WALL GARDENING

New Zealand Herald, Volume LXXI, Issue 21810, 26 May 1934, Page 8 (Supplement)

WALL GARDENING

PURPOSE AND METHOD There arc many gardens in which some change of level affords an excellent opportunity for building a rough retaining wall. Its purpose is perhaps to buttress the soil of some sloping bank, but in reality its ideal function is to welcome alpine plants among its nooks and crannies. Such a wall is best constructed of stone, and, unlike a masonry wall, the stones may bo of all shapes and sizes. The wall, moreover-, should not be perfectly upright, but incline from the vertical at an angle of at least 10 degrees. The bottom layer of stones needs to bo very firmly embedded and for this a trench should bo taken out the desired length. It must be at least Sin. in depth and have a breadth equal to that of the base of the wall. The bottom of this trench requires to bo rammed firm and level. In very heavy soils it is wise to excavate an additional 6in. and fill this portion with rubble. A few inches of soil should be replaced on top, and made very solid. Such a foundation, with the heaviest stones buried -tin. to Gin. below groundlevel, will be satisfactory for a wall up to five or six feet high.

CREVICES AND FISSURES The planting is best done at the same time the stone is laid. The roots of the plants should be placed carefully between the crevices and allowed to penetrate into the soil of the bank behind the wall. The crevices and fissures should be filled with good garden soil and the whole made perfectly firm, ix/i must be packed between each ?ayer of stones and care taken to see that the joints between the blocks of one layer do not come exactly above the joints of the lower layer. It will be found an advantage to include a few of the larger stones in each layer to' extend upward into the next layer to act as "keys." The ideal position for a dry wall is in full sunshine. There need be no hesitation, however, about building such a wall in the shade, if this is the only position available, although a shady, dry wall will not present such a colourful picture as one in a sunny spot, filled with sun-loving plants. If the garden features a sunken lawn, the banks may easily be transformed into dry walls. A flagstone path in the rock garden, flanked by a low retaining wall, clothed with such plants as arabis, pinks, dwarf campanula and saxifrages, presents quito an old-world appearance and gives added beauty. The idea might be further extended to the low banks which sometimes border the driveway to the residence. It will be found that many alpine plants, especially the woollv-leaved species, which damp off on the level in the rock garden, will weather successfully the wot season on a dry wall. The difficult Erodium clieilanthifolium is an example. The Lewisia species and the androsace family, among which A. lanuginosa and A. sarmentosa are excellent and take well to wall conditions. Planted near the top of the wall Clematis alpina, never grows coai'sely, will trail in delightful fashion, and Tropaeolum polyphyllum is worth ingAmong other suitable sujects may bo listed, Asperula in variety, aubretia, alyssum, arabis (double flowered) iberis in varieties. Lithospermum prostratum heavenly blue, Saponaria ocymoides, Heliefirysum bellidioides and dwarf alpine phlox. While for a wall deeply or continually shaded, a beautiful effect may be obtained by planting no more than a selection or hardy ferns, and Arenaria verna or A. baleariea.

MANURING CITRUS TREES

EFFECTIVE REMEDIES Numerous carofully conducted experiments have readily demonstrated the great benefits to bo obtained by means of a few pounds of fertiliser for each tree. Excessive nitrogen is to be avoided, especially when applied in the form of dried blood or organic manures, which encourage the formation of thick, rough-skinned fruit. On the light soils especially potassic fertilisers exert a great influence on the yields and quality of the fruit. Citrus trees which have borno a heavy crop should always be liberally and promptly manured to assure a reasonable crop the next seasipn. Shy bearing trees and those which flower well but bear badly, will bo found wonderfully improved by tho application of nitrogen as a top-dressing a short time before the trees como into flower. Tho lemon being an evergreen tree and capable of continuous and heavy bearing, the benefits of liberal manuring cannot be over estimated. There are two main seasons when manuring is of most value —February-March, when tho trees are usually laden with a heavy crop of green fruit, and August-Sep-tember, when most of the crop has been removed, and the trees are preparing to push out new growth and again blossom profusely for the next crop. A mixture of fertiliser which has done good service is composed of superphosphate two parts, boned 11st 0110 part, sulphate of potash J part, at the rate of three pounds per tree, largo trees more in proportion. If tho land is lacking in nitrogen, as shown by the sickly yellow colour of the foliage, two parts of nitrogen may be added, but nitrogen is better used in small top-dressings during the season. All citrus trees are susceptible to pests and diseases of various kinds. Weil-manured trees usually do not show the bad influences so much, being more ablo by their better condition to withstand the ravages, but tho best known remedies should be used to keep the trees clean. Immediate results in disease control are not to bo expected. It takes timo for the potash content to be absorbed by the tree in sufficient quantity to enable the tree to be more resistant to disease.