Plant of the month: March
Name: Lathyrus vernus syn. Orobus vernus
Common name: Spring pea, spring vetchling, spring vetch, spring bitter-vetch, bitter vetch
Family: Papilionaceae
Vital statistics
Height and spread: 20-45cm (8-18in) x 45cm (18in)
Form: Herbaceous perennial
Soil: Fertile, humus-rich, well-drained
Aspect: Full sun or light dappled shade
Hardiness: Fully hardy
Lathyrus vernus @ Rosemoor
These pretty, ground-hugging spring peas can be found to the right of the main track to the Fruit and Vegetable Garden, just after crossing the bridge over the stream. At a time of year when yellow flowers (daffodils, primroses, celandines) and blue flowers (bluebells, Anemone blanda, grape hyancinths) predominate, it is refreshing to come across an unusual plant with distinctively different colouring. Grown at Rosemoor for the first time in 2004, Lathyrus vernus proved to be very popular with our visitors.
Lathyrus
This is a genus of 150 species of annuals and herbaceous or evergreen perennials found growing on sunny banks, grassy slopes, open woodland or wasteland in temperate regions of Europe, Asia, America and East Africa.
Many are climbers with tendrils, while others are clump-forming. The climbers can be grown through shrubs or over a bank, while the clump-forming species are suitable for rock gardens, woodland gardens or herbaceous borders.
Sweet peas, L. odoratus, need support and are suitable for a trellis, arch or a border with some means of support.
Lathyrus are grown for their showy, pea-like flowers, which come in a wide range of colours, many of which are scented.
Lathyrus vernus
This is a clump-forming, herbaceous perennial with upright, angular stems, mid- to dark-green leaves, with two to four pairs of sharp, pointed, pinnate leaflets, up to 8cm (3in) long.
The flowers are produced in short racemes of up to six flowers, 2cm (0.8in) in length, reddish-purple in colour and becoming shaded greenish-blue with age.
The plant may cause mild stomach upset if ingested.
L. vernus ‘Alboroseus’ has pink and white flowers and grows to 35cm (14in) in height.
L. vernus ‘Rosenelfe’ has pale pink flowers and grows to 30cm (12in) tall.
AGM
The RHS Floral A and Joint Rock Garden Committee awarded Lathyrus vernus an Award of Garden Merit and described it as: Compact, clump-forming herbaceous perennial to 45cm tall, with dark green, pinnate leaves and short racemes of up to 6 flowers 2cm long, blue-purple, shaded greenish-blue with age.
Cultivation
Grow in fertile, humus-rich, well-drained soil in full sun or partial shade.
Deadhead regularly then cut stems down to the ground in autumn.
May be attacked by slugs, snails and thrips and may suffer from root rot in wet conditions.
Propagation
Soak seed and sow in containers in a cold frame in early spring.
Divide in early spring, although they sometimes resent disturbance.