Primula Juliae

by Mary Kordes

The Caucasus Mountains, in southwest Russia, were one of the last mountain ranges offering unexplored territory. Julia Mlokossjewicz was raised in this area and accompanied her Polish-born father many times as he explored this rich mountain range for botanical specimens. She continued to be an avid naturalist into adulthood and, on 20 April 1900, while exploring these slopes of her homeland, she discovered a tiny primula growing with moist mosses along a mountain stream.

This charming little species was named Primula juliae in honor of its discoverer. Though some feel it may have reached England earlier, it wasn’t until 1911 that seed from this new species was sent to Oxford. The following year P. juliae, pronounced “jul-ee-ee”, was introduced to the world when a plant was exhibited at the Royal Horticultural Society show and received an Award of Merit.

Primula juliae is the smallest species in section Primula of the subgenus Primula, a veritable jewel of the primula family. The unusual morphology of its root system, the fact that it is stoloniferous, sets it apart from all other species in its section. Its short stolon is a somewhat thickened root that travels laterally just under the surface of the soil, branching to allow the plant to spread and form mats. This petite species has been used to cover large areas, not only for its beauty, but also because of its ability to hold soil in place.

The leaves of Primula juliae form loose rosettes, growing from nodes along the stolon where new feeder roots develop. The nearly rounded leaf blades are small, less than 1½ inches in diameter with a cordate, heart shaped, base. They’re dark green and being glaborous, lacking hairs or meal, are glossy. The leaf stems, correctly referred to as petioles, are up to 3 inches tall, slightly winged, and pink or streaked with red. Growing a new leaf rosette on a stolon induces the plant to grow two new stolon branches from the existing tip, allowing the plant to spread. In it’s winter dormancy, Primula juliae dies back to pink resting buds that are visible on the soil surface. New leaves will grow from each bud in spring.

Primula juliae’s bloom habit is also unique as its flowers grow from the fork where the new stolon sections developed rather than growing, in the usual manner, at the center of a leaf rosette. Several blossoms emerge at each juncture, producing sheets of cheerful blossoms to cover the mat in early spring.

The flower of this plant, the corolla, is brilliant purple-pink with a tiny yellow eye. The corolla is one inch in diameter and consists of five brightly-colored lobes, the petals, with a deep cleft at the tip of each lobe. The tube of P. juliae’s blossom is so long and slender it hardly looks capable of supporting the corolla, but still contains the stamens, and the stigma, style and ovary for reproduction. The tube flares at the top where it meets the lobes but is long and cylindrical, finally nestling into a pinkish ribbed calyx. The flower stem, or pedicel, which is reddish-streaked, holds the blossoms above the leaves. There is an alba, or white, form of P. juliae but it is seldom offered.

It was discovered that the pollen of Primula juliae was compatible with that of other species in its section and, immediately after it’s introduction, it became the darling of plant breeders in the United Kingdom and Europe. Crosses were made in both directions with P. vulgaris, P. elatior, and P. veris, producing lovely hardy hybrids. These hybrids were formerly known as Primula juliana, but are now correctly named Primula x Pruhoniciana.

Many x Pruhoniciana cultivars have been raised from P. juliae crosses, but P. ‘Crispii’ was the first named plant to be shown and introduced to gardeners. The result of a cross between P. juliae and P. vulgaris, it received an Award of Merit in 1916 from the Royal Horticultural Society in England. There are at least two forms of P. ‘Crispii’ in cultivation now, each a different shade of pink.

P. ‘Wanda’, the best known of all Primula juliae hybrids, was introduced in 1919 when it also earned an Award of Merit. This lovely free-flowering cultivar is a rich reddish-purple, achieved through crossing P. juliae with a red P. vulgaris. ‘Wanda hybrids’ are now circulating, so shop with that in mind, remembering that named plants can only pass their name on to their progeny through division, never through the seeds of that hybrid.

Primula juliae contributed its bright color to numerous offspring but, through years of crossbreeding, the x Pruhoniciana now display nearly every color found in the primula family. The most desirable hybrids retain the small stoloniferous habit of their juliae parent, but even the rosette forms are beautiful in their smaller size. The rosette forms grow flower stems from within their rooted leaf rosette, rather than separated from the leaves along a stoloniferous root system.

