Organic Gardening Tips and Methods Ornamental Trees (Section Four) Palms and Exotic Looks In the past, in frost-prone regions, many pretty Tropical and Sub-Tropical plants were grown for their ornamental effect in the protected environment of heated glasshouses/greenhouses, as the costs of maintenance, particularly heating soared during the twentieth century, the cultivation of these “Exotics” declined. Recently, however, a new style of gardening has emerged that recreates the visual impact of tropical and sub-tropical plants in sheltered, outdoor gardens in temperate regions, this style makes use of hardy, half-hardy, and some tender plants with striking shapes, distinctive textures and attractive, large foliage and vivid flowers. In frost-prone climates, most of the plants used should be hardy enough to survive ear-round. Planting schemes can then be varied during frost-free months by intergrating half-hardy or tender, container-grown “Exotics” into the design, these can be used as focal points or placed strategically within the overall framework of the planting to create seasonal interest, such displays require careful planning of course, as well as the use of a frost-free greenhouse or conservatory in which the plants can be over-wintered. Some half-hardy plants may be planted permanently outside in milder areas, although they will need to be swathed in straw hessian, or other coverings in severe weather to protect them from cold winds and frosts that would otherwise desiccate evergreen foliage, equally important is to ensure that such plants are grown in free-draining soil, to avoid root decay, particularly during very cold, frosty spells. Exotic planting schemes of this type are most likely to succeed in coastal or sheltered city gardens in temperate regions, but variations on this theme may be well worth trying in colder areas. Key Framework Plants Exotic-style plants seldom grow as large in temperate climes as in their native regions, although they can still reach a “fair-sized” vigorous garden plant for outdoor cultivation in the appropriate situation, plants to use as tree-like, structural elements in the exotic style of gardening can be divided roughly into three groups; Palms and Palm-like plants..... Tree ferns..... And Bananas, each contains hardy and half-hardy plants with imposing, attractive foliage, and sometimes flowers, these tropical-looking plants can also be blended with more familiar large, hardy foliage plants, such as elegant bamboos and gunnera. Palms and Palm-Like Plants Several species of palm are grown successfully outdoors in temperate areas, the most familiar being the Chusan or Chinese Windmill Plant (Trachycarpus fortunei) from the Himalayas, this withstands temperatures of -15 degrees C (5 decrees F) or below, if growing a reasonably sheltered position. The closely related T, wagnerianus has stiffer, more wind-tolerant leaves; another suitable palm for a garden setting is the Mediterranean Dwarf fan-palm (Chamaerops humilis). Although it originates in hot, dry regions, it will tolerate temperatures of -10 degrees C (14degrees F) or below when grown in a sheltered spot. Forms with silvery-blue leaves (C, humilis var, argentea) are particularly attractive, Blue hesper palm (Brahea armata) from Mexico and California is occasionally grown in very sheltered sites outdoors in cold areas, it is also an excellent plant for summer garden displays. The Jelly palm (Betuia capitata), although Brazilian and Uruguayan in origin is also surprisingly tough and of similar stature and hardiness to Brahea, known to survive outdoors and develop to about 5m (15ft) in mid-temperate areas, the Chilean Wine palm (Jubaea chilensis), with its delicate feathery foliage is another fine candidate for the exotic-style, as is the Canary Island Date palm (Phoenix canariensis), its delightful dwarf relative; P, roebelenii, is better grown in a container in the conservatory and moved outside in summer. Unless large specimens are obtained from specialist nurseries, borderline hardy-palms should be grown initially in containers until established, they can then be planted out in well drained soil that is reasonably moisture retentive, as the palm stems thicken with age, the plants become more tolerant of lower temperatures, although some winter protection is advisable for some years. Palm like plants, such as Cabbage palm (Cordyline) and Yucca are also valuable constituents of an exotic garden, the New Zealand cabbage or Torbay palm (C, australis) can be grown outdoors in mild temperatures/temperate areas where it reaches 6-12m (20-40ft) in height, Green-leaved C, australis grows without protection in sheltered gardens, but in severe winters may lose some of its foliage, although it often recovers in spring, variants with coloured leaves are not always tolerant if the temperature drops below freezing for some days, species of Yucca, such as Adams needle (Y, filamentosa) and Spanish dagger (Y, gloriosa), also provide an exotic-feel in a garden and can be used as permanent residents within the planting scheme, as both will withstand temperatures down to as low as -15 degrees C (5 degrees F). Tree Ferns Several species of Dicksonia and Cyathea are becoming increasingly popular for conservatories and in sheltered gardens, the Wolly tree-fern (Dicksonia antartica) for example grows well in humid shade, a habit that mimics its native temperate rainforests in Australia, if not already containerized, tree-ferns should be planted with the sawn-off trunk atleast 30cm (1ft) into the ground in a shaded-humid, wind-sheltered site. It is very important, particularly in the first year, to keep the plants moist, they must not be allowed to dry-out, a trickle or drip-feed system to maintain a high level of humidity around the plants will stimulate the natural conditions in which they grow, sometimes, it is better to establish tree-ferns in containers placed in a shaded site, as the developing fronds may burn in bright sun, although D, antartica will withstand temperatures as -5 degrees C (23 degrees F), its crown and trunk should be insulated where more severe frosts can be expected, slightly more tender are the New Zealand species; D, fibrosa and D, squarrosa, both are best grown as container plants which can be given a “summer-outing”, another tree-fern that requires similar cultivation and sheltered conditions is the spectacular; Sago fern (Cyathea medullaris). Bananas The two main genera of bananas grown as ornamentals are; Musa (including Musella) and Ensete, an impressive giant African genus with enormous architectural foliage, both should be grown in moist fertile soil and mulched with well rotted manure, bananas need sun and a sheltered site to prevent their large, paddle-like leaves from tearing in the wind as well as plenty of water and frequent applications of fertilizer during the growing season. A few Musa species, including; M, basjoo, are reasonably frost-hardy and will withstand temperatures down to -8 degrees C (18 degrees F), however, even in sheltered gardens; it is always advisable to provide some winter protection. Young plants should have a deep straw filled pot, (a chimney pot is ideal), fitted over the crown after the foliage has been cut off, a tile across the pot top will prevent rain from rotting the straw, older plants can be protected with a 15cm (6in) mulch of straw placed around each trunk, the foliage will die off in the winter and new shoots should appear in mid-spring. Given suitable “over-wintering” conditions; Musa Ensete and many other banana genera are among the best of all foliage plants for inclusion in exotic planting schemes. A Range of Exotics • Hedychium, • Melianthus major, • Brugmansia suaveolens, • Tibouchiana urvilleana, • Ricinus communis “Zanzibarensis”, • Passiflora caerulea, • Canna “Rosemond coles”, • Hibiscus schizopetalus, • Agave Americana, • Euphorbia mellifera, Other Plants with a Tropical Look • Acanthus mollis, • Aralia elata, • A, elata “Varigata”, • Arundo donax, * • Astelia chathamica, • Beschorneria yuccoides, • Blechnum chilensis, • Cycas, * • Dahlia coccinea, * • D, imperialis, * • Echium candicans, * • E, pininana, * • Eryngium agavifolium, • Fatsia japonica, • Gunnera tinctoria, • Impatiens tinctoria, • Phormium, • Phyllostachys, • Rheum palmatum (and “cvs”), • Solenostemon, * Specimens/Species marked with * represents those that need winter protection in frost prone areas, or use as a summer bedding as/ where appropriate. All information given is within the guidelines of the Royal Horticultural Society (RHS).
Posted on: Wed, 13 Aug 2014 09:54:03 +0000
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