2025’s Best Cities for Rain Gardens

What are the 3 biggest environmental benefits of rain gardens? 

1. They can infiltrate stormwater and reduce runoff volumes. 
2. They can improve the water quality of stormwater runoff by reducing some (but not all) pollutant loads to downstream water bodies. 
3. They look nice and are relatively simple to install.

How do rain gardens help with stormwater management and pollution reduction? 

They promote infiltration into the existing soils and reduce runoff volumes. The soil of a rain garden can act as a filter that retains solids and pollutants adsorbed to the soil, such as metals and phosphorus. Dissolved metals can also be retained by the soil media and/or be used by plants.

What are the 3 most common challenges or misconceptions about rain gardens? 

1. As with all stormwater management practices, rain gardens require maintenance, which takes time, money, and effort. Maintenance costs can exceed construction costs in as little as 5 years, depending on the size of the rain garden. 
2. In soils that can not infiltrate water quickly enough, underdrains may need to be installed.
   In this case, the rain garden acts like a filter and passes the water downstream instead of having it infiltrate into the existing soil. The problem with this is that the rain garden media contains compost and other organic material that leach dissolved phosphorus and nitrogen into the effluent.
   The result is that the rain garden may contribute to nitrogen and dissolved phosphorus pollution instead of helping to reduce it.
3. Anytime you infiltrate runoff with pollutants, you have to be careful about what you are putting into the ground and where it is going. You shouldn’t infiltrate in certain soils or above sensitive aquifers, such as drinking water aquifers. 
4. Another challenge is public acceptance and general knowledge, as some may not like the looks of a rain garden or want one on their property. Homeowners and maintenance crews also need to know not to mow in a rain garden or remove/replace the plants, which have been carefully selected to survive and function in rain garden conditions to meet certain objectives.

How do rain gardens fit into broader climate resilience or green infrastructure strategies? 

Rain gardens are just one piece –– an important piece –– of effective stormwater management because they can help reduce runoff volumes and pollutant loads. Large rainstorms are becoming more frequent, however, and in this case, the relatively small storage volume of a rain garden typically does little to reduce flooding. In those cases, larger stormwater ponds are more effective.

What are the 3 biggest environmental benefits of rain gardens?

In short, rain gardens provide three primary environmental benefits: 

1. Runoff volume reduction
2. Pollutant capture and removal
3. Aesthetic benefits

How do rain gardens help with stormwater management and pollution reduction?

When properly designed, constructed, and maintained, rain gardens capture stormwater runoff and infiltrate it into the ground, which mimics the natural water cycle that occurred before we created our urban landscapes. Rain gardens also capture numerous pollutants from stormwater runoff, including sediment; nutrients such as nitrogen and phosphorus; metals such as copper, cadmium, lead, zinc, and others; organic chemicals such as polycyclic aromatic hydrocarbons (PAHs); bacteria, and pathogens, among others. 

Rain gardens reduce the amount of excess runoff volume and stormwater pollution that gets to our lakes, rivers, streams, and wetlands. In addition, rain gardens provide aesthetic beauty and benefit to the landscape into which they are installed, which has been shown to increase property values, improve mental and physical health, and provide habitat for pollinators and other ecosystem-beneficial species.

What makes a city ideal for encouraging or implementing rain gardens?

Before modern cities were built, rainfall onto the landscape would mostly infiltrate into the ground. Most cities and urban landscapes are constructed of rooftops, roadways, parking lots, sidewalks, and driveways that are impervious and impenetrable to rain that falls. These surfaces shed water and create stormwater runoff. 

In most cities, stormwater runoff does not go to a treatment plant. Rather, it carries pollutants from the landscape and needs treatment before flowing into our lakes, rivers, streams, and wetlands. A city is an ideal location for implementing rain gardens because they fundamentally represent the natural water cycle of rain infiltrating into the ground. Rain gardens have the added benefit of removing pollutants created by the urban landscape and beautifying our neighborhoods. 

How can homeowners or communities start building rain gardens?

Homeowners and communities can call or email the staff in their cities (usually Public Works) for information on how to start building rain gardens. They can also look for grant programs to help offset the cost of building a rain garden on their property; grants are often provided by the local city, county, or state. 

What are the 3 most common challenges or misconceptions about rain gardens?

1. Myth: Rain gardens are a lot of work.
   Because rain gardens are natural, living micro-ecosystems, they do require some upkeep to continue to function properly. Regular maintenance includes removing weeds, replanting vegetation after extreme weather events, and removing litter and debris that flows in from the streets. Owners can often spend as little as a few hours per year to keep a rain garden looking and functioning great, but others can invest much more if they have a passion for it!
2. Myth: Rain gardens are expensive.
   While the initial cost to create a rain garden from scratch may seem scary, the actual cost is often only a few thousand dollars and can be offset with grant programs. In some communities, there are groups that help homeowners build rain gardens or a community event to build multiple rain gardens. Seek help from your city if you want to implement this near you!
3. Myth: Rain gardens are just for being pretty.
   While rain gardens can be beautiful botanical features in our landscape, they also provide numerous benefits to water quality and water quantity!

