Primula Odyssey

When I moved to Michigan on a day much like today (snow in March), I had left behind a California garden full of succulents and tropical plants like fuchsia and hibiscus.  Now it was time to regroup.  I studied the English cottage garden (always an ideal) and prepared to grow herbaceous borders.

Browsing through the seed packets at the garden store, I found Primula veris.  I had read about primroses in English gardens so decided to try it, though it looked difficult.  Two years later, I was enchanted.  The plants grew vigorously, self-seeded, and helped to make spring cheerful and light.  That was the beginning of an odyssey into understanding and growing this genus.

A classic polyanthus. I call this one "Old Yellow".

The most familiar Primula are the polyanthus "primroses".  These are hybrids and many selected varieties exist.  The flowers are held on a stalk, usually above the leaves.  Actually, these are not true primroses.  Botanically minded gardeners sometime refer to them as Primula X polyanthus to indicate that they are hybrids.

Primula vulgaris "True Blue"

The true primroses are Primula vulgaris, a European species that is well known as an English wildflower (but apparently much less common in the wild now).  The flowers are not mounted on a stalk, but arise singly from the crown of the plant, thus are sometimes referred to as "acaulis",  "caul" referring to a stem.  The classic P. vulgaris is a lovely creamy yellow (the color sometimes called "primrose").  But there are many color variants that have either occurred naturally or through hybridizing with garden plants.

But the genus Primula is not limited to our familiar garden plants.  Primulas exist in the wild all over the world, though the single species in South America is likely a modern introduction.  I can make this statement because I possess the most authoritative book on Primula in existence and it describes the range and distribution of the genus. The book is Primula, by John Richards (Timber Press).  Anyone who has become as obsessive as I have about primulas should have the book, which describes the history, distribution, and biology of the genus, as well as its taxonomy.  There are also a selection of color plates.  But for a really wide selection of pictures of primulas, see Pam Eveleigh's gallery of Primula species  (she uses Richards' taxonomic scheme).  As Richards makes clear, the overwhelming majority of primulas are from Asia, or as he puts it, "the eastern Sinohimalaya".

Candelabra primulas

Fortunately, the English, being great plant explorers, brought many Asiatic species home and they are available to gardeners.  The candelabra primroses are descended from those early collections.  They have been hybridized and released as special varieties, which are usually grown in sweeps together. But the species are still grown. The plant blooming to the left is Primula burmanica. Primula helodoxa is just visible to the right.  The hosta behind them is full-size; P. helodoxa is very tall.  The Asiatic primulas appear to require continual seed-harvesting and replanting.  For that reason, there are not many left in my garden.

Primula auricula

Another species that has been widely adapted to gardens is Primula auricula.  There are some varieties that are spectacularly colored, so that they almost appear to be from outer space.  They are usually grown in greenhouses and brought out only for flower shows.  But there are garden auriculas too. Note that the foliage is quite different from the other primulas shown.

Primula juliae

Primula juliae is not only a long-lasting and enjoyable garden subject, but was also the source of some of the colors now available in polyanthus.  It has a different growth habit, creeping to form a little colony over time.

Having grown, loved and lost a number of primulas, I've come down finally to concentrating on those I know will have some staying power in my garden.  They include my faithful Primula veris, the acaulis P. vulgaris types,  P. juliae, and the endless varieties of polyanthus. But probably I'll always be tempted by another challenge to engage more primulas.

This polyanthus is of the true "primrose" color.

Note: this article follows another one on primulas, Primula Fever, which describes more primulas and their hybrids and has more pictures.

Primula Fever

Gardening is not just about food, it is also about beauty.  The true gardener dreams of the moment a particular flower will share its beauty.  This is usually after months or perhaps years of cultivation and fussing.  From the viewpoint of the plant, all that beauty and fragrance is aimed at one thing: pollination. But for the gardener, just those few perfect moments are worth the long months of waiting.

Primula veris, the cowslip

This time of year, my dreams often center on a particular genus, Primula, which are the true primroses.  The name is derived from the fact that they are often a first plant to bloom in the spring, thus "first rose".  The modest and cheerful English wildflower, Primula veris (the cowslip) is one of the most welcome sights in my spring garden.

But there are many species of Primula, and many cultivars and hybrids.  The common garden primroses most often seen in cultivation are mostly "polyanthus", which are descended from hybrids of P. veris, P. vulgaris (the true primrose), and P. elatior (the oxlip).  Another species, P. juliae, has added more color range.

Because I was so enamored of primulas, I chose a garden primrose as my gravatar for this blog.  The picture is not of a "buttercup" but of a yellow polyanthus primrose that has been a sturdy guest of my garden for many years now.  It was given to me by a friend, which is the way primroses often get passed around.

Grace's Red

Two of my other favorite primroses were also given by a friend.  I've named them "Grace's White" and "Grace's Red" in her honor.  These are also sturdy and prolific.  Grace originally obtained them from yet another friend, who found them growing by an abandoned house.  It would be wonderful to know the full history.
 

Grace's White

Now I have divided and distributed these plants several times.  Primroses are best divided during their active growing periods, which are fall and spring.

I have grown many other types of Primula that I have started from seed.  This is a rather laborious process but the surest way to get many of them, since they don't all divide well and seed-starting is the way to get a wide range of types.  I've ordered many different ones from the North American Rock Garden Society seed exchange. I was able to start most of them, but many proved not to be hardy here in Michigan.

Long before I ever grew any Primula, I studied them in biology classes.  They are the classic example of self-sterile flowers.  Most of them have obligate outbreeding, that is, cannot pollinate themselves.  This is done both with genes and because the style and stamens are designed so that it is structurally impossible. Two types of flowers, pin (long style) and thrum (short style) exist; this is called heterostyly. Hand pollination is usually necessary to obtain seeds in the garden.  Here is a guide to hand pollination of primulas.

But a very few species do develop homostyly and can produce seed.  I inadvertently started a colony of candelabra primroses in my garden. I'm not sure of the species or cultivar because I had tried a number of different species in that bed the year before.  It may even be a self-sustaining new hybrid.

A rather perverse charm of Primula is that they are often short-lived if not cultivated very carefully.  They require top-dressing with compost and good fertility, not to mention water and protection from hot sun.  So I've lost many of them, and saved others through a last-ditch effort. Now I'm going to be trying to recover some of my favorites by starting seed as early as December, with long periods of chilling, warming, waiting, and slowly transferring the tiny plantlets until they are ready to plant in the garden.  I won't see any flowers from this year's seed-starting until next year.  But that is the price of having a lovely show of primroses in the early spring.

Note: There is a second post on Primula in the garden, Primula Odyssey.  Other posts on this subject will be labelled "Buttercup" for search purposes.

Buttercup

Yes, I know it's not a buttercup (Family Ranunculaceae). If you don't get the joke, I'm not going to help you.