Plant of the Month: April

Primula vulgaris subsp. sibthorpii @ Rosemoor

Primula vulgaris subsp. sibthorpii is a lesser know relative of the much-loved common primrose (Primula vulgaris). This delightful plant, with its delicate lilac flowers, grows throughout the garden. It was originally introduced by Lady Anne Berry (nee Palmer) when she lived at Rosemoor and we have now planted more groups at the other end of the estate, in the Winter Garden.

Primula

There are about 400 species within this genus. They are mainly herbaceous perennials, but some are woody based and evergreen. They grow in a wide range of habitats, from bogs and marshland to alpine areas. Almost half originate from the Himalayas, and the majority are distributed throughout the northern hemisphere. 

The name primula is derived from the Latin primus, meaning first.  Primrose is from prima rosa means first rose.

The genus is complex, with many different botanical sections. In gardens, they are grouped into three main sections: auricula primulas, candelabra primulas and primrose-polyanthus primulas. P. vulgaris belongs to the last of these groups. 

Auricula primulas are named after the Latin auricula, an ear - the leaves are shaped like ears.  Candelabra primulas are so called because their flowers are borne in tiered clusters, which rise above the basal rosette of leaves.

Primula vulgaris subsp. sibthorpii

Primula vulgaris is the familiar rosette-forming, evergreen or semi-evergreen perennial common primrose.  From early to late spring it produces clusters of salverform, often fragrant, yellow flowers. The many cultivars include ones with double flowers, and almost the full spectrum of colours.

P. vulgaris makes a good carpet in open woodland and on woodland edges. The plants are best spaced about 35cm (14in) apart each way. The blooms have a characteristic fragrance of a mossy bank or deciduous woodland.

P. vulgaris has some culinary uses. Young leaves can be added to soups. And the flowers make an attractive garnish to salads, and can also be used as a cooked vegetable. If picked when first opened, the flowers can be fermented with water and sugar to make a very pleasant and intoxicating wine. Both the flowers and the leaves can be made into a syrup or tea.

Primula vulgaris subsp. sibthorpii has wedge-shaped leaves, with rose-pink, red, lilac, purple or white flowers. It hails from the east Balkan peninsula. It has been known for about 300 years and is the parent of many of the coloured primroses.  It is important in the development of modern primroses as it introduced flower colours other than yellow.

In cultivation it is an easy, vigorous plant suitable for the woodland garden but rarely seeds about in the way the type species does.

AGM

The RHS Rock Garden Plant Trials Subcommittee awarded Primula vulgaris subsp. sibthorpii an Award of Garden Merit and described it as: Semi-evergreen perennial to 15cm, with a rosette of obovate leaves and clusters of long-stalked rose-pink or lilac-purple flowers 2-3cm wide.

Cultivation

Preferred growing locations vary greatly throughout the genus.  Primula vulgaris prefers to grow in deep, humus-rich, moist, neutral to acid loam soil or peaty soil in partial shade.  It tolerates full sun if the soil is kept moist at all times.

Primulas are prone to aphids, red spider mites, leafhoppers, vine weevil, slugs, viruses, primula brown core and grey mould (Botrytis).

Propagation

Surface-sow seed of half-hardy and frost-tender species in early spring, and hardy species in a cold frame as soon as they are ripe, in late winter or in early spring.

Divide clumps between autumn and early spring. This is best done every other year.

Root basal cuttings or offsets in autumn or early spring.

Take root cuttings from dormant plants in winter.