How do rain gardens fit into broader climate resilience or green infrastructure strategies?

Rain gardens are among a bigger group of ‘green infrastructure’ practices used to manage stormwater runoff. Green infrastructure uses vegetation and infiltration to minimize stormwater runoff and reduce stormwater pollution, in contrast to grey infrastructure like pipes and concrete channels which only convey water from one place to another. Rain gardens and green infrastructure have been shown to improve climate resilience in urban landscapes by slowing down runoff, infiltrating stormwater, and creating dispersed storage throughout the watershed. 

What are the 3 biggest environmental benefits of rain gardens?

The biggest environmental benefits of rain gardens would be:

1. They can treat stormwater runoff and filter out pollutants like heavy metals and excess nutrients.
2. They can reduce the flashiness of urban hydrology and cut down on flooding.
3. They can provide additional habitats in the built environment for birds and insects to promote biodiversity.

How do rain gardens help with stormwater management and pollution reduction?

Rain gardens help with stormwater management and pollution reduction because they are designed to perform ecological functions like infiltration and promote biogeochemical cycling. Rain garden soils are designed to infiltrate stormwater, slowing the flow of surface runoff and promoting ecological processes that treat that water. Soil particles and microbes can treat and retain pollutants, and plants growing in rain gardens can take up those pollutants, preventing them from reaching ground and surface waters.

What makes a city ideal for encouraging or implementing rain gardens?

Cities can be ideal for encouraging or implementing rain gardens due to both physical and social characteristics. Being in a climate with frequent and intense rainfall can help, but really, the combination of impervious surfaces with precipitation makes any city suitable for using rain gardens. 

For example, rain gardens in more arid cities are important for harvesting stormwater to support plant growth, so they can rely less on potable water for landscaping. Cities with holistic planning approaches that integrate rain gardens with other stormwater management practices and with related environmental issues, such as biodiversity and carbon management, can see success in implementation. Also, places that consider inequities in green spaces and environmental justice aspects of urban ecological planning will also help encourage practice. 

Often, policies that are supportive of rain gardens contribute to implementation as well. For example, a combination of mandates with active and engaged education programs and financial support (i.e., rebates for design and implementation of rain gardens) can help overcome barriers to practice.

How can homeowners or communities start building rain gardens?

Considering site features and natural flow paths of surface waters is a great place to start. Observe how water already flows through or near properties and identify points where water might be collecting. Soil assessment can tell you if you need to amend soils or add certain texture classes to promote infiltration or support plant growth. It is a good idea to check your local municipalities and cooperative extension for programs to help with design, planning, and paying for rain gardens. Collaborating with neighbors can be a great way to host digging/planting parties, or even apply for local grants to support implementation.

What are the 3 most common challenges or misconceptions about rain gardens?

A big misconception is that rain gardens are a habitat for mosquitoes. If designed properly, water will drain out quickly enough that mosquito larvae will not be a problem. The need for maintenance is a challenge to rain gardens functioning properly over time, and that’s something that is often overlooked. They may accumulate trash; plants may die out or need to be maintained or replaced (and you may even get volunteer plants that need to be weeded out) over time. 

Another misconception is that a rain garden will not have much impact, but even a single residential rain garden plays an important role in our urban ecology. Designed and implemented in your landscape, a rain garden can have a big impact on runoff, flooding, and diversity. Also, a single rain garden can be a great conversation point to spread the practice throughout neighborhoods. At scale, the functions each garden provides compound, and with integrated design practices, the benefits to stormwater management and biodiversity can have a significant additive effect.

How do rain gardens fit into broader climate resilience or green infrastructure strategies?

Rain gardens are an important part of climate resilience strategies, especially when you think about resilience as a way to adapt to climate change. Many cities will experience increases in precipitation; rain gardens can help reduce the potential runoff generated by this change in storm intensity and frequency. 

In places where climate change may bring drought or longer periods between rainfall, rain gardens can harvest water to help support plants during those drier spells. Rain gardens should be thought of as a part of broader green infrastructure and stormwater management strategies. 

Rain gardens may be appropriate as retrofits to reduce impervious cover in already developed neighborhoods in ways that larger BMPs may not fit. They may also be better suited for residential spaces due to the additional benefits to habitat, diversity, and aesthetics that they can provide.

What are the 3 biggest environmental benefits of rain gardens?

