Spring 2011 1 

Introduction

Communities throughout the country are turning to urban agriculture and 

gardening as a reasonable option to increase their access to healthy, nutritious, and 

low-cost produce. Some of the sites that communities are using for urban gardens 

were previously home to industrial and commercial operations. A garden on 

abandoned land can become a new community asset by improving the visual look 

of a neighborhood and potentially increasing nearby property values. Community 

gardens provide many benefits, including healthier lifestyles by increasing activity 

levels, providing fresh produce, growing community pride, and nurturing social 

interactions and cooperation among people.

For communities interested in gardening on a site that might be contaminated, it is 

important to first determine the health and suitability of the soil at the site. It is a 

common gardening practice to test soil for characteristics such as pH and nutrient 

availability. When creating a garden on land with an industrial or commercial 

history, it is highly recommended that communities consider the site’s land use 

history and test the soil accordingly for potential contamination. Knowledge of soil 

health and potential contamination are keys to helping communities identify and 

correct problems so that each urban garden is safe and productive. 

The possibility of contamination at a garden site should not keep you from planning 

an urban garden there. This fact sheet presents steps that you can take to find out 

and address potential contamination at your site to help create a safe and healthy 

garden for your community. 

U.S. Environmental Protection Agency

Office of Superfund Remediation and Technology Innovation

This fact sheet provides communities and individuals with general 

urban gardening information about:

• Common contaminants that can be found in urban soil. 

• Ways to identify contaminants and reduce exposure. 

• Improving soils and growing plants in mildly contaminated soil.

• Additional resources and technical assistance.

More information for the urban 

gardener on soil science, soil 

amendments, plants, contaminants 

and their health effects, and 

additional links is available on EPA’s 

CLU-IN website: www.clu-in.org/

ecotools/urbangardens.cfm.

REUSING POTENTIALLY CONTAMINATED LANDSCAPES:

Growing Gardens in Urban Soils

 EPA/542/F-10/011
2 Urban Gardening

Soil Qualit y

Q: Why Is Healthy Soil Important for Your Garden? 

A: Healthy soil is essential for plants to grow in your garden. When a 

property has been used for industrial or commercial activities, the 

soil is often nutrient deficient, highly compacted and potentially 

contaminated. These soils can be improved and made healthy again 

so that your garden plants can grow and thrive. Healthy soil holds 

water and contains beneficial organisms, plant nutrients, and organic 

matter. 

Soil Nutrients

Soil nutrients are vital for healthy soil and must be available for plants to grow. 

Soil tests will help you determine the existing nutrients available in your soil and 

indicate which nutrients and nutrient amounts need to be added. Mineral nutrients 

such as nitrogen, phosphorus, potassium (NPK), and calcium can occur naturally 

in the soil, but often need to be applied to maintain a healthy balance. Soil nutrients 

may be added in various forms, including: fertilizer and lime (available in most 

gardening stores) and organic matter such as grass clippings, leaves, and compost. 

Physical Properties of Soil

The physical properties of soil determine how well nutrients are available to plants. 

Soil contains a combination of sand, rock, silt, clay, air, and organic matter, which 

affects its ability to hold nutrients and water. 

You can improve the physical quality of your soil by leveling and loosening the 

soil and adding organic matter such as compost and manure. These additions can 

increase the amount of water that sandy soils can absorb or hold and can improve 

the drainage of clay soils. 

Soil pH

Soil pH affects the amounts and types of nutrients available to plants through their 

roots. The pH scale goes from 0 to 14; a pH of 7 is neutral. A lower number means 

a more acidic soil, while a higher number means a more basic or alkaline soil. 

Certain nutrients are less available to plants in soils 

where the pH is too low or too high. When a soil’s pH 

is near neutral, nutrients are more readily available to 

plants, and microbial populations in the soil increase. 

A soil test will tell you the pH of your soil. Based on 

this information, you will be able to determine whether 

soil amendments (soil additions) are needed to change 

the pH of your soil to meet your gardening needs. You 

can raise the pH of soil by adding lime or wood ash. 

