Cortaderia selloana Seeds | Pampas Grass
LATIN NAME: Cortaderia selloana
COMMON NAME: Pampas Grass
Plant Profile
Pampas grass is a plant that has been both adored and banned, sometimes in the same country and sometimes within the same decade. The clump is a dense fountain of long, arching, sharply serrated leaves, grey-green and tough, rising to two metres, and from it in late summer come the plumes: dense, silvery-white, feathery panicles on stems up to three metres, held for months and turning to straw in winter. It is dioecious, and this is the detail most gardeners miss — only the female plants produce the full, fluffy plumes, while the male panicles are narrower and scruffier. It comes from the pampas of southern South America, from Argentina and Uruguay through southern Brazil to Chile, where it grows in damp grassland and along ditches, and it was introduced to Europe in the nineteenth century as an ornamental and a source of dried flowers.
Science & Biotechnology
The reproductive biology explains the plant’s success as an invader. A single large female clump can produce a hundred thousand seeds in a season, each with a plume that carries it on the wind for kilometres, and the seed bank remains viable for years. It also spreads vegetatively, and root fragments moved in soil or by machinery will sprout. In California, Hawaii, New Zealand, Australia, Spain and South Africa it has escaped into coastal scrub, grassland and riparian margins, where it forms dense stands that exclude other vegetation and increase fire load. The sharp leaf margins are silica-reinforced, which is why they cut, and why the plant is unpleasant to remove without armour. Research on control has focused on the seed bank and on the timing of cutting, because a single missed season refills it.
Uses & Benefits
As an ornamental it is unmatched for a bold statement in a large border, a gravel garden or a coastal planting, and the plumes are a staple of the cut-flower and dried-flower trade. It is also useful as a windbreak on exposed sites and for stabilising loose ground, which is part of how it escapes. The leaves were used for thatch and for weaving in its native range, and the plumes for decoration. In the garden it needs space, full sun and a site where its self-sowing will not matter; the sterile cultivar Pumila is the responsible choice in a mild climate, since it is smaller, flowers earlier, and sets no seed. Wear gloves and eye protection when cutting it back, since the leaves can cause serious eye injury.
Growing from Seed
Sow in spring on the surface of a free-draining mix, barely covering the seed, at 18 to 22 °C; germination is fast, usually within two weeks, and the seedlings are robust. Grow them on in full sun, in pots that are not too rich, and plant out after the last frost. The plant is tolerant of almost any soil, including heavy clay and salt, but it flowers best in full sun with adequate moisture in summer. Cut the old foliage and stems to about 30 cm in late winter, before the new growth starts, and divide congested clumps in spring. In a mild climate, remove the plumes before they shatter to prevent self-sowing, and check whether the species is regulated where you garden before planting it at all.
Our Take
A spectacular grass with a serious invasive record; grow a sterile cultivar, cut the plumes, and know your local rules before you plant it.
Related Reading
Gardeners who grow Pampas Grass often pair it with these related subjects: