This section is from the book "The Gardener's Monthly And Horticulturist V20", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
(Before the Germantown Horticultural Society).
Since the introduction of the Chinese Primrose, nearly sixty years ago, it has been vastly improved through the patience and perseverance of the florist, gardener and amateur. When it was first introduced, its flowers were not larger than a five cent piece, and generally of a poor shade of lilac in color, but now we have flowers larger than a trade dollar, with the edges elegantly fringed, and in color varying from pure white to the most brilliant crimson. No matter whether it is seen in the conservatories of the wealthy or the windows of the poor, it is always a source of pleasure, being in the Winter what the Geranium is in Summer-time - everybody's plant.
It is as a window plant that I wish particularly to direct attention. I knew of a plant that was in the same window three years, Winter and Summer, without re-potting, and it never was without flowers and always wore a healthy green appearance; the only attention it received, besides watering when necessary, was an occasional top-dressing with well decomposed cow manure, reduced to a powder. I mention this to show its adaptability for the purpose for which it is recommended, not as a practice to be followed altogether especially in this climate, where window gardening in Summer is unpopular, because impracticable, and also to show that it succeeds well under ordinary treatment.
There is no plant so grateful for a little extra attention as the Chinese Primrose. Being a plant with fine roots it must have a light soil. I find a good mixture for them to grow in is half leaf mould, or soil from the woods, and the other half rich sandy loam. I do not wish to confuse by going into details, but will simply say let the soil be light, rich and porous.
It is hardly worth while for those indulging in window gardening to trouble themselves with the details of raising plants from seed, for good seed is expensive, and, being delicate, often fails to germinate in the hands of the inexperienced; but to whoever has a greenhouse or a hot-bed, the raising of their own plants from seed will be found both interesting and instructive.
For the benefit of those wishing to experiment in this line, I will briefly say, take light soil similar to that which is recommended for the plants to grow in, and fill a six-inch pot to within an inch of the top, or what is perhaps better, a box three or four inches deep and a foot or so square, as a box retains moisture longer than a pot; and this is one of the secrets of raising young plants from seed, for they are apt to perish if subjected to too frequent watering until the little plants have gained some strength. After the soil is pressed down to an even surface give it a thorough watering with a fine sprinkler, then allow it to drain half an hour or so, when it will be ready for the seed, which should be thinly and evenly sown, taking care to keep it more in the center than at the sides of the box, then press the seed gently into the soil; some cultivators do not cover the seed at all, but I find a slight sprinkling a benefit, as the little roots take to the soil better. If the seed is sown in the Spring, a shelf near the glass at the warmest end of the house is the best place for the box, which should be shaded from the sun by means of a piece of paper occasionally sprinkled with water; and when the sowing of the seed is deferred until the Summer months a piece of board laid on the box will check evaporation, and, as darkness favors root action, it will facilitate germination, and a cool place, say a frame facing the north will be found the best place during the hot weather; as soon as the seed shows signs of germination a little air and light should be admitted by degrees so as to strengthen the plants by favoring leaf development.
If the seed has been sown as directed, that is thinly, and the surface of the soil has been stirred occasionally with a sharp-pointed stick, the plants may remain in the seed box until they are large enough to be transferred to two and a half inch pots, or three or four plants in a three-inch pot; after potting, care must be taken that the little plants are not allowed to wilt as they are very sensitive in this respect. A piece of paper placed over them will be all that is necessary to protect them until they have started young roots; indeed at all stages of growth the Primula must be carefully guarded from strong sunshine. During the hot summer months a cold frame is the best place for them, especially if it be within the shade of a building or a tall spreading tree - not beneath its branches, for the drip might do serious injury to the delicate roots of this plant. During rain they should be covered by sash, but at no other time, giving them the full benefit of the light and air.
If a position for the frame cannot be had as recommended, they may be shaded by screens made of plastering lath, nailed about an inch apart on a frame the size of the sash; this will admit air and light sufficient during the hottest part of the day. At all times when the sun is not shinning directly on them they must be left entirely uncovered, excepting as before mentioned, when it rains.
At one time it was recommended that the seed of the Chinese Primrose should be sown in this climate in August or September, but we find now that if the sowing of the seed is deferred until so late we cannot get the plants in flower until sometime after Christmas. If there is any time of the year when flowers are more welcome than at another, it is at the gay and festive Christmas time when nature slumbers and humanity is on the alert to secure anything and everything to make home cheerful.
This plant is something more than a cut flower, and not being overlarge it may be advantageously used in all decorations where flowers and plants have a place, as it is infinitely more effective under artificial light than it is in the day-time.
To get Primulas in flower by October the seed should be sown in February. Let the strongest plants be selected and encouraged, but by all means avoid over-potting. I saw, a short time ago, a fine strain of several hundred plants completely ruined through over-potting and injudicious watering. In large establishments it is of course necessary to make several sowings of seeds at intervals of a month or six weeks apart until August, but for a small greenhouse and cultivation generally, one sowing will be sufficient. The plants may be brought on in batches by encouraging the strongest plants, as before stated, and retarding the smaller ones.
This Primula is not at all a free seeding plant, the best way I have found to deal with them is to prepare a box of soil as before recommended and set the plants, the seed of which we wish to secure on the box; the seed as it falls, if the soil is kept at the right degree of moisture, will most of it grow, and the plants may be treated in the way as before advised.
In conclusion let me say, to be successful with the Chinese Primrose, avoid extremes of all kinds, give water when necessary - not every day or every other day, but twice a day if the plant is dry, and not for a week if it is moist.