It is not entirely frost-hardy, but untrimmed in the milder climates it grows rapidly and to a considerable height and, coming as it does from the edge of the sea on the Californian coast, it is very tolerant of salt-laden winds. Indeed, as a shelter belt-rather than a trimmed hedge-in mild areas it is equal to any of the conifers normally used for the purpose. Thuja plicata, the western red cedar, is another conifer with several forms that can be lightly trimmed as a hedge but which ultimately grows to a considerable height. It is better used as a screen which can be topped at the required height or left to go to its natural height as a screen or windbreak. Cedrus atlantica f. glauca, the blue cedar, Tsuga mertensiana, the hemlock, and Metasequoia glyptostroboides, the dawn redwood, have been trimmed, at Wisley and elsewhere, into attractive hedges. Each has its own special feature and it will be interesting to see how long each can be maintained as a useful hedge. Cedrus atlantica f. glauca has distinctive blue-grey foliage and, carefully pruned, it quickly produces a narrow hedge. Untouched, it grows quite quickly upwards and outwards and, so left, it is entirely unsuited to all but the largest gardens. Tsuga mertensiana has fine foliage similar to that of the yew but it has to be shown how long it will withstand persistent clipping. Metasequoia glyptostroboides, the third of this group, arrived from China in 1948. It grows rapidly in moist soils but tends to form a huge butt or bole in many situations that would make it unsuitable as a hedge. Its leaves change to a pleasant yellow in autumn before falling and it is more likely to become a useful ornamental or possible untrimmed shelter where winter shade is not wanted. Many other conifers can be planted to form useful untrimmed screens but many tend to be too spreading for the average garden. For larger gardens and public parks a few are among the best for the production of shelter belts, being firm of root and resistant to the worst gales. Pinus radiata, the Monterey pine, from the same part of California as Cupressus macrocarpa, grows rapidly to a massive tree that is extremely root firm in all but the thinnest of soils. Several other pines are almost as useful as are several spruces and firs (Picea and Abies, respectively) while the massive monkey puzzle, Araucaria araucana, can stand bold in most windswept situations. Other Options Turning now to broad-leaved or flowering plants the choice for formally trimmed hedges is not very great but, as already suggested, almost anything can be planted in a row to form a lightly pruned or untrimmed screen. The privets, Ligustrum ovalifolium and its golden and silver forms and related species, have been so widely planted as to become common and looked down upon. They are cheap, coming easily from cuttings struck in the open; they are quick growing and can be trimmed to make quite neat hedges, mostly clothed from top to bottom for many years.