Rain Gardens – FAQ – Frequently Asked Questions

: What is a rain garden? 

A: A rain garden is a shallow, constructed depression that is planted with deep-rooted native plants & grasses. It is located in your landscape to receive runoff from hard surfaces such as a roof, a sidewalk, and a driveway. Rain gardens slow down the rush of water from these hard surfaces, holds the water for a short period of time and allows it to naturally infiltrate into the ground. more

Q: Why rain gardens are smart and easy to install?

A: Basically, rain gardens are an inexpensive, simple to implement, and environmentally sound solution to urban stormwater runoff. more

Q: What is NPS pollution? 

A: Our activities and development on land alters how water naturally travels through the landscape or watershed. As we develop the land, we add roads, houses, parking lots, sidewalks, and driveways. These hard surfaces are called impervious surfaces because water can not pass through them as it does through soil so the water is forced to evaporate or run off. 

Q: How long does water stay in a rain garden?

A: If designed and installed correctly a rain garden should not hold water for longer than 24 hours. Be sure to test the infiltration rate (see building a rain garden) before planting and adding mulch.

Q: Are rain gardens breeding areas for mosquitoes?

A: No. For reproduction, mosquitoes require 10-14 days of standing water. There is rarely standing water long enough in a well-designed rain garden to allow mosquitoes to reproduce.

Q: What happens to the plants when we have a dry period?

A: Native plants can live and thrive in a range of weather conditions. Those that are used to having their “toes” wet are placed in the lowest part of the garden and can withstand wet and some dry periods. Those that like dryer soil are placed on the banks of the garden and can withstand some wet and very dry conditions.

Q: How large must a rain garden be to work?

A: Any water that seeps into the ground instead of running into a storm sewer or river helps water quality? A rain garden of any size has a positive impact.

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