LEARN MORE ABOUT
Downspout Planters
Does the water from your downspouts currently discharge directly onto a driveway or street, or into an underground pipe leading to a storm sewer? If you’re interested in helping our environment by capturing stormwater but lack the space for features like rain gardens, a downspout planter could be the perfect solution for you!
What is a downspout planter?
Downspout planters, a.k.a. “flow-through planters”, are decorative planted containers designed to filter and retain storm-water from roof gutters. These planters are like a combination of a rain barrel and a rain garden; native plants and soil in the top section help filter & absorb stormwater, and vacant space in the bottom section captures & stores it.
Since 2020, our Streamsmart House Calls program has constructed and distributed over 45 downspout planters within the Darby Cobbs Watershed. Using plans from the Philadelphia Water Department, we construct them using 100 gallon galvanized stock tanks.
How do they work?
Galvanized Stock Tank Planters
This type of downspout planter has two main sections: a top and a bottom. The top section is filled with soil which is optimal for infiltrating rainwater and native perennial plants. This area is supported by a false-bottom made of perforated PVC, underneath which is a vacant chamber that stores stormwater.
When it rains, water from your downspout flows into the planter, passing over round stones placed to slow the water down. This water begins to pool, slowly infiltrating into the soil where it is used by native plants. Some of this water passes through the false bottom and into the bottom storage chamber where it collects. At the bottom of the planter is a valve which releases the stored water slowly, allowing it time to evaporate rather than flow into local storm drains.
Credit: Rain Check - Philadelphia Water Department
Wooden Downspout Planters
As opposed to having two different sections, these planters are filled completely with natural materials and designed with a focus on absorbing and filtering the rain water rather than evaporating it. The bottom of the planters are filled with layers of gravel and sand topped with soil that supports native plants.
Water from a downspout is channeled into the planter, filtering down through the various layers until it reaches an outflow pipe. This outflow pipe drains either to an existing standpipe or onto an adjacent surface. While these are more time-consuming to construct, they do offer a beautiful aesthetic appearance.
How can I build my own downspout planter?
Depending on the amount of time, money, and tools you have access to, you can construct a planter that suits your aesthetic preferences and site conditions. If you’d like a quicker build and rustic look, consider building your planter using a hundred gallon galvanized stock tank. These tanks can be acquired from local home improvement stores or retailers like Tractor Supply, Lowes or Home Depot. You can find a design guide from the Philadelphia Water Department.
If you have time and want something that looks a bit nicer, consider building a wooden downspout planter. For information on building wooden downspout planters, please visit pages 94-99 of the Rutgers Green Stormwater Infrastructure Guide.
Planting and Maintenance
Plants used in rain gardens typically do well in downspout planters. As with any garden, you’ll want to take into consideration the sun requirements of any plants you choose and keep them watered and weed-free for the first couple months until they become established. For information on maintenance and troubleshooting, please visit our Downspout Planter Maintenance Guide!
For a list of optimal plant species, please visit Penn State Extension - Rain Gardens: The Plants. If you’re curious about where to acquire native plants for your planter, please visit our native plants webpage for a list of retail nurseries.
Don’t have the resources to build one for yourself?
If you live in our service area, you may be eligible for a discounted installation through the Stream Smart Stormwater House Calls program. To schedule a housecall for your home, please visit https://streamsmarthousecalls.org/.