Dry Creek Bed for Drainage
I have a client who lives on a large piece of property with an equally sized drainage problem. My solution is to direct the water off the property with a long dry creek bed. My question is: what are good plants for a dry creek bed? Are they the same as for a rain garden? This is for the Portland-metro area. Thanks in advance!
The answer to your question depends on whether the swale is designed to infiltrate or route water away like a rain garden. Rain gardens have a variety of plants based on where they are located in the garden and how long it takes the water to infiltrate.
We talk about these planting zones in our Oregon Rain Garden Guide. You can purchase this online or download a low resolution copy for free at this website - http://seagrant.oregonstate.edu/sgpubs/oregon-rain-garden. See page 20.
You will place plants that can withstand more water in the bottom of the swale, and plants that are more drought tolerant on the sides and top of the swale. If your swale has standing water for long periods of time, then you will have to use wetland plants in this wet zone. This may be a key difference between your swale and a properly designed rain garden because rain gardens are designed to drain in less than 48 hours. I have seen many swales that hold water for longer periods of time, so you may have to adjust your plant types.
Let me know if you need more advice. Another great source for you is the East Multnomah Soil and Water Conservation District. They have done quite a bit of work with rain gardens in the Portland area.