Design Ideas for Managing Rainwater in Your Garden Leave a comment

Whenever I am working to resolve water problems in a landscape, I must acknowledge that water will always win. The best we can do is creatively direct it toward the areas where we would like it to end up, with a focus on minimizing erosion damage and retaining as much water as possible for use on site. Plants can be part of the solution, and some erosion control systems even double as useful outdoor spaces like patios and walkways. Here are a few ideas to get you thinking about how you can manage rainwater in your own garden.

Plants that help with water retention and erosion prevention

Gro-Low sumac planted at top of slope
‘Gro-Low’ sumac has been planted through a mat woven from coconut fibers that will hold soil in place as the plants mature.

One of the simplest ways to manage rainwater in the landscape is with the thoughtful placement of planting beds. For example, plantings on steep slopes can be used to slow down water and prevent erosion. One of my favorite shrubs for this purpose is ‘Gro-Low’ sumac (Rhus aromatica ‘Gro-Low’ Zones 4–9). When installing a ground cover like ‘Gro-Low’ on a steep slope, you can provide additional erosion control by covering the bare ground between plants with a coconut-fiber mat. This biodegradable material will cover the ground effectively for several years until the plants grow together to form a continuous ground cover. Coconut-fiber mat is available in rolls at home improvement centers, farm supply stores, and from suppliers that carry stormwater-drainage systems and materials.

sloped landscape planted with various grasses
This woodland slope is stabilized by the root systems of Pennsylvania sedge (Carex pensylvanica, Zones 4–8) and a mix of fescues (Festuca spp. and cvs., Zones 4–9).

Another idea for planting on a slope is to combine plants with fibrous root systems that hold soil in place; these can be used in conjunction with plants that have abundant overhead branching or foliage to buffer rainfall from above. The best mixed plantings create appealing displays of color and texture and are very effective in controlling and absorbing rainwater. Most ornamental grasses have extensive root systems that are well suited for holding onto water. By combining them with low, spreading shrubs and summer-blooming perennials, you can create a vignette with multiple seasons of interest.

Direct water flow with hardscaping

granite cobblestone patio with bench
The wide gaps between these granite cobblestones give surface water a chance to soak into the ground instead of running off the surface.

When installing pathways, we can keep surfaces more permeable by using joint materials that allow water to pass through them. A pathway can take a form that is casual, formal, organic, or even geometric depending on the materials selected and how the designer uses them. Water can be allowed to flow through a space by way of the permeable path or be allowed to percolate into the soil, or there can be a combination of both. It all depends on how the designer uses the materials and adjusts the slope of the ground. The larger the gaps or the joints between pavers, the more permeable the path will be.

flagstone path cutting through lawn
In this informal pathway, turfgrass fills the spaces between flagstones to create a stable, walkable surface that is easy to maintain.

Joints can be filled with walkable plants such as turfgrass, moss, or ground covers, or inorganic materials such as sand, gravel, crushed shells, crushed glass, mulch, or soil. For larger volumes of water, engineered permeable paving systems can be used to create patios, formal sidewalks, and driveways.

stone swale cutting through mulched garden bed
This stone-lined swale efficiently channels stormwater when needed and serves as an attractive landscape element the rest of the time.

Water that flows quickly and in large volumes needs to be handled more seriously. In instances where plants are not likely to be effective for controlling erosion, it’s time to look at using stone to hold the ground. Boulders are perfect for retaining soil on natural slopes where one doesn’t want to build a formal wall. They can be tucked in where needed, and you can use whatever size works best for your situation. You can use stone slabs to build steps, with boulders holding the edges and keeping the soil from washing away during heavy rains.

pebble basin in foundation planting to catch water from gutters
In this foundation planting, stone was used to create a large pebble basin to catch water from upper-level gutters.

rain chain on side of house
For a roof corner with minimal water flow, a rain chain may be an alternative to the traditional downspout.

When it does show up, let’s try to be grateful for every drop of rain that falls on our gardens, preferably in a slow, steady, overnight shower that is over by morning. When that doesn’t happen, just sit back and smile. After all, what else can you do? You can’t control the rain.

Marti Neely, FAPLD, owns and operates Marti Neely Design and Associates in Omaha, Nebraska.

Photos: Marti Neely, FAPLD

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