You can lower the pH of soil to make it more acidic 

by using fertilizers containing ammonium-nitrate or 

specialty fertilizers for “acid-loving” plants that contain 

ammonium sulfate or sulfur-coated urea.

For more information on amendments that can be used 

to improve soil quality, see Techniques for Addressing 

Soil Contamination in the Resources section in this fact 

sheet, page 11. 

acidic

neutral

basic

pH Scale

2 Urban Gardening
Spring 2011 3 

What 

Are Soil 

Background 

Levels?

Background levels are 

the naturally occurring 

levels of elements and 

chemicals found in any 

soil. Background levels 

differ depending on the 

region of the country in 

which you live. In some 

areas background levels 

for certain elements and 

chemicals may be higher. 

Contact your local 

extension service or state 

environmental agency 

(see Technical Assistance 

in the Resources section, 

page 10) for help in 

learning more about 

elemental background 

levels for the soil in your 

neighborhood. 

More information on 

soil background levels 

in the United States is 

available at: http://pubs.

usgs.gov/of/2005/1253/

pdf/OFR1253.pdf.

Spring 2011 3 

Contaminants

A soil contaminant is an element or chemical present in the soil at a level that could possibly 

pose health risks. In a few areas of the country, element levels may be naturally high. In many 

cases, human activities have increased the soil levels of many elements and chemicals and 

also spread them out more widely. Lead, cadmium, arsenic, zinc, and polycyclic aromatic 

hydrocarbons (PAHs) are contaminants commonly found in any urban environment. In 

addition, other contaminants can also be found in areas near former commercial or industrial 

properties. Table 1 lists sources of contamination that are commonly found on sites with a 

commercial or industrial history.

Table 1. Common Sources of Contamination1

1	 Adapted from Heinegg, A., Maragos, P., Mason, E., Rabinowicz, J., Straccini, G. and Walsh, H. (2000) Urban Agriculture and Soil

Contamination, available at: http://cepm.louisville.edu/Pubs_WPapers/practiceguides/PG25.pdf.

General Source Examples of Previous Site Uses Specific Contaminants

Paint (before 1978)

Old residential buildings; mining; leather

tanning; landfill operations; aircraft component manufacturingLead

High traffic areas

Next to heavily trafficked roadways or

highways; near roadways built before

leaded fuel was phased out

Lead, zinc, polycyclic aromatic hydrocarbons (PAHs)

Treated lumber Lumber treatment facilities Arsenic, chromium, copper

Burning wastes Landfill operations PAHs, dioxins

Contaminated manure Copper and zinc salts added to animal

feed Copper, zinc

Coal ash Coal-fired power plants; landfills Molybdenum, sulfur

Sewage sludge Sewage treatment plants; agriculture Cadmium, copper, zinc, lead, persistent

bioaccumulative toxins (PBTs)

Petroleum spills

Gas stations; residential/commercial/industrial uses (anywhere an aboveground

or underground storage tank is or has

been located)

PAHs, benzene, toluene, xylene, ethyl

benzene

Pesticides

Widespread pesticide use, such as in

orchards; pesticide formulation, packaging and shipping

Lead, arsenic, mercury, chlordane and other

chlorinated pesticides

Commercial/industrial site use

PAHs, petroleum products, solvents, lead,

other heavy metals (such as arsenic, cadmium, chromium, lead, mercury and zinc)

Dry cleaners Stoddard solvent and tetrachloroethene

Metal finishing operations Metals and cyanides

EPA’s Toxic Release Inventory (TRI) can provide information to communities about sites where contaminants were 

released into the environment. The Envirofacts database allows users to enter location information, such as zip code, 

address or county location, to get information about releases in their area. The database is available online at: www.

epa.gov/enviro.
4 Urban Gardening

Biosolids

Biosolids are the nutrient-rich organic materials resulting from 

the treatment of sewage sludge (the name for the solid, semisolid or liquid untreated residue generated during the treatment 

of domestic sewage in a treatment facility). When treated 

and processed, sewage sludge becomes biosolids, which are 

tested for safety to be recycled and applied as fertilizer to 

improve and maintain productive soils and stimulate plant 

growth. Only biosolids that meet the strictest state and 

federal standards can be approved for use as a fertilizer. 

