Water offers such a wide variety of applications that no garden can be considered too small, no style too restrictive and few budgets too meager to accommodate some kind of water feature.
When introducing water, spend time considering why you want it in your garden, then plan how it can best be integrated into the garden’s existing design scheme. Take into account the nature of movement and sound that moving water features can offer — these elements need to be applied with just as much care as color and texture in a planting scheme. Adjustable flow controllers on the outlets of pumps for fountains and waterfalls enable the pressure and volume to be finely tuned — too much noise can be obtrusive; too little and it becomes irritating. Cobbles in shallow water at the base of waterfalls create a totally different sound from water falling into deeper water.
Two popular misconceptions must be dispelled at the outset in planning a water feature. First, moving water needs no connection to the main water supply. Second, ponds are not necessarily more appropriate in areas of high rainfall — they provide welcome oases in dry climatic zones.
The considerations of site will be discussed later, but first let’s look at some main types of pond.
Formal pools. A formal pool is often the ideal option for a small garden where there is little or no lawn and the surface is dominated by paving. The formal pool has clearly defined, crisp edges, which are generally paved and form regular geometric shapes. The planting is restrained, confined mainly in aquatic planting containers, and dominated by specimen plants that have bold upright leaves, such as irises, which create a strong vertical contrast to the even, horizontal expanse of the water.
Informal ponds. The priority in planning an informal pond is to blend it into the existing style of garden design. This type of pond would have strong appeal to the gardener, offering considerable scope for lush planting which may not be possible in other parts of the garden. The boundaries of the pond could be extended to a bog area, so allow space for this at the planning stage. If fish are introduced, the choice, size and number will need to be strictly limited.
Raised pools. These are similar to formal pools in their suitability for small spaces and being surrounded by paving. For small or patio gardens surrounded by high fences or walls, pools introduce reflected light to counteract any feeling of restriction. One of the great pleasures of a raised pool is to be able to sit on the pool surround and enjoy the water at close quarters. Raised pools combined with a fountain are very suitable for fish because the fountain spray oxygenates the water in summer months.
Ponds for Fish. If you aim to keep fish in a pond, it is important to resolve the practical issues of good fish husbandry at the initial planning stage in order to avoid problems when the fish are introduced. The serious fish-keeper’s requirements are vastly different from those of the gardener and include an increase in the amount of equipment such as pumps and filters as the fish increase in size and number, as well as the necessity of easy cleaning on a regular basis. Small fish grow into big fish, particularly where koi carp are concerned, and large koi are not the most suitable partners for ornamental water plants. Oxygenating plants that may be adequate for a small ornamental pond will not supply the needs of big fish.
Wildlife pools. These provide a constant source of interest, even in the winter months when the foliage dies back and the water surface lures bathing birds to the shallow edges. Providing these shallow bathing edges at a point that can be seen from the house is an important part of the planning process. A beach-like edge is not only important for bathing birds but also provides the vital means of entry and departure for amphibians. If the background to the garden is rural, wildlife pools help blend the countryside into
Canals. These also are suitable for formal settings. They use running water to form shallow, narrow streams which can include changes in heights if the garden is sloping. On a level site, the canal forms a long, slender formal pool, generally without plants, which in addition to making a strong visual statement in a balanced garden design introduces a fine thread of reflected light.
Fountain pools. Fountains contribute the delightful sparkle of light and the sound of moving water to pools. They can be used in both formal and informal pools but are most appropriate for formal ones.
Fountains display the full beauty of the light spectrum, making them the ideal centerpiece for formally designed gardens, particularly when there is also an ample clear water surface that reflects the symmetry of the surrounding garden and emphasize its parallel lines.
Fountain spouts also can add interest to walls, where a variety of self-contained or tiered fountains spilling into a base pool can be introduced.
Streams and waterfalls. A slow, meandering stream will add enormous interest to a garden with the most modest of slopes and will allow an expanse of lawn to be broken by movement and lush planting. Where there is sufficient slope, a faster-moving stream bordered by rocks offers the opportunity to plant alpines near the stream edge. Creative gardeners are in their element here, building small rock pools and fashioning babbling sounds as water tumbles down rills.
