Creating a Naturalistic Informal Water Garden

The Essence of Informal Water Gardens

An informal pool should look natural and blend into the landscape—unlike a formal pool that stands isolated as a focal point. The open water, alive with waterlilies, may be a focal point but is also the centerpiece of a planting scheme flowing naturally outward.

Success hinges on plants and features tying the pool to its surroundings. Common links are rock gardens or bog areas. Rock gardens often result from dumping excavation spoil and adding rocks—a heap of subsoil with protruding rocks rarely looks natural or suits alpines.

Excavated soil should be removed; rock features built independently to mimic a moraine—accumulated rocks and free-draining soil. If a sloping area exists behind the pool, redistribute spoil to create a natural landform spilling into the water, using hard rock like millstone grit that won't flake when frosted.

Bog areas should be developed during pool construction—easier to incorporate and scale. Effective bog gardens need at least half the pool's area, but can be two or three times larger.

Informal pools can take almost any shape; kidney and dumbbell are popular pre-formed shapes. Other construction methods offer good planting opportunities. Natural materials are essential—concrete or concrete paving destroys the informal effect. Natural stone provides visual relief; genuine York paving blends naturally despite its formal appearance.

Edge treatment determines the natural look: disguised by planting or accentuated with hard materials. Natural paving, rocks, wood, and cobble beaches all add value if used discreetly.

Planting: The Heart of Informal Design

Planting determines success—unrestricted arrangement creates informality. If the pool shape suits cultivation, scale fits the garden, and it's linked by bog or rock features, planting is everything. A well-planned informal garden grows a wide plant range—often the main reason for the feature.

Plants must appear relaxed and untroubled, but this requires attention to detail. Proportions and vigor must suit the space. In small pools, avoid tall reedmace (Typha); use Typha minima (under 45 cm/18 in) for fat brown pokers without management battles.

Avoid creepers that jump containers—Lysimachia nummularia disguising pot tops is fine, but water mint (Mentha aquatica) and brooklime (Veronica beccabunga) invade even isolated containers and swamp unrestricted margins. Deprive free-seeders like musk (Mimulus) and water plantains of flower stems immediately. Common rushes also self-sow generously.

Plant combinations are personal taste, but consider flower and foliage contrasts, and the beauty of solitary specimens against water, especially centrally. A waterlily is majestic on still amber water but lost among encroaching marginals or exuberant floaters.

With heavily planted margins extending into bog areas, simplicity in open water is key. Choose waterlilies with plain green leaves and single-colour blooms—avoid mottled foliage or colour-changing flowers. A simple white or pink, heavily fragrant waterlily provides stability, dignity, and an essential focal point.

Margins and bog gardens should merge seamlessly. Marsh marigolds, umbrella leaf, and Himalayan cowslip bridge both zones. Marsh marigolds flower earliest, bringing spring sparkle—use bold mounds as focal points, positioned so other vegetation takes over as they fade. Follow with aquatic irises: bold sentinels with midsummer flowers in wide colour arrays; use upright sword-like leaves for summer structure, uncluttered by looser plants.

Optimizing Conditions and Theming

For plant diversity, create optimal conditions for wellbeing and harmony. Most aquatic and bog plants share easy-to-achieve soil/water conditions. A few demand acidity—cotton grass (Eriophorum angustifolium), Japanese clematis-flowered iris (Iris ensata)—achieved by isolating root systems unobtrusively.

Theming unifies diverse collections. Group by flowering times and mutual support—how mid-season plants complement early bloomers, later ones disguise fading foliage without swamping. Ensure all get sufficient light. Overall themes: ferns in gloomy areas, candelabra primulas on sunny peninsulas, giant-leaved contrasts like skunk cabbage and gunnera, grasses and decorative reeds together. Theming turns a stamp collection into a pleasing scheme.

Managing Open Water

Open water space matters. Waterlilies, water hawthorn, and water fringe need surrounding open water—retain it, regularly remove encroaching floaters. Keep submerged aquatics (Ranunculus aquatilis, Hottonia palustris) away from deep-water aquatics that punctuate the surface with floating leaves and flowers—charming but cluttering.

Contain floating plants in one area if possible; don't let them invade others' space. Even sparse open water lets the pool stay attractive and allows margins/bog to be less ordered without looking awful.

On marginal shelves and bog gardens, prioritize structural planting: giant-leaved Gunnera manicata, royal fern (Osmunda regalis), decorative rush (Schoenoplectus lacustris tabernaemontani 'Albescens'). If these provide background or focal points, other plants become dressing.