• Reduce runoff and flooding: Rain gardens capture and slow stormwater, reducing localized flooding, erosion, and pressure on drainage infrastructure.
• Improve water quality: Rain gardens filter out pollutants such as nutrients, sediments, and hydrocarbons before they reach nearby rivers, lakes, or bays.

• Support urban biodiversity: Rain gardens provide habitat for native plants and pollinators, enhancing ecological health in developed areas.

How do rain gardens help with stormwater management and pollution reduction?

• Naturally manage runoff: Rain gardens collect and infiltrate rainwater from rooftops, driveways, and streets, reducing peak flow and runoff volume.
• Improve water quality: Pollutants are filtered through vegetation and soil layers, where contaminants like nutrients, heavy metals, and oils can break down or be retained.
• Reduce sewer overflows: In combined sewer areas, rain gardens reduce the volume of stormwater entering sewers, helping to prevent overflows during large storms.

What makes a city ideal for encouraging or implementing rain gardens?

• High impervious cover: Urban areas with lots of pavement benefit from capturing runoff at the source.
• Aging stormwater infrastructure: Cities with overburdened or outdated systems can adopt rain gardens as cost-effective retrofits to mitigate flooding and reduce infrastructure strain.
• Supportive policies and incentives: Municipalities that provide guidance, promote community awareness and education, and offer credits, rebates, or regulatory requirements for on-site stormwater control help facilitate broader adoption of rain gardens.

How can homeowners or communities start building rain gardens?

• Choose a suitable location. Select a low-lying site, at least 10 feet away from building foundations, utilities, and tree trunks, where water naturally flows or can be directed.
• Test the soil. Conduct a simple do-it-yourself (DIY) infiltration (percolation) test to ensure the soil drains at least a quarter inch per hour. To perform the test, clear vegetation from the area, dig a small hole (typically 6 to 8 inches deep), fill it with water, and measure how long it takes to drain completely.
• Determine size and shape. A common guideline is to size the rain garden to be roughly 10% of the impervious drainage area (e.g., 200 sq. ft. for a 2,000 sq. ft. roof).
• Excavate and plant. Dig a shallow basin with a total depth of approximately 18 to 36 inches. Backfill with 12 to 24 inches of amended soil mix, leaving a surface depression of 6 to 12 inches to temporarily hold stormwater. The amended soil should typically consist of 50% sand, 25% topsoil (with low clay content), and 25% compost by volume, to ensure good drainage and plant health. Select hardy native plants that tolerate both wet and dry conditions (e.g., blue flag iris, swamp milkweed, Joe-Pye weed, sedges, etc., in many regions)​. Apply mulch to help retain moisture, suppress weeds, and prevent surface erosion.

• Redirect water. Use swales, downspout extensions, or curb cuts to direct runoff into the rain garden, and include a stabilized overflow path for larger storm events. Ensure the garden is located where any overflow will not flood nearby structures or hardscape areas. This precaution reinforces best practices by allowing excess water to safely spill to a drain, swale, or lawn area once the ponding zone reaches capacity during extreme storms.
• Plan for drainage in tight soils. If soil infiltration is slow (less than a quarter inch per hour) or the rain garden has a depression depth greater than 12 inches, consider installing a surface orifice outlet or a subsurface perforated pipe underdrain at the bottom of the garden. This design feature helps prevent prolonged ponding and ensures reliable drainage. For detailed guidance, see the ASCE-published study.
• Follow local rules and design standards. If rain gardens are intended to meet local stormwater management requirements or other regulatory frameworks, consult qualified local professionals and refer to relevant programs and design manuals.

What are the 3 most common challenges or misconceptions about rain gardens?

1. “They attract mosquitoes.” Not if designed properly; rain gardens are intended to drain within 24–48 hours, which is too quickly for mosquito breeding cycles.
2. “They require too much maintenance.” After establishment, rain gardens require only light upkeep, such as occasional weeding, replanting, periodic mulching, and clearing of inlets and outlets—comparable to any standard garden bed.
3. “They’re too expensive or difficult.” Many effective rain gardens can be installed by homeowners for a few hundred dollars without professional help.

How do rain gardens fit into broader climate resilience or green infrastructure strategies?

• Sustainable stormwater management: Rain gardens (also known as bioretention cells) reduce stormwater runoff volume, improve water quality by filtering pollutants, enhance groundwater recharge, mitigate street and basement flooding, and help protect stream banks from erosion. They also help during drought by allowing water to soak into the ground.
• Nature-based infrastructure: They serve as green infrastructure that supplements or reduces reliance on traditional gray systems like pipes, storm sewers, and pump stations, particularly in small to moderate storms. As vegetated systems, they also sequester small amounts of carbon in plant biomass and soils.
• Climate adaptation and urban resilience: Rain gardens help cities manage increasingly frequent and intense storms, reduce urban heat through water evaporation and evapotranspiration from vegetation, and enhance neighborhood livability and ecological health.