There are many x pruhonica hybrids, including the vulgaris form with a single flower to a stem, stalked forms with the “polyanthus-look”, Jack-in-the-greens with a ruff of tiny leaves below the blossom, and Hose-in-hose forms displaying one corolla within another.  They offer so much diversity, and are all beautiful.

Double-flowered juliae hybrids have appeared in some breeding programs. I have a tiny semi-double charmer that was hybridized by Dr. Ralph “Herb” Benedict many years ago. It has inherited the small stature of its P. juliae parent, being only four inches tall when in bloom. It has dark green foliage and a rose-pink corolla with small white dots at the cleft of each petal. A small amount of yellow is visible at the base of the petals. I have named this lovely plant ‘Herb’s Gift’.

Experts suggest a moist soil rich in humus as the best growing medium for Primula juliae and its offspring. Here, now, is where paying attention to a plant’s natural habitat is important. Remember the moist, mossy area in which this plant was first discovered? It was amongst rocks along a mountain stream. Drainage would have been excellent, running off the edges of those rocks. This plant needs moisture but cannot tolerate overly wet soil.

I’ve found growing my P. juliae and her children in a rock garden situation, with plenty of rocks, has been quite satisfactory. The rocks insure drainage while still holding enough moisture and keeping the soil cool. I enrich our poor soil with a little compost or aged manure, but must warn that too much nitrogen will encourage the plant to form excess leaves at the expense of flowers. Partial shade, with a bit of morning or filtered sunlight, is a must. Deep shade would result in more foliage but fewer blossoms, and full sun would burn and destroy the plant. Lightly mulching with leaf mold helps to keep the roots cooler and encourages good growth throughout the heat of summer.

Any of the Primula juliae clan, species or hybrids, can easily be propagated from seed or division. Harvest seed when the seed capsules are tan, but not opened, to avoid the risk of seed spillage. Division is best accomplished immediately after bloom by separating the stolons or, in the case of those growing as rosettes, separating the crowns. They can be divided often to start more plants, or replanted into loose colonies to form larger mats.

A feeding program for Primula juliae calls for a half-strength application of a fertilizer low in nitrogen, but containing more phosphorus and potash, very early in spring. Some growers use a product designated as “tomato fertilizer” for this application, as it has the proper component ratios to encourage blossoms and root growth. Fertilize again after the bloom period, this time with a balanced fertilizer to carry the plant through the summer months. Water as necessary to keep the soil moist but not soggy. Conscientious growers feed again in fall, this time with a half-strength application of a fertilizer with no nitrogen (0-10-10), to assure a healthy dormancy.
If you grow your primulas in pots, Viv Pugh, an excellent grower in England, suggests using a gritty, very lean, planting medium, but only for the species Primula juliae. She finds the plants produce more blossoms when the soil mix isn’t rich, but cautions she does not grow the hybrids of P. juliae in pots.

As with so many plant genera, primulas reached the United Kingdom and Europe before finding their way to North America. Collectively, however, hybridizers have named approximately 100 Primula juliae hybrids, far too many to list here, but many of them originating in the United States. Though some have disappeared through the years, hybridizers continue to introduce more of these hardy, colorful plants. Search for them, as I am doing, as they make lovely additions to any garden. And try hybridizing them yourself, for you may produce an even more beautiful Primula x pruhonica!

Bibliography:
American Primrose Society – Pictorial Dictionary of the Cultivated Species of the Genus Primula, 1948
Halda, Josef J. – The Genus Primula in Cultivation and The Wild, 1992
Richards, John – Primula, 1993
Robinson, Mary A. – Primulas, the Complete Guide, 1990
Smith, G. F., B Burrow, & D.B. Lowe – Primulas of Europe & America, 1984
Ward, Peter – Primroses & Polyanthus, a Guide to the Species and Hybrids, 1997

Photo Credit: Primula Julieae hybid "JJ" grown and in the garden of Cheri Fluck