A Guide to Rain Gardens to Improve Urban Air Quality
If you’re reading this blog, you’ll be aware that I’ve previously explored the many benefits of rain gardens, how they can help manage stormwater runoff, keep plants hydrated and make outdoor spaces look beautiful.
Another advantage of rain gardens is that they can improve urban air quality by reducing the amount of pollutants that enter waterways. The use of native plants in rain gardens can improve urban air quality – and trees in rain gardens act as natural air purifiers by absorbing carbon dioxide and releasing oxygen.
As well as this, rain gardens help mitigate the production of ozone and smog, leading to improved air quality and a reduction in respiratory issues among urban residents.
In this article I’m going to further examine the role of rain gardens to improve urban air quality, as well as how to best design and implement an urban rain garden.
After all, many people remain unaware of the full benefits of rain gardens, how they function and how they keep our air clean.
Ready to learn more about the role of rain gardens to improve urban air quality? Keep reading…
Rain Gardens to Improve Urban Air Quality: Table of Contents
The Role of Rain Gardens to Improve Urban Air Quality
Let’s start by examining the main ways urban rain gardens improve air quality within densely populated urban areas:
1. Filtering Pollutants
Rain gardens serve as natural filters, capturing and purifying rainwater runoff from impervious surfaces like roads and sidewalks.
As this water percolates through the soil and plant roots, it undergoes a process known as phytoremediation, during which harmful pollutants and contaminants are removed or broken down.
This helps prevent these pollutants from entering stormwater systems and ultimately reaching local water bodies, reducing the risk of water pollution and improving overall environmental health.
Cleaner stormwater also contributes to fresher air quality by lowering the release of airborne contaminants into the atmosphere.
2. Growth of Native Plants
You may think that the type of plants you grow in your rain garden don’t have much of an effect on the air.
Wrong!
If you choose native plants and trees for your garden, they can act as natural air purifiers.
Native plants are those that are adapted to local climate and soil conditions, so your rain garden plant choice will depend on what country you live in.
Through photosynthesis, they absorb carbon dioxide and release oxygen, mitigating the concentration of greenhouse gases in the atmosphere and increasing oxygen levels.
Your rain garden plants also trap airborne particulate matter and pollutants on their surfaces, preventing them from being inhaled by people living in the surrounding area.
3. The Cooling Effect
Did you know that the cooling effect of urban rain gardens contributes to better air quality?
As these green spaces provide shade and lower ambient temperatures, they reduce the formation of ground-level ozone and smog.
High temperatures can trigger the chemical reactions that lead to the creation of these harmful pollutants.
What Rain Garden Plants Work Best to Improve Air Quality?
As discussed above, creating an effective rain garden for air purification involves selecting native plants that can thrive in your local climate and soil conditions.
Here’s a list of some of the best plants to consider for purifying the air in rain gardens (please note: the plants you choose will depend very much on the region you live in!)
- Swamp milkweed (asclepias incarnata): this native perennial attracts pollinators and helps filter pollutants from the water.
- Joe-Pye weed (eutrochium purpureum): with its tall stems and pink-purple blooms, Joe-Pye weed not only looks beautiful but also attracts butterflies while filtering water.
- Switchgrass (panicum virgatum): this grass is drought-tolerant and can help stabilise soil while improving water quality.
- Coneflower (echinacea purpurea): known for its striking purple blooms, coneflower attracts pollinators and helps filter contaminants from rainwater runoff.
- Blue flag iris (iris versicolor): a wetland plant that can thrive in rain gardens, it provides excellent water filtration and habitat for wildlife.
- Buttonbush (cephalanthus occidentalis): this shrub produces unique spherical blooms and is excellent at filtering water.
- Bee balm (monarda spp.): aromatic and attractive to pollinators, bee balm also helps remove pollutants from rainwater.
- Lobelia (lobelia cardinalis): a wetland plant that thrives in rain gardens and helps filter water while providing colour.
- Sedge grasses (carex spp.): these grasses can tolerate wet conditions and assist in soil stabilisation and water purification.
- Sweet flag (acorus calamus): a versatile plant that thrives in both wet and dry conditions, helping improve water quality.
- Black-eyed Susan (rudbeckia hirta): known for its cheerful yellow blooms, it attracts pollinators and assists in filtering runoff.
- Horsetail (equisetum spp.): an ancient plant that can thrive in wet environments and improve water quality.
You may also want to consult with a local nursery or landscape expert who can help you choose the most suitable native plants for your rain garden to maximise its air-purifying and water-filtering capabilities.
Other Benefits of Urban Rain Gardens
There are other important benefits of urban rain gardens to consider along with their ability to improve urban air quality. Two of the most notable include:
1, Filtering Stormwater
As you’re likely aware, rain gardens are designed to capture and filter stormwater runoff from impervious surfaces such as roads, sidewalks, and buildings.
The filtered water is then infiltrated into the ground, which helps to recharge the groundwater table and keep your plants hydrated and fresh!
2. Promoting Biodiversity
Rain gardens can also help promote biodiversity in urban areas by providing natural habitats for a range of plant and animal species.
This can help to support local ecosystems and improve the overall health of the environment.
Rain Gardens to Improve Urban Air Quality: Maintenance
Rain gardens are easy on the eye and have many practical uses, but naturally they require maintenance to sustain their benefits.
If you want to ensure that your rain garden continues to function effectively, you’ll need to follow some basic maintenance practices.
1. Sustaining Biodiversity
To maintain biodiversity in your rain garden, you need to ensure that the plants are healthy and well-maintained.
This means removing any dead or diseased plants and replacing them with new ones.
You should also avoid using pesticides or other chemicals that could harm the plants or the wildlife that depends on them.
2. Long-Term Maintenance
To ensure the long-term sustainability of your rain garden, you’ll need to plan for its maintenance over the years.
For example, drought is a common problem in many areas, and it can be especially challenging for rain gardens.
To avoid drought-related problems, you should choose drought-tolerant plants, that can withstand periods of dry weather.
You could also consider installing a rain barrel or other water storage system to collect rainwater for use during dry periods.
Rain Gardens to Improve Urban Air Quality: Final Thoughts
Many of you reading this will be residents living in urban cities. You may have already designed your garden (or are planning to) and are looking for further information or reassurance.
In this article, you’ve learned how rain gardens are a remarkable solution for improving urban air quality while offering a plethora of other benefits.
By filtering pollutants from stormwater runoff, nurturing vegetation that acts as natural air purifiers, and providing a cooling effect in urban areas, rain gardens play a vital role in creating healthier and more sustainable cities.
But, remember that choosing the right mix of native plants and maintaining your rain garden is crucial for its long-term effectiveness in enhancing air quality and supporting local ecosystems.
As urbanisation continues to grow, embracing rain gardens as a sustainable solution is a win-win for both the environment and the well-being of urban residents.
So, if there are any community organisers or city planners reading this, you may be inspired to make your case on the positive impact a rain garden can have on urban air quality and the broader ecosystem!
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