© HM Government
Synonyms: Eco-friendly water garden, small natural drainage system, SuDS
Shallow depression planted with deep-rooted native plants and grasses, located near a runoff source (like a downspout, or driveway). Designed to capture rainwater runoff and stop the water from reaching the sewer system.
Rain gardens are relatively small, planted areas designed to receive rainwater flowing from paved surfaces or from drainpipes. In its simplest form, a rain garden is a shallow depression, partially filled with absorbent, yet free draining soil (usually a mixture of coarse sand, grit, and organic matter) and planted with vegetation that can withstand temporary inundation.
Rain gardens are designed to intercept and slow the flow of water that might otherwise directly enter conventional drains. The microbes in the soil break-down pollutants. Water enters the rain garden and infiltrates into the soil, to be taken up by plants and released back into the air through evapo-transpiration. Depending on the permeability of the subsoil, and the underlying geology, a certain proportion of the water entering a rain garden may percolate into the ground. Once full, and depending on the topography, rain gardens may overflow into other rain gardens, rills, channels, swales or into the conventional drainage system (Source: Natural England).
Key Species:
See this guide (non-Government) for planting suggestions.
Assessment Questions:
- Is the site a garden located near a source of runoff, such as a downspout, driveway, or sump pump?
- Does the garden feature a shallow depression or basin-like shape?
- Has the garden been designed to capture rainwater runoff and stop water reaching the sewer system?
If YES, then it is likely 'Urban - Rain Garden'
How to Create / Enhance to a "Good" condition
They are more suitable for houses with larger front gardens as they require space and need to be located a suitable distance from buildings (Source: HM Government).
When designing rain gardens, it is important to consider any constraints such as below-ground utilities and archaeology, as well as how water will drain away once storage capacity is exceeded. Raised planters, planter boxes, stormwater planters, or SuDS planters, which receive water directly from a downpipe are also sometimes described as rain gardens. The inlet of a rain garden may be armoured to prevent erosion. The most water-tolerant plants should be located near the inlet or in the lowest part of the rain garden and plants that can tolerate both wet and dry conditions elsewhere. Planting a rain garden presents an opportunity to increase biodiversity by using native species or non-native species that attract pollinators (Source: Natural England)
Please refer to this guide for further information.
How to get a "moderate" rating
In a management plan aiming to achieve a ‘moderate’ condition, the plan will show:
The garden will have a variety of flower species attracting insects like bees and butterflies and other wildlife. Plants will be chosen that are appropriate to the size and design of the rain garden and, wherever possible, shall be native species and selected soas to produce flowers during different times of year, (thus providing nectar through all seasons).
The planting mix will exclude invasive non-native species (INNS)
There shall be no species that are listed on Schedule 9 of the Wildlife and Countryside Act 1981 (as amended) or those listed by the local planning authority as invasive species.
How to get a "good rating"
In addition to the characteristics for moderate condition, to get a ‘good’ condition the plan will include these features:
Management of the garden will ensure a varied vegetation structure, with at least two physically different habitat elements or vegetation types or heights. These different vegetation structures will provide habitat for a range of animal species (both vertebrates and invertebrates).
No single vegetation type will cover more than 80% of the habitat area.
Useful Resources
Guide 1 - UK Rain Garden Guide
Guide 3 - How to Create a Rain Garden
Please note that this is a simple guide to help identify the habitat. For a definitive description, please refer to UKHab documentation. Joe's Blooms takes no responsibility for the content of external links.