A formal water feature tends to depend upon rather rigid, or mathematical, principles to which the planting must conform. Although there are few aquatic plants that really lend themselves to such order, either in appearance or habit, the combination of careful plant selection and tightly controlled planting can produce the desired effect.

To provide height and focal points within a pool, choose from the various schoenoplectus. The common bulrush (Schoenoplectus lacustris) is first class, but do not select the type that produces large, brown poker-like heads, which is really a reedmace. S. lacustris has slender dark green stems, which are like large knitting needles. Often used in the wildlife garden, and a poor relation of the zebra rush (Schoenoplectus lacustris tabernaemontani ‘Zebrinus’) and Schoenoplectus lacustris tabernaemontani ‘Albescens’, which it closely resembles, it can provide sombre structure where others fail. It is not a plant for general decoration, but in such circumstances, or the wilderness of a wildlife pool, it has its uses.

If the pool is to look really sophisticated, Schoenoplectus lacustris tabernaemontani ‘Zebrinus’ and ‘Albescens’ are naturals, providing bold upright structural foliage of high quality, which can only he equalled for effectiveness by some of the cultivars of Iris laevigata. The variegated foliage of  Iris laevigata ‘Variegata’ is extremely effective. Forget the blue flowers, although these are a bonus during early summer, and plant for the effect of the handsome sword-like leaves.

Variegated sweet flag (Acorus calamus ‘Variegatus’) does not produce significant flowers, but really high-quality, cream, green and rose-tinted leaves. Although not evergreen, its foliage will be in evidence for much of the year and has a very pleasant tangerine fragrance.

Bold plants like these should be used as focal points within the pool or as a means of providing height to the scheme. When matching plants that will grow side by side, select material of similar age and condition, planting it in a uniform compost in containers of the same size. This is vital when trying to achieve a symmetrical display. The same applies to waterlilies, especially when attempting to match pairs in a still open stretch of water.

 

ORIENTAL PLANTING IDEAS

Not all formal pools will follow traditional Western ideas. With the increased interest in keeping koi carp, Oriental themes have become very popular. These depend for their success upon the combination of landscape materials, such as cobbles, paving and gravel, and very specific planting. Although the plants chosen do not have to originate from the Orient, they must conform with the overall theme and, in most cases, should be able to stand alone.

The dwarf reedmace (Typha minima) is a classic Oriental plant, while the zebra rush (Schoenoplectus lacustris tabernaemontani ‘Zebrinus’) has all the desired qualities. All the Iris laevigata cultivars are true Orientals and, for the bog garden, Iris ensata fits the bill. Hostas, especially the variegated kinds and the large-leaved Hosta sieboldiana var. elegans, are perfect for the moist edge of an Oriental water feature, particularly when backed by the bold leaves of Darmera peltata.

 

CHOOSING A THEME

As with informal plantings, a formal pool can be themed to a particular colour or colour combination. Fewer plants will be required, but you will need more than one example of each. In a simple square or rectangle of water, with provision for marginal plantings in each corner, select the lovely upright foliage and greenish spathes of Peltandra virginica to mix with the oval or spade-like leaves of the water plantain (Alisma plantago-aquatica), which has spreading panicles of pinkish-white blossoms. For the open water, choose a simple white-flowered waterlily such as ‘Hermine’. If desired, the water chestnut (Trapa natans) can be added, but this floating plant will not necessarily remain in the same place and may detract from the overall symmetry of the arrangement.

If a pink and white theme does not appeal, look to a yellow and white combination. Fill a container with early flowering, bright yellow marsh marigold (Caltha palustris) and the low growing, summer blooming brass buttons (Cotula coronopifolia). Alternatively, plant baskets solid with Mimulus luteus. As a centre-piece, use either a bright yellow waterlily like ‘Marliacea Chromatella’ or a very classy white, such as a’ Virginalis’ or ‘Gronnère’

Consider fragrance as part of your planting scheme, especially if the pool is in an enclosed area, such as a courtyard. Perfume will tend to linger in the warm still atmosphere and make a significant contribution to the pleasure of the pool-side experience, especially if accompanied by splashing water. Choose a fragrant waterlily like ‘Rose Arey’. This is very free flowering and has a rich aniseed fragrance. It should be grown in isolation from other scents so that its cloying richness can be enjoyed to the full. Treat the water hawthorn (Aponogeton distachyos) in a similar fashion. Its heady vanilla fragrance is best enjoyed alone.

With raised pools, scented foliage can be enjoyed more readily because the leaves will be easier to touch. It is not advisable to grow scented plants in close proximity to one another, as might be expected in a herb patch, for the smell of each may be overwhelmed by its neighbours. In most cases, it is preferable to grow them individually and to enjoy their fragrance in isolation. Choose from water mint (Mentha aquatica), the sweet flag (Acorus calamus) and the unusual, but spicily aromatic, Mentha cervina. All have leaves that release pungent aromas when touched on warm days.