How to Build a Rain Garden in the Landscape

This rain garden was constructed on a previously flat property in Water Mill, Long Island NY.

Our project goal was to transform a wide open landscape into an intimate space with detailed retaining rock gardens and a diverse sustainable deer resistant planting.

The first consideration was the root system of a mature oak tree. The excavation zone and the retaining rock garden shape was determined by the root system profile. Retaining was  necessary at the sides of the rain garden but we were able to slope the grade leading into and out of the garden.

The next consideration was the rain garden liner and shape. A heavy duty liner was chosen to be able to withstand the wetland and walkway construction. The liner was extended all the way up to the retaining rock to provide moisture to the lower rock garden plantings as well as providing humidity to the moss areas.

On this project we developed a zig zag walkway to provide access directly through the rain garden. This design provided an easy walking surface with interest that enables a visitor to go right down into the garden. The wood walkway is constructed on top of the rubber liner with padding and cement footings.

Before the garden is back filled we sloped all the property drainage into the rain garden as well as the roof water. Overflow level was established with overflow weep holes feeding several plant pockets and the remaining overflow water is plumbed into the existing roof water dry wells.

Wetland plants require different planting soil. The bulk of the rain garden is back filled with sand 6″ to 12″ below the underside of the walkway (depending on the plants water requirements) with the individual planting pockets amended for each plant. The wetland plants were chosen for flowering time, height, shape with some evergreen perennials for winter interest.

The rock gardens were planted with drought resistant alpines and the remaining landscape was planted with deer resistant plants such as Cephalotaxus, Pinus mugo, Leucothoe, Picea, Cornus, and Magnolia.

The garden paths and walkways were covered with medium fine gravel to provide a comfortable walking surface and to prevent erosion into the rain garden.

Visit the rock garden canyon that Emil Kreye & Son inc. installed at Long House Reserve in East Hampton NY. LONGHOUSE SITE