More information on how biosolids have been used to solve 

problems on potentially contaminated lands is available at: 

www.cluin.org/ecotools/soil.cfm.

More information on biosolids is available at: http://water.

epa.gov/polwaste/wastewater/treatment/biosolids/genqa.

cfm. 

Contaminants continued

Q: How Do I Know if My Property is Contaminated?

A: You can conduct a formal environmental assessment (study) of the land you are 

interested in using for urban gardening. There are two types of assessments: 

Phase I and Phase II Environmental Assessments. A Phase I assessment 

includes a review by a trained environmental professional of historical site 

uses, interviews with neighbors and, if possible, site owners, and a visual site 

inspection to determine the potential for and type of contamination at a site. If 

a Phase I assessment determines that there is potential for contamination at the 

site, a Phase II assessment is conducted to sample for contaminants and locate 

any impacted areas. 

For more information on Phase 1 and Phase 2 assessments, contact your local 

and state environmental agencies. Some local governments may even be able to 

provide you with a Phase I or Phase II environmental assessment or have qualified 

environmental professionals on staff who can conduct the assessment.

Q: What if My Community Needs Help with Site Assessments, Sampling or 

Cleanup?

A: Federal funding is available to government entities to conduct 

brownfields (property where reuse may be complicated due to on-site 

contamination) assessments. Working with local officials to apply for 

an EPA brownfields grant can provide money for your community 

to assess or clean up the property you are interested in as well as 

address other properties.

What you need to know to get started in applying for brownfields 

grants can be found at: www.epa.gov/brownfields/grant_info/assess/

assessment_factsheet.pdf. 

4 Urban Gardening More information for the urban gardener on soil science, 

effects, and additional links is available on EPA’s CLU-IN 
Spring 2011 5 

What Are EPA Soil Screening Levels (SSLs) and Can 

SSLs Be Used as Limits for Urban Gardening? 

EPA’s SSLs were developed to determine if the soil at Superfund (program that allows 

EPA to clean up hazardous waste sites) sites warrants further study, investigation or 

possibly cleanup depending on how a site is being used (for example, for residential 

or commercial purposes). These screening levels look at several soil-to-human

exposure pathways, including: direct ingestion, dermal exposure, and inhalation. 

EPA’s general guidance states that if an SSL is not exceeded for a pathway of 

concern, the user may eliminate that pathway from further investigation. While EPA 

does not have SSLs for gardening, some states may decide that residential SSLs are 

appropriate to use for gardening purposes, or they may establish appropriate levels 

specific to each site. 

Exposure Pathways

Q: How Could I Come into Contact with Contaminants while 

 Gardening?

A: An exposure pathway is the way that a contaminant comes into 

contact with people. If a site assessment concludes that contaminants 

are present, the next step is to think about potential contaminant 

impacts as you work the soil to garden or eat the food you grow. 

There are two human exposure pathways to soil contaminants: the 

soil-to-human pathway and the soil-to-plant-to-human pathway.

Soil - to -Human Exposure Pathway

While gardening, the greatest risk of exposure to contaminants is from contaminated 

soil getting into your mouth or by breathing in contaminated dust. For example, 

children playing in the garden may directly eat soil through hand-to-mouth play, or 

people may eat plants without first washing them to remove soil and dust. Skin contact 

(dermal exposure) with soils containing contaminants such as PAHs, chromium and 

trichloroethylene (TCE) can pose health risks.

Soil - to -Plan t - to -Human Exposure Pathway

Some edible plants do take up and accumulate contaminants. A plant’s uptake of 

contaminants depends on many factors, including the type of plant and the pH and 

organic content of the soil. However, research shows that there is minimal risk of 

exposure from eating plants grown in contaminated soils. To reduce concerns of 

exposure from eating plants, wash produce thoroughly before eating to remove 

potential soil contamination. Root vegetables have a higher potential for accumulating 

contaminants. In some cases, it may be prudent to avoid growing edible plants in soils 

with high contaminant concentrations. 

