RHS Garden Harlow Carr

Plant of the Month: March

Primula denticulata @ Harlow Carr

From the entrance come down the path to below the restaurant balcony. Turn right and continue following the path along most of the length of the gardens. You will reach the herb garden on your right. Turn left down a slope following a huge bed currently under construction on your right. Keep following the paths down. You will see our tea house on your right. Facing away from the tea house directly in front of you is our lime stone rock garden. The primulas are in the rock garden.

(These directions will change during 2006 as the new entrance comes into use and the "bed under construction" is finished later in the summer).

Primula

There are around 400 species of Primula worldwide, and many hybrids have been raised, grown for their wonderful, sometimes scented flowers.  They are mainly perennial, alpine herbaceous plants with short rhizomes and leaves in basal rosettes, found mostly in northern temperate zones with over half the species originating in the Himalayas.

Primulas are found in a range of habitats ranging from the damp grassy banks and riversides liked by the English primrose Primula vulgaris, to the wet, stony scree of high mountains.

Primula is a complex genus divided into many different botanical sections though only three major groupings are recognised in gardens: auricula primulas; candelabra primulas; and primrose-polyanthus primulas.

Auricula primulas, much loved by the Victorians, were developed from hybrids of P. auricula and P. hirsuta. They are evergreen primulas which bear umbels of several large, flat-faced flowers of varying colours, often with the colour of the flower centres in sharp contrast to that of the petals.

Candelabra primulas take their name from the fact that the flowers on the plants in this group are not arranged in the usual umbel but in whorls set at intervals up an otherwise bare stem. The general effect is thus like a candelabrum.

Primrose-polyanthus primulas are a very diverse group of winter or spring flowering primulas with colourful flowers either borne singularly, clustered in a basal rosette, or on long, stalked umbels. This group contains the English primrose, Primula vulgaris, which can be found blooming in early spring along hedgerows and stream sides throughout Great Britain.

Primula denticulata

This is a robust, deciduous perennial from moist alpine regions of Afghanistan to south east Tibet, Burma and China.

Its leaves are oblong and spoon-shaped, mid-green, up to 25cm (10in) long, finely toothed and mealy beneath.

Stout stems bear spheres of closely packed, yellow-eyed, pale purple or purple, bell-shaped flowers, each 2cm (0.75in) across.

P. denticulata var. alba has white flowers
P. denticulata red has red-purple flowers.

AGM

The RHS Rock Garden Plant Trials Subcommittee awarded Primula denticulata an Award of Garden Merit and described it as: Herbaceous perennial to 30cm, with obovate leaves mealy beneath. Flowers to 18mm wide, pale or deep purple with a yellow eye, borne in dense rounded heads on the erect stems.

Cultivation

Grow in deep moist or moist but well-drained neutral to acid, humus-rich soil in full sun or partial shade.

Cut back after flowering.

May be attacked by aphids, vine weevil, slugs, leaf and bud eelworms and glasshouse red spider mite.

Propagation

Propagate by division in early spring or propagate by seed sown from autumn to spring.