, Selfs and Fancies, the three last being grown as pot plants in a cool house, while Alpine Auriculas find a home on the rock garden.
Alpine Auriculas are more vigorous than the greenhouse Show plants, and are not mealy. Thrum-eyed flowers, ie. those whose anthers are high in the tube, are considered the best to grow. They will grow in any good garden soil, but repay culture in a goodof loam, well-decayed manure, leaf-mould and sand.
Show Auriculas are green edged, white edged or grey edged. In the green edged, the flower is absolutely circular, the green rich and striking petals smooth edged, with the truss of bloom borne on a stout stalk. In the centre is a yellow eye, while inside the flower is a sort of paste of meal.
Like matter known as farina. In the white-edged, the farina closely covers the outside edge and completely hides the green, while the grey-edged varieties have edges but partially covered with the white meal, and so are dusty.
Selfs are a class in which body colour is carried through without any change, from the paste to the edge of the petal. They have naturally a thinner texture, but are frequently very lovely flowers.
Fancies mingle the characteristics of the groups, and are most popular among Auricula “fans,” who raise them from seed. Show Auricula and Fancy alike frequently have “snow-powdered” foliage with a silver edge, which adds to the quaintness of the whole plant.
PESTS AND TROUBLES AFFECTING PRIMULAS
Frosts will not harm Auriculas though it may spoil the bloom; damp during autumn and winter is their most deadly enemy. Hence no drip must be tolerated in the frames and no water must ever lodge in the heart of the plant. The pots need edge watering, not rose spraying.
If rot should attack the root, cut away the affected part and apply a little powdered charcoal. This generally induces recovery.
Green-fly above ground and Woolly Aphis underground are the Auricula’s chief pests. The Woolly Aphis attacks the roots and collar, and while fumigation may kill both, the plant may need to be dipped in insecticide to get rid of the aphides.
The grower seeking for a “new variety” must be careful to cross-fertilize from other plants of the same type, e.g. green edged with green edged, not with grey or fancy. Perfect blooms will then often be obtained.
Method of Cross-fertilization Remove the anthers from the flower selected as seedbearer, before the pollen is ripe. When the flower is fully open, dust the pollen from the other chosen flower on to the stigma.
The seed will ripen in July and can be sown at once, or in the spring. When it will germinate is another matter! Often seeds lie dormant for one or even two years, but patience will be rewarded in time, and as soon as theare large enough to handle they must be potted, using the compost recommended above for Alpine Auriculas, first singly into small pots, then larger as required. They should bloom in a 5-in. pot.
Another Method of Propagation is by taking offsets in February, those already rooted being planted in 3-in. pots with a little fibrous peat added to the compost. Those without roots soon form them if placed round the edge of pots. They will need more water in March, but must not be sodden, and need only be kept just above frost temperature. In April some protection from midday sun will be needed and abundance of air. The blooms then develop and may require support. The plants go out of bloom in May, and re-potting commences. During summer keep the plants clean, cool, and well drained. In September, exposure to air on all favourable occasions will strengthen the plants for the following year, and off-shoots should be removed. The secrets of success are: (1) A sweet, wholesome compost. (2) No stimulant, no artificial manures, no liquid (3) Utmost cleanliness. (4) Common sense about watering. Plants must never get dust-dry nor sodden. (5) No coddling.