THE ROCK

Auckland Star, Volume LXVII, Issue 181, 1 August 1936, Page 6 (Supplement)

THE ROCK

A rock garden is the most suitable way of dealing with a steep bank and for forming a suitable setting for a liouse oil a hill. It is also a method whereby a large number of different kinds of plants can be grown in a small area, and as they have a long seaeon of flowering, there is usually something out all the year round. Alpine plants are also very interesting. Many have very bright coloured flowers, and out of all proportion to the foliage, which in many cases is very minute, and the way they hug the rocks and fill up the smallest crevice is very interesting. If there is any choice of site take one facing the full suri at mid-day, where there are no overhanging trees and no stronggrowing, coarse shrubs nearby to send their roots in amonji the rocks and rob the small plants of their food and water. If the bank is too even, excavate valleys and throw up the soil, increasing the height and extent of miniature mountain ranges. Try to reproduce something you have seen in Nature, a range of mountains with their valleys and spurs, one single peak, if there ,is only room for one, and an irregular shingle slip if height is unobtainable. Before commencing to build, clear away all couch grass, docks, and other spreading weeds which would grow up among the rock and be a source "of perpetual worry. Outline the main features with the soil and small stones as a foundation, then face up with as large rocks as possible. The choice of rock is the next considerate. If near a <>uarry where thi? rotten rock overlying the blue stone can •be had, it is most suitable. It is comparatively light, and can usually be had in large blocks. If the hard face is turned outwards it docs not weather at all, and being rough the pieces hold well. Weathered limestone is very suitable where it can be had. and the rocks which are dug out of the garden or are strewn about the surface are very suitable, and do not look too new. Brickbats, drain pipes, burned glass and stones with shell on, these should never appear in a rock garden. When these bricks and other rubbish are cemented together forming caves, arches and overhanging cliffs they, form about as unsuitable conditions for the cultivation of alpine plants as it is possible to provide. A firm foundation is most essential, for it should be possible to climb all over the rock garden ,without displacing a stone. Place the stones in such a position that the top side will slope in towards the soil. This causes the rain water to run inwards to the plants, thus /providing, them with water whenever there is a shower. To provide a bold effect eome of the largest stones can be placed in such a position that they are nearly all in view, but as a rule, at least one-third of all th<> other stones should be buried in thi l soil. The stones or rocks hold up the soil on,a steep bank; they shelter the plants from cold winds; they absorb heat during the day and radiate it during the night, thus providing conditions more favourable for the growth of tender plants than the open border does, and enabling many to bloom early, and keep the soil cool and moist during warm, dry weather. Good drainage is essential, and if the soil is heavy it must be mixed with small stones. As building proceeds use ordinary soil mixed with stones for fixing the rocks, but after the structure is complete the soil in the pockets and in the crevices should be removed to a depth of at least a foot and replaced with specially prepared soil, which must be rammed in firmly and all cornefs filled. Suitable soil is composed of two parts clean loam, one part gravel, stone chips, or lime rubble, and one part leaf mould. A little peat will be required for some varieties and lime for others. When planting make the plants very firm. They like to get into a tight corner, and thrive better round the side of the pockets than in the centre. Autumn is the best time for'planting, for they become established before winter, and are ready to flower in spring. If a rock garden is built too late for autumn or winter planting it had better be sown with dwarf spreading annuals and planted at the proper time. Alpine plants, if not properly established, have a bad time during the warm summer weather.