How to Build a Rain Garden in Eugene, Oregon
How to Build a Rain Garden in Eugene, Oregon
Create a sustainable landscape feature that captures stormwater runoff and protects Lane County watersheds by filtering pollutants before they reach the Willamette River.
What You'll Need
- Shovel and garden rake
- Wheelbarrow
- Soil test kit (to check percolation rates)
- Native rain garden plant mix
- Mulch (shredded hardwood or cedar)
- Measuring tape and marking paint
Steps
Step 1: Site Selection
Identify a natural low point in your yard where runoff collects, ensuring it is at least 10 feet away from your home's foundation. Avoid areas with high utility lines or those too close to septic systems to prevent structural damage.
Step 2: Percolation Testing
Dig a hole 12 inches deep and fill it with water to see how quickly it drains. In Eugene's varied soil, a rain garden is most effective if the water drains within 24 to 48 hours; if it takes longer, you may need to amend the soil with sand or compost.
Step 3: Marking and Excavation
Outline the garden's perimeter and dig out the center to create a shallow basin, typically 6 to 12 inches deep. Gently slope the sides to create a bowl shape and set aside the topsoil for use in other parts of your landscape.
Step 4: Soil Amendment
If your soil is heavy clay—common in many Lane County neighborhoods—mix in a combination of compost and coarse sand. This improves the infiltration rate and ensures that water moves through the soil rather than pooling indefinitely.
Step 5: Directing Water Flow
Redirect your downspouts or surface runoff toward the garden using a rock splash pad or a gentle swale. This prevents erosion at the entry point and ensures the water enters the basin evenly.
Step 6: Selecting Native Plants
Choose native species that can handle both saturated soil and periods of drought. Recommended plants for the Willamette Valley include Red-osier Dogwood, Slough Tera, and various native sedges or rushes.
Step 7: Planting and Mulching
Install plants according to their moisture preference, placing the most water-tolerant species in the center. Apply a 2-to-3 inch layer of shredded hardwood mulch to suppress weeds and keep the soil moist.
Expert Tips
- Avoid using river rocks as mulch, as they can float away during heavy Oregon winter rains.
- Plant in clusters of three to five to create a more natural look and better ecological support for local pollinators.
- Monitor the garden for the first two seasons to remove invasive weeds before the native plants fully establish.