How to Build a Rain Garden in Eugene, Oregon
How to Build a Rain Garden in Eugene, Oregon
Transform your landscape into a functional stormwater management system that reduces runoff and filters pollutants before they enter Lane County's waterways. This guide provides a sustainable approach tailored to the region's heavy seasonal rainfall and clay-heavy soils.
What You'll Need
- Shovel and garden rake
- Wheelbarrow
- Soil test kit (to determine infiltration rate)
- Native rain garden plants
- Organic mulch or shredded bark
- Measuring tape and marking paint
Steps
Step 1: Site Selection
Choose a shallow depression where runoff naturally collects, ideally 4 to 10 feet away from your home's foundation. Ensure the location is not directly over a septic tank or underground utility line.
Step 2: Perform a Percolation Test
Dig a hole and fill it with water to see how quickly it drains. Because many Eugene neighborhoods have heavy clay soil, you may need to amend the soil with compost or sand to ensure water infiltrates properly.
Step 3: Map and Mark the Area
Use marking paint to outline the garden's perimeter, typically shaping it as an oval or kidney bean. Ensure the garden is positioned to intercept water flowing from a downspout or a natural slope.
Step 4: Excavate the Basin
Dig out the soil to create a basin roughly 6 to 12 inches deep. Save the excavated soil to create a berm on the downhill side of the garden, which prevents water from escaping too quickly.
Step 5: Amend the Soil
Mix the native soil with organic compost to improve drainage and nutrient levels. This creates a healthy environment for root systems to anchor and filter pollutants from the stormwater.
Step 6: Select Native Plants
Choose a variety of native Oregon species that can tolerate both saturated soil and periods of drought. Group plants by their water needs, placing the most water-tolerant species at the center of the basin.
Step 7: Plant and Mulch
Install your plants according to their spacing requirements and cover the remaining bare soil with 2 to 3 inches of organic mulch. This suppresses weeds and prevents the soil from eroding during heavy winter rains.
Expert Tips
- Avoid using synthetic fertilizers, as these can wash into the storm drain and counteract the garden's filtration purpose.
- Focus on deep-rooted native perennials, which are more effective at absorbing water than shallow-rooted grasses.
- Check your garden during the first few heavy rains to ensure water is pooling and draining as intended without overflowing into walkways.