Spring 2011 5 soil amendments, plants, contaminants and their health 

website: www.clu-in.org/ecotools/urbangardens.cfm.
6 Urban Gardening 6 Urban Gardening

Wise Urban Gardening

In general, the benefits of urban gardening greatly outweigh the risks. By following 

the recommendations and best practices listed below, you will decrease your 

likelihood of exposure to contaminants that are commonly found in urban soils 

located on sites with past industrial and commercial uses.

Q: What Can I Do to Lower the Chances of Coming into Contact with 

Contaminants that May Be in Present in my Soil?

A: If you find that the soil in which you want to garden is contaminated, 

you may want to first consult with your state and local environmental 

agencies and EPA’s Technical Assistance to Brownfields (TAB) 

program (see Technical Assistance in the Resources section, page 

10) to learn about how to find professional site cleanup specialists 

who can recommend the best techniques for reducing high levels 

of contaminants. The following techniques are commonly used to 

eliminate exposure to soil contaminants: 

• Build raised beds. 

• Use soil amendments to stabilize contaminants in soil. Adding a 

thick layer of organic matter to your soil provides a physical barrier 

to contamination. Soil amendments have also been used to bind 

contaminants so that they are no longer mobile or bioavailable. Soil 

amendments improve the overall soil quality for growing plants and 

are a good addition to any soil.

• Remove all contaminated soil and replace it with clean soil. Make 

sure the replacement soil is clean by asking the supplier for proof 

that the soil that was tested to be contaminant-free.

• Use phytotechnologies, which utilize plants to extract, degrade, 

contain or immobilize contaminants in soil. However, using 

phytotechnologies to clean up contaminants can take many years, 

is not effective for every contaminant, and generally requires special 

handling for the disposal of plants used. Information on specific 

contaminants that can be remediated using phytotechnologies is 

available at: www.cluin.org/download/remed/phytotechnologiesfactsheet.pdf.

More information for the urban gardener on soil science, 

effects, and additional links is available on EPA’s CLU-IN
Spring 2011 7 

Bioavailability 

The risks associated with 

contaminant levels in soil may 

also be much lower than expected 

based on test results because of the 

bioavailability of the contaminant 

in the soil. Bioavailability of a 

contaminant is the amount of 

contaminant that can be taken up 

by your body. It depends on the 

characteristics of the site and the 

soil. For example, for soils rich in 

lead, treatment with phosphate and 

compost has been shown to reduce 

the bioavailability of soil lead, 

decreasing the risk of exposure to 

people . 

P h y t o t e c h n o l o g i e s 

and Lead

Q: Lead is a common contaminant 

in urban soils. Can I use 

phytoremediation to remove lead 

from the soil at my site? 

A: No. Phytoremediation of lead 

in soils is ineffective since lead is 

generally not available for plant 

uptake. However, the use of soil 

amendments is an effective way to 

reduce potential exposure.

Build Raised Beds and Container Gardening 

Building raised beds and growing plants in containers is the most common 

way to reduce the chances of coming into contact with contaminants in urban 

gardens. These gardening techniques are preferred because the clean soil and 

organic matter used to build the raised beds creates a physical barrier between the 

gardeners/plants and possible contamination in the ground soils. Raised beds can 

be built for permanent or seasonal use.

How to build raised beds:

• Place a layer of landscape fabric on top of the ground soil before adding 

the clean soil and organic matter. The fabric layer creates a barrier 

beneath the soil in the bed that prevents plant roots from entering the 

ground soil below the bed.

• Build a frame to hold the clean soil for a permanent raised bed. Ask for 

non-treated lumber when getting wood to build the frame. 

See the National Gardening Association’s how-to video on “Making a Raised Bed 

Garden,” available at: www.garden.org/howtovideos/index.php?page=video2. 

