Today many of us think of primroses almost entirely as potted plants where the two Chinese species, Primula obconica, and malacoides, are the most popular. Of course, if one has a greenhouse or a not-too-warm window, one’s interest can logically be centered on these two beautiful primroses.
However, primroses can also be grown in the garden from seed. The yellow-toned primrose of Europe, Primula vulgaris, has long been the favorite of grandmother, great grandmother, and great grandmother.
However, my own favorites are the “many-flowered” or polyanthus primulas, particularly the so-called Colossal Strain, which has beautiful, large flower clusters on tall stems. It is not surprising that one of the parents of the modern polyanthus group is Primula vulgaris, the cowslip or oxlip of the European woodlands.
Primroses Needs Attention
Primroses demand little from the gardener and respond with an abundance of colorful blooms in the spring if a few simple rules are followed. Winter protection in extreme northern, western and mountainous sections of the United States is necessary.
Primroses do best if given eastern exposure, morning sun, and shelter from wind and midday heat. They do not grow well in extreme heat or cold.
Several years ago, we responded to an ad in a flower magazine and sent for some plants. The plants were divided and, when unpacked, were somewhat dried up, but we planted them anyway on the north side of a grape arbor which turned out to be just about right for shade.
Dry as they were when received, they soon grew into friendly tiny plants. When they bloomed, most of the blossoms were of the polyanthus type and yellow, copper, or rust. We didn’t have any “kick” coming, but we had hoped for a more comprehensive color selection.
Next, we ordered seed from an Oregon firm making a specialty of primrose seeds and plants. Explicit directions told just how, when, and where to grow them when the origin came. That was more like it!
Sowing Primula Seeds
In general, primula seeds may be sown at any time of year. The planting time in colder climates is dependent upon facilities for the care of seed receptacles and protection of the seedlings. It takes about a year to produce blooming plants, although, if sown in early summer in more temperate localities and set out in rich soil, some may make blooming plants the following spring.
If you have a cool greenhouse or well-protected cold frame, the time can also be considerably shortened. We have found that the seed of many primulas will do best sown in late winter or early spring.
Expose the flats or pots to alternate freezing and thawing before placing them at a 60 to 70 degrees temperature for germination. In warmer localities or where the frost season is past, the seed should be scarified: On a pane of glass, place a sheet of “oo” sandpaper.
Over this, distribute the seed. Then take the second sheet of sandpaper and gently rotate the seed between the two sheets, scratching the outer coat to allow moisture to enter more readily and hasten germination. Be sure to do this carefully to avoid crushing the seed.
On the other hand, some people feel the best germination results from freshly-harvested seed sown in July, August, or September. Then, the fresh seed usually germinates in from a week to 10 days, provided the seed containers are set in a cool place for germination and are not permitted to dry out.
Preparation For Sowing
You can use flats, pans, or pots for sowing, but they should be sterilized. I’ve to use scalding hot water. Be sure there are plenty of openings in the bottom of the container to ensure good drainage.
Place a layer of about one inch of peat moss in the bottom mixed with a small amount of either raw bone meal or a balanced commercial fertilizer. Then fill the flat to within a one-half inch of the top with a good soil mixture like an African violet mix—level the soil to ensure uniform coverage of the seed.
If you use a flat, mark out the rows. In rows, you can stir the soil between the seedlings and apply fertilizer without getting any on the plants.
Press the seed into the ground with the edge of a popsicle stick. Then barely cover with a thin layer of finely sifted peat moss, over which place a piece of open mesh burlap cut to fit inside the seed fiat.
Wet thoroughly with a fine spray to avoid washing out the seed. Cover the fiat with glass to reduce evaporation and place a sheet of paper over the glass to keep out the light.
Cure Or Hardening Of Seedlings
The seed flat should be kept moist but not soggy. Lift the glass daily and wipe the moisture from the underside. As soon as the seedlings show, remove the burlap, substitute a fragile covering of finely sifted peat moss, and give the seedlings air by tipping up the glass covering.
Do not expose the seedlings to the sun’s direct rays, but place them in a light shade or cover with a lath shade. Water sparingly and give them plenty of air to prevent “damping off.” After they have acquired their fourth leaf and are large enough to handle replant into 2 ½” inch pots.
When they have developed a strong root growth, you can transplant them into a cold frame or in a shady seedbed. We space ours about 6” inches apart from each way in the garden.
Avoid planting the seed too deeply or too thickly. Keeping the seed flat too wet or allowing it to dry out are equally bad and do not expose young seedlings to hot summer winds or cold winds in late winter and early spring.
Early snow blankets the plants; they need no further protection for the winter, mulch with peat moss, straw, or hardwood sawdust in dry climates. We have been using oak sawdust with good results.
In mild, damp climates, evergreen is the best winter covering for they permit air circulation and lessen the danger of rot. In wet temperatures or any weather, do not allow a soggy mat of leaves to smother your plants.
Primroses and Pests
Primroses are unusually vigorous and healthy, and the few garden ills worth mentioning are most likely to affect plants weakened from lack of proper care. The strawberry weevil usually attacks only older plants that have been left in the exact location for two or more years.
Its presence is indicated by yellow leaves and, in extreme cases, by wilted foliage and blooms. We find that much of the beetle damage is eliminated by digging, dividing, and replanting the primrose plants each year.
As a preventive for the beetle from mid-May through summer, we use poison bait which may be obtained at almost any seed store. This also helps solve the slug and snail problem, but we often use a flashlight and go out on a snail-killing expedition after dark rather than wait for the poison.
Red spider mites sometimes attack the undersides of the leaves during hot, dry weather and are readily controlled by washing off the tiny webs with a strong stream of cold water or various new sprays. Also, look at Neem Oil as a natural insecticide.
During abnormally wet weather, black spots may occur on the leaves. These spots do not injure the plants materially but detract from their appearance. Usually, they disappear with the advent of warm, sunny weather. Ordinarily, they can be controlled by any fungicide application or two.
Dividing Primroses
When primroses are in bloom, mark the colors you like best and in late spring, after they have ceased blooming, dig them up and pull them apart.
The divisions are easily separated, and you will find this an easy way to increase the number of your specimen plants. Then plant at once in a rich garden soil to which compost, raw bone meal, or a balanced fertilizer has been added.
Trim off the old broken and discolored leaves, water, and shade until new growth has become established. Most of the divisions will be large enough to bloom the following spring.
by F Hubbard