In their eagerness to bloom, primroses are among the most charming flowers of spring. Yet they have other assets that are equally appealing. A fantastic collection of species and varieties can be enjoyed from early spring through the warm days of early summer.
Best of all, they are denizens of the shade but not in their densest form.
By nature, primroses are cold climate plants, preferring coolness and moist soil to heat and dryness. Once provided with proper growing conditions, they thrive easily, and few hardy plants are more rewarding in their performance.
Primroses grow best when shade is during the hottest part of the day. Buildings or shrubs may cast this, or it may be the dappled shade from fruit and other deciduous trees.
In the matter of soils, primroses are easily satisfied. Ordinary garden soil, generally neutral or slightly acid, pleases them. Many eastern gardeners, however, say that auriculas flower better with some lime in the ground.
In the west, lime makes the colors muddy. For this reason, blue acaulis, blue polyanthus, and blue auriculas should have slightly acid soil to maintain distinct and transparent colors.
The vast primrose family can be loosely divided into three main groups for gardeners.
- The early spring flowering group (Vernales) includes the giant polyanthus and acaulis types, the miniature .julianas, hybrids of the cowslip or English primrose (Primrose Vulgaris), and the dwarf, creeping Primrose Juliar, native to the Caucasus.
- The European alpine group of which the auriculas are the most popular.
- The Asiatics upset all orthodox ideas about what a primrose should look like.
Each of these groups has distinct foliage characteristics, which indicate the situation from which they come and the conditions which make them feel most at home.
The early-flowering group, characterized by plants with moderately-sized, neither thick-nor-thin leaves, speaks of soil rich in leaf mold under trees.
Translated into garden settings, it is not difficult to picture beds of primroses in solid colors, dramatic combinations, or even in a multitudinous assortment of hues, under purple-leaf plums, flowering crabs, and cherries, dogwoods, apples, or other kinds of fruit trees.
A more restrained but regal setting is made by primroses blooming under oaks, alders, or other large, broad-leaved trees. After the display, the trees open their leafy sunshades until Fall, providing the desired shade during the rest of the summer.
The European alpine group (including the auriculas) usually have smaller and very thick, leathery leaves covered by a silver meal (farina) or refined, downy hairs, which protect the plants from the reflected heat of rocks.
They nestle in crevices or stony, alpine pastures. These plants willingly take more sun in the garden than the early flowering group. Their soil must be of good tilth but sharply drained and able to hold moisture.
These alpine forms are used for summer showers every ten days in the Alps.
Sandwiched between rocks in rock walls, in the corner of the rock garden, or on perennial borders having relief from full sun, the auriculas give a wealth of flowers, subtle in tint and fragrance.
Even without bloom, the foliage in neat rosettes, often silver-powdered, makes them worth their room and board!
The Wet And Dry Side
Precisely opposite in appearance and temperament are the Asiatics. How could they be otherwise when most of them know but two seasons in their native homes — one wet and the other dry.
They are covered by snow from about October through April when the dry monsoon blows from the Bering Sea. For the rest of the year, it reverses and blows from the Indian Ocean, wrapping the lower slopes of the Himalayas in rain, mist, and fog.
Nevertheless, the numerous candelabras, the belled types, denticulatas, roseas, and many others settle hick into the shadier portions of the average garden. They like heavy soil and as much water in the summer as you care to give.
Their growth and flowering habits are necessarily as strange as their native conditions. The first killing frosts shear leaves off, and the dormant resting buds, hoping for snow but not unhappy without it, sit in the mud and wait for spring.
When they feel emergence is safe, they surge into action. Leaves quickly become large, lust-foliaged plants, and heavy stalks rise simultaneously. Around the stems of the candelabra type, necklaces of bloom begin to circle the two-to-four-foot distance to the top.
A mop of spicily fragrant bells hangs the belled type with the belled type. No plants have more to offer for unexpected and dramatic effects than these primulas from western China, Tibet, and northern India.
In attempting to supply enough moisture for primroses, gardeners often forget how much moisture shade-giving shrubs and trees absorb from the soil. Statistics credit a large maple on hot days as transpiring four hundred gallons of water.
There are two ways to keep the soil moist: watering or conserving moisture with a mulch. No flower can take nourishment in any but liquid form.
With primroses, which develop their flower buds in summer, a mulch with an organic arid steady-leaching fertilizer gives the desired nourishment and coolness.
The mulch time feeds and cools them in summer and protects them in winter. When the beds are remade, this mulch is dug into the soil as needed.
Primroses can be moved easily without checking their growth throughout the spring and summer into early Fall.
However, allow at least six weeks of growing weather for root development before killing frost.
Always apply new mulch after resetting the divided plants. Dividing the old plants is best done after blooming, every year or every other year, depending on whether the growth has become crowded.
Using Mulches
On the other hand, the mulch is best renewed every year to keep the plants cool during the summer. Barnyard manures make excellent mulches but are not easy to come by in city gardens.
Good, too, is an organic concentrate of emulsified whales, including the bone and baleen. This is obtainable at a meager cost anywhere in the country.
When using, thoroughly mix the two-pound packages with 20 pounds of good quality, dry peat moss. This makes a clean, long-lasting, and odorless mulch that does not spot the leaves.
Red spider is usually discouraged by planting primroses in semi-shade and keeping them moist during the summer.
However, Aramite is effective against this pest. Slugs and cutworms can be the bane of any garden. Metaldehyde-based baits attract slugs and snails, killing them by dehydrating their body fluids—the same materials poison cutworms.
Root weevil has a cosmopolitan taste and enjoys roots of all kinds, including grass. Keep the adult beetle in check by using apple or bran bait containing a stomach poison.
Also, there are various controls on the market for the larvae, or weevil, in the soil should the beetle ignore the bait until after eggs have been laid.
That relative term, “hardiness,” is often a factor in discussing primroses. For example, the winter is successfully in Quebec, where the snow lies deep and long into the spring.
But the rash eagerness of the early spring flowering primroses, coupled with mild winter temperatures, play havoc with them when a sudden, subfreezing drop occurs.
The plants can usually return to semi-dormancy safely if there has been a natural hardening-off process by gradual temperature decline before the mild period.
During the hardening-off process, when evergreens go into a state of partial dormancy, the transpiration of moisture corresponds to the plants’ reduced absorption. In turn, the sugar content is increased, enabling the plants to resist water loss.
Even slow thawing often allows plants to regain sufficient water content to escape injury.
Winter Cover
Therefore, if there is no snow to keep the early spring flowering primroses (Vernales) inactive, overall protection of some non-packing material, such as rock wool, wood excelsior, or evergreen boughs, should be used.
Covering retards evaporation brought on by a sudden, hard freeze and slows up the thawing process. It also keeps the plants dark and semi-dormant since primroses bloom with the lengthening days and increasing light.
Such protection is usually put on soon after the first hard freeze and allowed to remain until early spring. Then it is removed gradually, according to the weather conditions.
44659 by Florence Levy