Growing Primulas

“A Primrose by the river’s brim, a yellow primrose was to him, and it was nothing more.” But to the gardener it is a humble member of a “far-flung empire” of plants whose flags wave on Alps, Carpathians and Rockies; from Northern Siberia to Tibet and the Himalayas, over Japan and Burma, and throughout Europe and the British Isles; whose denizens are at home on mountain ledges, in wooded valleys, and by steaming bogs; and whose ways of living are so various that a lifetime’s study can be given to it.

It is at first difficult to realize that the Irish Galligaskin or Jack-in-the-green (that curious primrose with a large Elizabethan ruff of leaves round its slender neck), the stiff early Victorian “Dusty Miller,” and the Primula Bulleyana (Candelabra section) with free, light graceful heads of starry flowers, all belong to one family.

Primulas are grouped popularly as “Primrose,” “Cowslip,” “Polyanthus” and “Auricula.” Those species, which belong to none of these four groups, are usually accorded their proper name of Primula.

Candelabra Primrose (identified by User:Steve ...

Candelabra Primrose (identified by User:Steve nova) (Photo credit: Wikipedia)

Primroses

This is the popular name for the common P. vulgaris which grows wild in our woods, and is the parent of a number of garden primroses, various in colour ranges. They include shades of pink, blue and mauve. The purple primrose P. Sibthorpii, which is a native of the Caucasus, is also thought to have contributed to the strain of garden hybrids, one of its probable descendants being a blue primrose with a yellow eye. This is of a generous habit—it flowers early and it flowers Jong, which makes it well worth a trial.

Other recommended varieties are: “Arthur de Moulin,” like a Parma Violet;”Salmonea,” soft rose; “Red Paddy,”compact crimson; “Quaker’s Bonnets,” a double lilac; “Burgundy,” clear purple; “Cloth of Gold,” ragged, but lovely; “Madame de Pompadour,” rich velvety red. Of the double class there are: The “Bonaccord Doubles” and the “Hose in Hose” varieties, “Lady Lettice” and “Ladies’ Favourite.” There are also the Double Polyanthus type represented by “Prince Silverwings,” a blue-purple, silver-laced flower, “Curiosity,” with three or four shades in one bloom, like coloured marble, and “Tortoisehell,” a rosette flower of orange and terra-cotta.

Primroses flourish in many soils, but like well-manured ground (bone-meal and leaf-mould added to the ground before planting), a sufficiency of water, a certain amount of shade and sun, deep, firm planting, as they are inclined to work up out of the ground (a top dressing of leaf-mould at times will help to counteract this tendency), and the picking off of dead flowers. Roots should be divided every two years.

It is now recognized that the Polyanthus, so popular for spring bedding, is a cross between the Common Primrose and the Cowslip (P. officinalis).

Like the Primrose, it has of late developed a whole range of colours, but double forms in bunches on a stalk proved too heavy, and are no longer sought.

The best known and finest strain is the Munstead strain, of forty years ago, merely white and yellow, now in the whole range of primrose colours. It has almost ousted the old florist’s Polyanthus, with its red or black petals, laced round the edges with gold, yellow eye, and other special markings.

The plants flourish in fairly moist soil and in partial shade. They are best divided every year. They can also be raised without difficulty from seed, and planted out 6-9 in. apart in July or August.

Almost all the remaining Primulas are looked upon as somewhat difficult to rear. This may be because they are foreign species that are unused to our climatic conditions. A plant from Siberia used to a long, cold winter rest, and a definite and steady change to heat and growth, is at a disadvantage in England, where spring days invade the winter months, and snow may fall even in June! Gardeners have to study the natural surroundings of any plant to make a success of its cultivation. Thus the rocky-ledge plant from the mountains would be put to the North side of a rockery, where the sun does not burn it, and the bog primula be set within easy reach of water.

There are, however, some general instructions as to propagation and cultivation that apply to the whole genus. As with many other plants, propagation may be effected in several ways: by seed, by root division, and by offsets. Seed is sown (a) indoors in pots and pans or (b) in the case of hardy Primulas such as the Candelabra and Sikkimensis groups, in a bed in the open, or in a cold frame.

INDOOR SOWING

Indoor sowing depends for its success on drainage, soil, method of sowing, and water. To secure good drainage there must be a drainage hole in pot or pan, and about a third of the pot space must be filled with broken crocks. Above this sphagnum moss or beech leaves are laid, to keep the drainage holes clear of soil. Above this is the soil, rough in the lower part and sifted to fine texture above.

