This section is from the book "How To Make A Flower Garden", by Wilhelm Miller. Also available from Amazon: The Well-Tended Perennial Garden: Planting and Pruning Techniques.
ANY one who is planning to grow water-lilies will do well to study the conditions under which they thrive in nature. Water-lilies do not grow in every pond; they flourish only in places that are exposed to full sunshine, and which are not subjected to violent freshets or strong springs that keep the water cold even in summer time. Another thing, Nature seldom plants more than one species in one pond. Note also that natural ponds annually receive an accumulation of dead leaves, and that the surface water constantly adds silt, etc., to the accumulation of vegetable matter which furnishes abundant plant-food for nymphæas and other aquatic plants.
Water-lilies as cut flowers.
The location of the pond may first receive attention. A water-lily pond should be at a convenient distance from the dwelling-house and easy of access. Its near proximity to the dwelling-house can not be considered a menace, since mosquitoes may be kept in check by means of goldfish. If possible, select a site where the ground slopes gently toward the pond; but if the ground is level or nearly so, the soil taken from the excavation may be used to form a bank on one side or end, which, by judicious planting, will present a pleasing and natural effect. The water-level of the pond should be a few inches below the ground-line.
Having selected the site and decided as to the shape, it will be a wise policy to err on the side of making the basin too large rather than too small. If you have never grown water-lilies and do not know what "tropical vegetation" means, it will be difficult for you to realise how much space should be allotted a given number of plants. It is one of the commonest mistakes to crowd a great many plants into a little pool. Three water-plants are put into an ordinary tub, where there is not sufficient space for one. Of course there is a limit to the size of a pond, but I would suggest going to the extreme; it is far better than having to enlarge afterward, or having to content oneself with a pond that is too small. However, I should not advise any one to make a pond so large that it will be out of proportion with the rest of the garden.
The best way to make a pond will in most cases be the simplest and the most nature-like. Study the existing conditions in every case, and make use of the materials at hand. Clay, gravel, rough stones or bricks may be used for construction. Puddled clay will make a water-tight basin. The clay should be at least four inches thick on sides and bottom. If boxes or tubs are to be used, the bottom should be covered with sand, otherwise the soil may be placed on the clay bottom. Cover the sides with sod. There is much labour in constructing a pond of clay, and, although it may appear cheap, I would not recommend this method of construction unless the clay can be had for the digging and all hauling can be done without hiring teams. Gravel and like materials that can be used as concrete will answer the purpose well. The sides and bottom should be covered with four inches of the same, with a facing of Portland cement an inch thick. Rough stones laid in cement may also be used for the same purpose. The walls should be about eight inches thick, and finished with a facing of Portland cement; the bottom should be constructed in like manner. When the above-named materials are used, the sides should be flaring. The depth when finished should not be less than two feet.
The ground should by no means be new or made ground. A water-lily basin needs a solid substratum, so that settling in any part is out of the question, for should there be a leak the consequences will be disastrous. The best and most practicable method is to construct the basin of brickwork. This work may be entrusted to a local bricklayer, and an approximate cost can be given or ascertained beforehand. The walls should be eight inches thick, built perpendicular. The joints should be all well filled in as the work proceeds. The wall may be tapered near the top, finishing with a four-inch brick laid flat. The walls on the inside, as far as they are tapered, should receive an inch-thick plaster of Portland cement. The bottom, or floor, may be grouted or laid in with brickbats or whole bricks, and should afterward receive a good facing of cement.
The so-called "Egyptian" lotus (known to the trade as Nelnmblum apeclosum). Note that the leaves rise well above the water, while those of a nymphaea float upon the surface. The plant here pictured is the Indian lotus, or Pythagorean bean; the true Egyptian lotus, Nymphaea lotus. Is practically not in cultivation.