Asperula (Galium)
A family of vigorous, neat, low growing annuals and herbaceous perennials, with whorls of narrow leaves, topped with clusters of small, white, blue or yellow flowers in summer.
Family: Rubiaceae
Botanical Name: Asperula (Galium)
Common Names: Woodruff, hay plant, kiss-me-quick, rockweed, sweet grass.
Foliage: Whorls of narrow deciduous leaves
Flowers: Clusters of small tubular flowers, often sweetly scented.
Flowering Period: Summer.
Soil: Moist but well-drained, fertile soil (chalk, clay, sand or loam). Acid, alkaline or neutral pH.
Conditions: Sun or partial shade. Plant in a north, east or west facing aspect, in a sheltered position.
Habit: Spreading, low growing, mat forming.
Type: Rhizomatous perennial.
Origin: Europe, North Africa and Asia Minor.
Hardiness: Most varieties are fully hardy in the UK.
Planting and Growing Woodruff
Thrives in any moist but well-drained soil in sun or partial shade.
A. odorata prefers a moist, well-drained, humus rich soil, in a cool shady site. Other species require an open sunny site. Annual and alpine species require a very well-drained soil.
Perennial forms can be invasive but digging out unwanted growth easily controls them.
Taking Care of Woodruff
Support annuals with twiggy branches when 4in (10cm) tall.
Pruning Asperula
Pull up and discard annuals after flowering.
Pests and Diseases
Generally trouble free.
Propagating Woodruff
Sow annuals outdoors in April where they are to flower. Gradually thin seedlings to 4-6in (10-15cm) apart.
Divide established clumps of perennial species when dormant, from October to March.
Take short basal cuttings of alpine species in summer and root in a cold frame.
Popular Varieties of Woodruff
Asperula odorata/Galium odoratum (sweet woodruff) is a small perennial with whorls of lance-shaped, green leaves. Slender stems topped with clusters of small, tubular, white flowers appear in summer. Height: 6-9in (15-22cm), spread: 1 to 2ft (30-60cm).
Asperula orientalis (Blue Woodruff) is an attractive hardy annual with rings of green, pointed leaves and pale blue, sweet-scented tubular flower clusters in summer. Height and spread to (30cm). For sale at Suttons.
Asperula suberosa is a low growing perennial alpine form providing a dense carpet of tiny greyish leaves, covered with long tubular pink flowers in June-July. Height: 2-3in (5-7cm), spread: 4-6in (10-15cm).