The soil used is a compost of two parts good fibrous loam, two parts leaf-mould, and one part sand. It must be in such a condition as to form a bail when squeezed, but readily fall to pieces when touched or set down. The seeds must be sown very thinly and with only a fine layer of sand above them. Thickly-sown seedlings become spindly and weak, and if really well spaced, seedlings can be left undisturbed for much longer; a very important advantage.

It is better to water the soil after sowing, either by immersing the pot or pan in a basin of water up to the rim, and holding it there till percolation has taken place, or by watering with a fine-rosed can distributes the moisture more evenly and thoroughly, and is less disturbing to the seeds. When many seedlings are being raised, however, a fine rose will save much time.

After sowing, cover each pot with a pane of glass and a sheet of brown paper, or place in a frame or greenhouse. Wipe the glass every two or three days to remove moisture that has collected on the underside, and see that the soil does not become too dry.

OUTDOOR SOWING

Outdoor sowing of primulas is much the same.

A 6-9 in. layer of ashes in the bottom of the frame for drainage, then a 6 in. layer of mossy fibre and a 5-6 in. deep layer of the compost. Firm the surface, and sow evenly and thinly, either in drills or broadcast. Cover lightly, water with a fine rose, and close and shade the frame till germination occurs. See that there is plenty of water supplied to keep the soil steadily moist, as most primulas like a damp soil.

The best time for sowing in a greenhouse is a few weeks after the seed has ripened at the end of the summer. This gives a larger percentage of germination than spring sowing, but Primulas are peculiar in that a number of the seeds remain dormant the first year, and appear the second spring after sowing. Hence, if germination is poor the first year, keep the seed pan as it is till the second!

English: Fairhaven Water Gardens 2 A close up ...

English: Fairhaven Water Gardens 2 A close up of one of the Candelabra Primulas (Photo credit: Wikipedia)

For outdoor sowing March is the best month if a frame is being used, April if a shaded, open bed is made up. When seedlings appear, by gradual stages give light and air, never exposing them to full sunshine. Water regularly and watch for any sign of damping off. With the second pair of true leaves, seedlings are ready to be pricked out into boxes filled with the same compost as that in the seed bed. Disturb them as little as possible in the process and, unless they are tender varieties, put them out in the cold frame as soon as possible. They fail in warm greenhouse conditions, particularly in summer.

PROPAGATION BY DIVISION

Propagation by Division is easy, common, does not require much space, and ensures identical reproduction in colour, size and habit, but it is only possible when there are several crowns to one root system.

All perennial Primulas, including Polyanthus, Cowslips, and the common Primrose, which form several crowns or growing points, can be readily increased by division, but there are a few which, like P. Lilioniana and others in the Muscarioides section, do not form more than one growing point, and there are also some woody-stemmed species whose crowns are too firmly attached to be successfully separated.

Method of Division (1) Carefully lift the whole plant. (2) Either cut or break each crown gently from the main stock, bringing away with it a few roots. (3) Replant each crown separately. First make a good-sized hole, so that there is plenty of room for the roots; make the ground firm round it and water well. Shade with fir or spruce branches or some light covering, and water every day to keep the plant from withering. The plant should be well established before the winter frosts, hence July or August should be chosen for division, and preferably a damp day. Plants thrive better if moved into damp, warm quarters, and roots are still active at that time of the year.

PROPAGATION BY OFFSET

Propagation by offset is only advisable with plants of a branching habit where several offsets are made from one rootstock, such as in the Primula auricula and Primula marginata and their varieties.

In that case each offset is broken off with a heel in July, placed in a small pot of sandy loam and set deep in ashes or fibre in a propagating frame. Some Primulas, the Candelabra and Cortusoides sections particularly, have a unique habit of growing leaves on the lower tier of the flower stem, particularly if they are growing in shade, and in a rich soil. If the flowering top is cut off, the leaves develop, and aerial roots appear from the base of the tuft. The tuft should then be cut and potted up firmly, where it will readily establish itself as a new plant. This is called pelorial growth. Plants formed thus are ready for planting out in May.

30. May 2013 by admin
Categories: Plants, Tuberous Rooted | Tags: , , , , | Comments Off on Growing Primulas

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