How To Create a Rain Garden

Rain gardens are eco-friendly landscaping solutions that use natural plants to manage stormwater runoff. These gardens capture rainwater from roofs, driveways, and other impervious surfaces, and filter it into the ground slowly. They also add natural beauty to yards. Learn how to prepare, install, and maintain your own rain garden in our guide below. 

Understanding Rain Gardens

Rain gardens mimic natural water filtration processes. They collect rainwater runoff and guide it into the soil to percolate, which reduces the amount of water that flows directly into storm drains and waterways. This process helps filter out pollutants, recharges groundwater, and offers insects and wildlife additional habitats. Rain gardens don’t require much maintenance.

Are Rain Gardens Worth It?

Rain gardens are worth the investment for most homeowners. They manage stormwater efficiently and benefit the environment. Rain gardens can also reduce water-pooling and erosion problems in areas that get frequent rain or areas that face drainage issues.

What You’ll Need

You’ll need the materials below to start your project: 

• Downspout diverter
• Four-way soil mix
• Landscape fabric
• Marking paint
• Metal screws
• Mulch
• Rain garden-friendly plants
• River rocks

Planning Your Rain Garden

Plan your rain garden very carefully before you start digging. Consider factors such as location, size, and accompanying plant selection before you commit to a model. The rain garden should function efficiently and complement your landscape.

Choosing the Right Location

Think about your home’s layout and features when selecting a suitable spot for your rain garden. It must be near a downspout, and it should be at least 10 feet away from your home’s foundation if you have a basement. It should be at least 2 feet away if you don’t. Keep it at least 3 feet away from driveways and streets, and at least 2 or 3 feet away from pathways. The area should have a slight slope that can direct water, but the flow should not be too steep.

Determining the Size

The size of your rain garden depends on the amount of runoff you anticipate it will capture. It should be about 10% of the size of the roof area from which it’s capturing water. If your roof area is 350 square feet, for example, your rain garden should be at least 35 square feet.

Selecting Plants

The right plants can make your rain garden even more successful. The plants must be able to thrive in both wet and dry conditions. Some suitable options are below.  

• Deciduous and evergreen trees
• Flowering perennials
• Grasses
• Shrubs

Choose plants that are native to the area if you can, as they will require less maintenance than other types. They will also provide food and habitat for local wildlife, which will enhance your garden’s biodiversity.

Preparing the Site for a Rain Garden

Conducting a percolation test will help you understand your soil’s drainage capability. Here’s how to perform this test:

1. Dig a hole that’s about 12 inches deep and wide.
2. Fill it with water.
3. Determine how quickly the water drains.

The ideal drainage rate is at least a 1/2 inch per hour. If your soil doesn’t drain well, you may need to amend it or choose a different location.

Once you land the ideal soil drain rate, use spray paint to outline the shape of your rain garden, and begin digging the basin. Make it deepest in the center, and gradually raise the slope up to the edges. Then, create a berm around the downhill side of the garden using the excavated soil.

Installing the Rain Garden

Once you have properly prepared the site, you can begin installing your rain garden. Follow the steps below.

Amend the Soil

Incorporate a four-way soil mix into your site’s existing soil to improve drainage and provide nutrients for your plants. Loose soil encourages better water filtration and root growth, so avoid compacting the soil.

Create a Water Inlet

Follow the steps below to direct water from your downspout to the rain garden:

1. Install a downspout extension or diverter.
2. Dig a shallow trench from the downspout to the rain garden.
3. Line the trench with landscape fabric.
4. Fill the trench with river rocks to create a decorative water channel.

Plant Your Rain Garden

You can begin planting your rain garden. Follow the steps below. 

1. Arrange plants based on their moisture tolerance, and place the more tolerant plants in the center. 
2. Dig holes that are twice as wide as the root balls.
3. Plant the root balls as deep in the soil as they were deep in their containers.  
4. Water each plant thoroughly.

Finish this process by applying a 2- or 3-inch layer of organic mulch around the plants, which will help them retain moisture and suppress weeds. Use the excavated sod to create a slight berm around the garden’s edge, which will help the garden retain water. Water your new plants regularly during the first growing season.

Maintaining Your Rain Garden

You’ll only need to perform occasional maintenance on your rain garden once you’ve installed it. Follow the tips below.

• Prune plants to maintain their shape and size
• Remove sediment from the inlet area
• Replace mulch annually
• Remove weeds as needed
• Water during dry periods for the first year

Do Rain Gardens Attract Mosquitoes?

If you properly install your rain garden, it should not attract mosquitoes. Rain gardens are designed to drain within 24–48 hours, which is less time than mosquitoes need to complete their breeding cycles. If water stands for longer periods of time, you need to adjust the garden’s depth or improve soil drainage.

Common Rain Garden Challenges

Rain gardens are generally low-maintenance, but you may encounter some of the challenges below.

Erosion

Your rain garden might eventually start to erode around the inlet. Combat this by adding more rocks or plants to slow water flow and stabilize the soil.

Plant Die-Off

Not all plants will thrive in a rain garden. Replace struggling plants with species that are better suited to the area’s specific moisture conditions.

Clogging

Sediment may accumulate in the inlet area over time. Remove this buildup occasionally to make sure water can flow freely into the garden.

Tools