Primroses, Indoors and Out

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Primroses, Indoors and Out
Author: Margaret Purcell and Mary Henry, Horticulturists
Bachman's, Inc.

We've all heard the saying down the primrose path. Primroses are a part of our lives. They are also some of the most beautiful flowers for home or for the garden. They come from a large family of plants with hundreds of species growing all over the globe. In the world of plants, primroses are both old and new. There are varieties that have been cultivated for over 500 years and new varieties are still discovered every year. Some are well suited to our gardens and a few do very well as seasonal blooming plants for indoors. These plants are as well known by their botanical name, Primula, as they are by their common name, primrose. The genus Primula was aptly named since the word comes from the Latin primus which means first. Primroses are among the first flowers to grace our gardens in early spring, though most are native to climates that tend to be cold and moist. While they vary greatly in flower color and size, they all grow a rosette of leaves at the base of the plant and hold their flowers above the foliage. Their leaves will vary greatly in size, color and texture, but they are all either oblong or obviate (egg shaped with the narrowest part closest to the stem of the leaf).

Primroses for Indoors
Primroses can be used to bring a unique touch of spring indoors in the winter. The key to getting the most out of an indoor primrose plant is to keep it where it receives bright light (but not direct sunlight), stays evenly moist and as cool as possible. In our winter climate, a sunny window that has a sheer curtain is almost always bright and cool. Direct morning sunlight is great, but avoid the afternoon sun. Ideal temperatures for an indoor primrose are mid-60ºs during the day and mid-50ºs at night. If you can't keep your primrose where it is cool, be sure to keep the humidity high. This can be accomplished by placing the plant on a humidity tray and misting the leaves (not the flowers) regularly. Primroses are sturdy plants that seldom have any insect or disease problems, but it is always advisable to be watchful. If the leaves get dusty, rinse them off with room temperature water. Keep in mind that while primroses need to stay consistently moist they cannot tolerate soggy soil.

Like cinerarias, primroses should be considered temporary indoor plants. Enjoy them while they are blooming and beautiful, and discard them when they are done. While they are technically longer-lived plants, getting them to rebloom indoors is a very difficult task. If you would like to try to keep them, continue watering the plant after the blooms have died back. Trim out the old flower stems. When the leaves die down, trim them off and keep the plant in a very cool place (such as a basement). In the spring, plant the primrose out in your garden. It may re-sprout and bloom again that spring and you may be lucky enough to have a perennial variety.

Primula for Outdoors
Primulas are wonderful additions to the early spring garden, often blooming as early as the crocus and daffodils. There are several types of Primulas that are of interest to northern gardeners. With a little research, you can find primulas to fit into a wide variety of garden conditions including rock gardens, bog gardens, woodland gardens and perennial borders. They also offer a wide range of flower colors, plant sizes and heights. They range from only an inch or two tall to the stately candelabra Primulas that hold their flower on 24-inch stems.

Generally, primroses in the garden prefer a cool site with bright light. It is important that the soil be well drained (their roots will be damaged during the winter if the soil is too wet or heavy). When they are given lots of organic matter and kept watered, their bloom season can last for weeks.
Trying to make sense of the hundreds of species and hundreds of varieties is mind-boggling. To make it easier, the species and varieties that are best in the garden can be divided into four types: Auricula, Candelabra, Denticulata and Vernales.

Auricula-type primroses are low growing, compact plants. They bear their blooms in umbels (clusters of blooms held closely together that all emerge from the same place on a single stem). The umbel of blooms is held several inches above the leaves. The auricula species is hardy to Zone 3 and has bright yellow blooms that are very fragrant. Lots of very nice Auricula type hybrids are available for our gardens, including a number that offer great red blooms, some with yellow eyes.

Candelabra-type primroses are larger plants. The leaves may be 4-8 inches long and the foliage may make a mass that is one foot high and wide. Their flowers are amazing clusters of flowers borne in whorls around the stem. The whorls are several tiers high on tall, stately stems up to 24-inches tall.

Denticulata-types are also known as drumstick primroses. They are hardy to Zone 4 and bring an unusual, globular flower form to the early spring garden. The drumstick primrose flower stems emerge early, sometimes even before the leaves develop.

Vernales primroses include those commonly known as cowslips and oxlips as well as the polyanthas. Cowslips, Primula veris, and oxlips, P. elatior, are both meadow plants that have been used in breeding more refined garden plants. This group also contains the compact Juliana hybrids that are at home in a lightly shaded border.

There are lots of other primroses and adventurous gardeners may want to test some of them in their own microclimates to see if they can be grown successfully. One type that might survive in a sheltered area is the English primrose, Primula vulgaris. They are only hardy to Zone 5, so they are not routinely grown here. Another marginally hardy (Zone 5) but tempting type is the Japanese primrose, Primula japonica. Japanese primroses are considered some of the easiest candelabra-type primroses to grow, assuming you have a warm microclimate. In addition to all the true primroses (botanically Primula) there are a few impostors that share the common name. Evening primroses are actually Oenotheras, not Primulas. It is important to be sure the plants you are dealing with are really Primulas, because the others have very different growing requirements.
Beautiful indoor primroses in bloom are available at Bachman's during the winter. Many outdoor primroses can be grown successfully from seed and Bachman's usually has a good selection on the various seed racks. Some types, such as the Juliana hybrids, do not propagate true from seed and should be purchased as plants. Plants are usually available from specialty growers such as Rice Creek Gardens in Blaine, Minnesota. For real enthusiasts, there is the American Primrose Society. It can be contacted by mail at 6730 W. Mercer Way, Mercer Island, WA 98040 or at their web address, http://www.eskimo.com/~mcalpin/aps.html.

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