Events

Flowers from The Cape

Nick Wray (Superintendent of University of Bristol Botanic Garden)

Restios or Cape reeds

Few plants have the variety of stature and form possessed by the restios or cape reeds. An added attraction is that all restios have the quality of movement in the slightest air flow and in stronger winds their stems will rustle, producing a pleasing sound effect uncommon in most other garden plants. Southern Africa is home to 330 species of restio and these are found exclusively in the fynbos, a unique plant community found predominately in South Africa. Strong, evergreen and persistent, their subtle colours of greens and browns add a graceful quality to the garden. They are easily grown in pots and containers and where the climate is mild they can be established outside in sheltered positions.

Cultivation of Restios

Growing conditions

Restios are chiefly mountain plants that appreciate free air movement and good light. They should ideally be grown in a position that receives full light and adequate air movement such as a sunny terrace, rock garden or border. They lend themselves to pot culture and this gives the added advantage that they can be moved into a protected environment during the colder months. In cold areas they appreciate a cool greenhouse or conservatory or a sheltered part of the garden, where they can be insulated against the cold and the damaging effects of wind chill. In milder areas they can be kept outside all year round. They make excellent plants for coastal planting, being both salt and wind tolerant.

Composts

Most prefer an acidic soil or compost, well drained with a high organic matter content. A compost of 40% finely milled composted bark or peat, 20% bark, 30% silver sand and 10% loam such as John Innes No. 2 is a good base mix for most restios. Variations on this mix can be used providing the requirements of moisture retention and excellent drainage are observed. When planting in pots, crock the pot well so that compost does not get sodden at the base of the pot. This is particularly important with many ‘ornamental’ pots which often have a recess in the base that does not drain fully. Pot grown plants are best re-potted in spring when temperatures are beginning to rise. When planting in the garden ensure that the site chosen will not become waterlogged. On heavy soils it will be necessary to create an area of new soil for planting. This can be done in a raised bed or by excavating a large hole and filling it with sufficient new compost to give your restio a large root run to grow into.

Watering & feeding

Plants must be well watered after planting. The addition of a bark chip mulch will help reduce water loss and suppress weeds. Care must be taken on free draining soils that establishing plants are not allowed to become completely dry. New growth appears on many restios in the autumn and will continue to develop through the winter months into the following spring. In cold areas it is normal to keep frost-tender plants on the dry side to prevent rotting during the winter months. With restios this has to be balanced carefully as the plants need water even through the winter months as they are in active growth. During the growing season restios appreciate a liquid feed of 10:20:20 with trace elements. Established plants can have a small amount of slow released fertiliser added at the potting stage or worked in around the surface of the soil in spring.

Pests & diseases

Pests are rarely a problem although mealy bug can become established on plants that spend a large part of the year indoors. Insecticides can be applied to control this pest. Phytophthora is the biggest problem; this soil and water-borne fungal disease attacks plants causing rapid browning of the foliage. Poor drainage and stagnant water help the disease establish. Plants should not be allowed to stand in trays of water and should be re-potted each year to prevent the compost becoming sour. Dead plants should be carefully removed and destroyed including the compost. If the disease threatens, the application of a systemic fungicide will help protect plants.

Propagation

The easiest way to raise new plants is from seed, which is readily available from selected seed merchants. Restio seed is small, 1g of Elegia capensis seed will hold thousands of individual seeds. Pre-soaking the seed with ‘Instant Smoke Plus Seed Primer’ is of the utmost importance. The smoke-impregnated cartridge paper releases its chemicals when soaked in warm water into which the seed is put for 24 hours prior to sowing. For small seeds this can be difficult, in these cases the seed can be sown and the smoke solution watered onto the seed compost. Germination varies depending on the species, but growth should start to appear within three months. Seedlings can be pricked out into the potting mix when they are large enough to handle. Alternatively, plants can be divided when they are large and well-established; this is best done in mid-spring.

Key plants available to British gardeners

Elegia capensis. Perhaps the best known restio in the UK it can grow to 2.2m and its upright stems bear whorls of fresh green foliage. Attractive cinnamon coloured bracts appear on the new stems. The yellow-brown female flowers appear at the shoot tips, male flowers are dark brown. Excellent in pots and worth trying outside in a sheltered corner of gardens in mild districts. Hardy to -3ºC.

Chondropetalum tectorum. Arching, cylindrical, deep almost black-green stems arch over to give an open grass-like effect. Mature plants can reach to 1.2m and produce numerous, small, deep brown flowers in clusters at shoot tips. Excellent in pots and worth trying outside in a sheltered corner in gardens in very mild districts. Hardy to –1ºC.

Rhodocoma capensis. Erect stems to 1.3m arch at the tips and bear numerous sea-green side branches which give each stem a feathery appearance. Flowers numerous, small, chestnut brown and appear in summer. Excellent in pots and worth trying outside in a sheltered corner in all but the coldest districts. Hardy to -3ºC.

Ischyrolepis subverticellata. Erect stems to 1.5m, with cinnamon coloured bracts, bear whorls of green branches. Flowers numerous, small, chestnut brown at shoot tips in summer. Excellent in pots with wonderful plumes of feathery foliage, which give mature plants a cloud-like effect. Excellent in pots and worth trying outside in a sheltered corner in all but the coldest districts. Hardy to -3ºC.

Restio quadratus. Arching, square sectioned stems to 2m with numerous side branches producing a spreading plant with luscious soft-green feathery foliage. Flowers small, brown at shoot tips. A graceful plant with intensely interesting foliage and habit. Easily grown in a pot or established outside in a sheltered spot in mild gardens. Hardy to -4ºC.

Thamnochortus insignis. Erect narrow-stemmed perennial with deep black-green stems producing a vase effect to 1.4m. Flowers small, cinnamon coloured, at shoot tips in summer. Excellent in pots or can be easily established outside in mild districts. Hardy to -3ºC.