Pergola floors should be built with a view to permanency. The foundation should consist of eight or twelve inches of clean cinders wet and thoroughly compacted, or of equal depth of crushed stone on which should be laid a Concrete slab four inches thick, composed of one part Portland cement to two of sharp sand and five of crushed one and one-half inch stone, thoroughly tamped. On this place a cushion of one-inch bar sand. Such a foundation should be provided for brick, slate, cement or stone paving. If concrete is not used in the foundations the cinders are best with the sand cushion placed directly on top of them. All paving should have a slight fall; an eighth or a quarter of an inch to the foot is sufficient. This will prevent surface water from collecting.
If brick, stone or slate is used for paving the joints should be pointed with a cement mortar to prevent grass and weeds growing in the interstices. It is seldom practical to successfully grow turf under pergolas, as the shade from the overhanging vines becomes too dense. On open terraces such a treatment is satisfactory and picturesque.
The cement finished floor is the least desirable of all. It has a harsh, mechanical finish which does not fit in with soft, responsive surroundings of the garden. If cement is used much of the glare may be reduced and the texture improved by tinting it. Lamp black and the red mortar stains are used for the purpose. They should be applied in the finish coat, and that rather sparingly, or the efficiency of the cement will be much impaired. Cement paving should have expansion joints cut at intervals to prevent cracking. A cement surface will have a better appearance if it is cut up into small rectangular blocks, either square or oblong in form.
The color of the timber superstructure will be largely influenced by that of the house; when adjacent to the house the color adopted should conform to the residence.
White may always be used with safety and will intensify the shades of green leafage by contrast. There are various shades of brown obtainable, from the tint resulting from the use of creosote "oil grade one" to the almost black shade of Van Dyke brown. These latter colors are especially attractve in combination with the brick or stone substructure.
The color of wooden garden features is a subject well worth considerable thought. White paint is used more frequently than any other and, although pleasing to the eye when the foliage is on the plants, it is most glaring and cold looking in the Winter season. Shades of green are good but do not afford sufficient contrast. On the whole, shades of brown and weathered oak tints will give the greatest satisfaction.
Fig. 154. - Stucco columns with rustic superstructure. - See page 193.
Fig. 155. - An attractive hardy border. - See page 197.