Rain Gardens: Managing Water Sustainably in the Garden and Designed Landscape

Every bit as appealing as its title, Rain Gardens tells us what to do as we find ourselves in a built environment where much of the earth is paved over and our supply of cheap water is diminishing. If you have grown up thinking that gardens were earth based, this “hortus” may take some getting used to. It will also delight you, as you learn how rain gardens can mediate the extremes of drought and deluge while enhancing the beauty and ecology of our commons.

When managing water drives design, impermeable surfaces become the means of capturing water for the garden. Plant selection takes on wider implications, as vegetation schemes are chosen for their value in mediating impacts from the middle ranges of moisture through temporary dryness.

Begun modestly in Maryland in the 1980s, rain gardens have since become widely popular. Authors Nigel Dunnett, a lecturer and writer, and Andy Clayden, a landscape architect and lecturer at the University of Sheffield in the UK, have traveled from Oregon to Austria to gather and assess examples. The plentiful and lyrical photographs record for us many kinds of rain gardens, from small shed roof to large-scale urban park, that are engaging, appealing, fun, and functional without looking engineered.

Learning the terms and concepts of stormwater management, such as bioretention and acre-feet of water moving across a paved surface, takes time. Happily, the authors have organized this book so that you easily understand. They walk you through the process, holding your hand. At the end, you know how to design a garden that exemplifies the most profound and playful qualities of water in a garden setting.

In the first of its three sections, Rain Gardens covers the notion of sustainable landscape, water in a changing climate, bioretention, and the stormwater chain. Rain gardens can be both beautiful and beneficial to the environment. The term includes all elements that capture, channel, divert, or utilize rain that falls on a property. We are taken into a more intimate and lively relationship with water herself, in landscapes that enhance biodiversity as they bring visual and sensory pleasure while mediating drought, destructive storms, and rising sea levels. Rain garden landscapes are planned to provide real solutions to water-related problems; each individual’s small-scale actions can have a real impact.

In The Stormwater Chain, the authors advise us to pay attention to where and how stormwater lands on a property and where it goes. You can mediate the stormwater chain with bioretention facilities and green roofs, or by capturing run-off and disconnecting downpipes.

Green roofs can potentially reduce the runoff from small to moderate storms by as much as forty to fifty percent in a given area. Success depends on how well those with roofs can collaborate on neighborhood solutions. Implementations range from commercially produced sedum mats to wildflower meadows. Rain chains, stormwater planters, landscape swales, filter strips, retention ponds, infiltration gardens, and swimming ponds are all strategic garden options that engage stormwater.

In the concept of “swimming ponds,” Professor Wolfram Kircher, a German plant researcher, addressed a major historical problem: “. . . conflict between needing low levels of nutrients to prevent algal blooms and murkiness for swimmers, and growing plants in common use for the regeneration (ie, filtration) zone.” He found his solution in low-nutrient wetlands, bogs, and fens. By drawing inspiration from these situations, the plants that extract and reduce nutrient loading could be balanced, on the swim pond edges, with artificial bog vegetation: an exciting mix of grasses, insectivorous plants, dwarf shrubs, heaths and bilberries, orchids, and delicate wetland species.

The Plant Directory concludes the book with a twelve-page chart cataloguing herbaceous plants, grasses, shrubs, and trees on a grid that rates them as wet, moist, mesic, or dry. “Typical rain garden plants will . . . be found in situations around water bodies or in areas of moist soil, or from habitats that are subjected to, and soak up, significant amounts of rainfall during part of the year.”

The authors have created an appealing, educational, practical, timely, and inspiring book. Of value to the landscape professional as well as the home gardener, Rain Gardens offers hope for all concerned with improving the stewardship of our environment.

Katherine Cook, garden designer and restorationist
San Rafael, California