What depth is the planting medium in a rain garden typically?

The typical depth of the planting medium in a rain garden is generally around 2 feet. This depth is sufficient to support the growth of a variety of native plants while also ensuring effective stormwater management. A 2-foot depth allows for adequate water retention and infiltration, facilitating the absorption of runoff from impervious surfaces, which is one of the primary purposes of a rain garden.

Rain gardens are designed to temporarily hold water during rain events, allowing it to percolate into the soil, while the depth needed needs to balance between not being too shallow (which may result in overflow) and not being too deep (which could create complications with water retention and plant growth). A depth of 2 feet is a practical standard that provides the right environment for the biodiversity aimed at in such eco-friendly landscaping designs, ensuring healthy root systems and effective filtration of pollutants from the water before it reaches the groundwater.