Self-contained water features. Half barrels, old sinks and sandstone troughs are just a few of the containers that can bring water gardening into small spaces. In addition, there are an increasing number of self-contained kits that use tiny pumps to recirculate water through containers such as urns and cast-iron hand pumps. They easily can be incorporated into any style of garden, introducing sound and movement at the touch of a switch.
Before taking the final step of choosing a site for the pond, you’ll want to consider some guidelines relating to its size, relative dimensions and profile.
Size. The general rule is the bigger, the better. This is because the larger the pool, the easier it is to manage as time goes on. In addition, most pool owners will admit to wishing they had built a larger pool because they do not have enough room to introduce new plants and/or their fish have outgrown the pool.
The smaller the pool, the more likely it is to have problems of green water, excessive temperature fluctuation and inadequate oxygen for the fish. If possible, try to achieve a minimum surface area of 50 to 60 square feet.
Proportions and profile. Size is linked to depth. No matter how large the surface area is, if the pool is only 3 to 6 inches deep, it will be a disaster. The ideal depth of medium-sized ponds with a surface area of 50 to 200 square feet is 2 feet. Ponds less than 50 square feet may be 15 to 18 inches deep. Ponds larger than 200 square feet would benefit from a depth of 30 inches. The reason for these guidelines is related to the needs of green algae. Algae thrive in warm, shallow water in full sunshine. Deeper water allows for a greater volume of water that is not in the susceptible top 6 inches where the algae thrive in the warmer and lighter conditions. The larger water volume also acts as a buffer to rapid and frequent temperature fluctuations, which are detrimental to many forms of pond life.
The relationship of depth to surface area is only valid when a pool has near to vertical side walls. In pools with a shallow, saucer-shaped profile, the volume can be reduced by as much as a half and an algae-free pool becomes more difficult to achieve because the water temperature remains more conducive to algae. Smaller ponds with marginal shelves all the way round the sides also have a reduced volume, so it’s better to restrict these shelves to where planting is necessary rather than build them around the entire pool. Ornamental ponds need be no deeper than 30 inches no matter how large the surface area.
Other Positioning Factors
With the concerns of size and profile in mind, the process of selecting the site for your water feature can begin. It might appear obvious to put a formal pool on the patio near the house or an informal pool at the lowest point of the garden, but to ensure that the best possible location is identified, consider the following points.
Shade. The pond should receive enough sunshine to warm the water and bathe the submerged plants in adequate light. The range of aquatic plants that can be grown in shaded pools is quite limited, and water lilies are reluctant to flower in these conditions.
Shade from trees is particularly troublesome because it is associated with leaf fall, which leads to a thick layer of decomposing vegetation on the pond bottom if not caught by netting (plastic mesh) placed over the surface. As this vegetation decomposes, it produces methane gas, which is harmful to fish. It is especially important to prevent the leaves of yew, holly and laburnum sinking to the pond bottom since they are poisonous to other plant and animal life in the water. Although conifers may seem to be less of a problem, their leaves are constantly falling and depositing fine dusty bud scales on the water surface.
Wind. Wind cools the water surface, blows fountain spray and damages the soft, succulent stems of marginal plants. In an attempt to capture the maximum amount of sun in a small garden, the pool is often sited in the center of the lawn where it is more prone to wind exposure. Shelter can be provided by a trellis or planting on the pool’s windward side. Any artificial windbreak should be semipermeable rather than solid panels to prevent eddying and turbulence on the side away from the prevailing wind. Position the windbreak a little distance away from the pool, since the optimum effect at ground level of trellis or lath-like structures is felt at seven to ten times the height of the windbreak on the lee side.
Frost. Cold air accumulates in low-lying pockets, making plants more susceptible to browning by spring frosts. Informal ponds are often sited in low-lying areas because that is where they look more natural, making them more susceptible to frosts. Site your pond slightly higher up the dip in the land.
Sloping ground. A steep slope need not be too much of a constraint if the pond is partially dug out of the bank and partially banked up on the lower side. The outline of the pool needs to be slender and follow the contours of the slope. On land falling away from the house, build up the surround on the lower side of the pool so the pool surface can be seen more easily. If the land rises from the house, cut more into the bank side so the view is not spoiled by a high retaining wall.
Water table. The water table is the level at which water will stand in a ground hole or well. The level of the local water table rises and falls with the seasons and can be affected by large-scale building works or drainage schemes in the neighborhood. Most water tables are well below the level at which a pond will be dug, but occasionally it may be a problem on wet, heavy land. A test to check if there is a high water table can be carried out by digging a hole 2 to 3 feet deep and leaving it for a day or two to see if water appears in the hole. If water lies near the surface, there could be problems, since pond liners can billow up to the pool surface as a result of water pressure from the water table beneath.
Underground hazards. Once you have narrowed down your siting options, it is vital to ensure that a sunken pool will not be positioned over the route of underground services such as drains, gas pipes, water pipes, electricity cables and telephone cables. Before you dig, contact the appropriate utility company, which will have the equipment to pinpoint the underground line.
Fine Tuning the Site
The ideal site probably will involve some compromise. For instance, high on your list of priorities may be the ability to see the feature from a frequently used window of your home. Your choice may also be influenced by the desire to reflect any garden features such as ornaments or trees in the water. Sketching out a siting plan that identifies shade, prevailing wind direction, services and viewing lines from the windows is step one before finally taking out a garden hose to lay on the ground and outline possible sites. Lay a full-length mirror flat on the ground inside the hose to simulate the effect of the water surface, then see what reflections appear. If these are to be enjoyed from a particular window, take time making minor adjustments to the proposed position of the pond for the best view. A movement of 2 to 3 feet on the ground makes a great difference in the angle of reflection and how well the feature is framed.
Identify the optimum site, decide how important an electricity supply is at the pool side. If a pump is vital and the distance makes this prohibitive in terms of cost, it may mean a final alteration to the site.
When excavating in an area of lawn or rough turf, the top layer of turf should be removed first and, if space is available elsewhere in the garden, the turves stacked upside down in a neat pile. After a few months rotting down they will produce a fibrous loam, which is ideal for potting aquatic plants. The next layer, 12 to 15 inches deep, is topsoil, which also is valuable as a potting medium for aquatics or a top-dressing on the borders. This soil will prove invaluable if some slight alterations need to be made to the contours around the pool once it has been installed. The bottom layer, which is generally a different color from the topsoil, is subsoil and should be discarded unless significant changes in level are anticipated.
A mound can be created near the pool to make a base for a stream, but if on a flat site, make sure the mound doesn’t look too contrived by keeping the proportions and gradient as natural-looking as possible. The height of the mound should be no more than one-fifth of the width, with gently sloping sides.
Very rarely the unforeseen problem of water seeping into the excavation occurs. This usually happens on wet, heavy land, particularly in winter. Head this problem off by checking the level of the water table on wet soil (see above). But where there is still a problem, one of the options below will remedy the situation:
• Raise the proposed level around the pond by adding extra soil.
• Move the pond site to higher ground if available.
• Build a raised or semiraised pool on the site.
• Try to drain the area around the proposed pond.
• Pump the water out of the excavation, then install a heavy fiberglass pond unit weighted down inside with bricks or concrete blocks.
A drain plug is not necessary in the bottom of ornamental ponds; there is always the risk that it may not be 100 percent watertight. Such a plug is only necessary in fish ponds where stricter hygiene and regular cleaning are required.
Excerpted with permission of Sterling Publishing Co., Inc. from Pond Basics: A Step-by-Step Guide for Water Gardeners (copyright 2000 Octopus Publishing Group) by Peter Robinson. To order, please select BOOKSHELF.