Even when you are using raised bed and container gardens to address contamination, 

airborne contaminants, soil dust, or soil splashback from other areas may still 

enter the raised beds. Consider covering walkways and other areas of exposed 

soil with mulch, grass, or other groundcover to help reduce dust migration and 

splashback onto crops and protect against human exposure when gardening.

Spring 2011 7 soil amendments, plants, contaminants and their health 

 website: www.clu-in.org/ecotools/urbangardens.cfm.
8 Urban Gardening

Best Practices in the Garden

Building raised beds and mulching pathways is an excellent way to reduce the chance of coming into contact with potential 

contaminants. The recommendations below can add another layer of protection if you have raised beds or decide to do inground planting. 

•	 Locate gardens away from old painted buildings and roads with heavy traffic.

•	 Use a thick layer of organic material such as compost or mulch. Place landscape fabric between ground soil and 

new, clean soil.

•	 Watch over small children to stop them from eating soil through hand-to-mouth play.

•	 Wash hands immediately after gardening and before eating to avoid accidentally eating soil. 

•	 Wear gloves as a barrier between your hands and the soil. 

•	 Throw away the outer leaves of greens, especially from the bottom of plants, before washing. Soil particles 

are most likely to be located on the outer leaves of leafy plants.

•	 Wash produce using running water.

•	 Avoid bringing contaminated soil into the home by:

• Cleaning tools, gloves and shoes before bringing them indoors. 

• Putting highly soiled clothes in a bag before bringing them indoors and washing them promptly in a 

separate load. 

• Washing off excess dirt from crops, especially root crops and leafy vegetables, before bringing them 

indoors.

•	 Peel vegetables, especially root vegetables, which are in direct contact with soil.

8 Urban Gardening More information for the urban gardener on soil science, 

effects, and additional links is available on EPA’s CLU-IN 
Spring 2011 9 

Choosing Crops

In general, plants that produce fruiting bodies (for example, tomatoes, squash, apple and pear trees, and berries) are most 

appropriate for growing in potentially contaminated soil. Root and tuber crops (for example, carrots, potatoes and onions) 

are often the least appropriate plants to grow in potentially contaminated soil, as the edible portions of the crops are in 

direct contact with the soil. Vegetables with large outer leaves (for example, cabbage, lettuce and collard greens) are easily 

contaminated by dust and soil splashback, so careful washing of these plants is necessary. 

Conclusion

There are many effective ways to reduce or eliminate any risk from gardening on potentially contaminated land. Gardening 

provides many benefits to communities and individuals. The information in this fact sheet is designed to help you understand 

the steps that your community can take to create healthy garden conditions for growing a variety of delicious and nutritious 

crops. So go dig, plant, harvest and enjoy!

Spring 2011 9 

Steps You Can Take to Reduce Potential Risk from Contaminants When Growing Vegetables:

• Add high rates of compost and other organic soil amendments to the soil (up to 50:50 by volume) in order to 

dilute soil contaminant concentrations, improve the physical properties of soil and plant growth, and make 

contaminants less available for plants to take up.

• Garden in raised beds or containers to separate the garden from the contaminated soil.

To learn about safe levels of soil contamination and the cleanup requirements of sites used for gardening or 

farming in your area, contact your state environmental agency or cooperative extension services. 

Contact information is provided under Technical Assistance in the Resources section, page 10.

soil amendments, plants, contaminants and their health 

website: www.clu-in.org/ecotools/urbangardens.cfm.
10 Urban Gardening

Resources for Urban Gardeners

Technical Assistance

1. Local agricultural cooperative extension services can help with interpreting soil quality results (i.e., pH 

and nutrients testing) and provide a list of local environmental departments or laboratories that test for soil 

contaminants. U.S. Department of Agriculture extension services are listed online at: www.csrees.usda.gov/

Extension/index.html. 

2. EPA’s Technical Assistance to Brownfields (TAB) program can help with questions regarding Phase I and 

Phase II Environmental Assessments. The TAB website is available at: www.epa.gov/brownfields/tools/index.htm#tab. 

In addition, several TAB providers have experience working with communities to explore urban agricultural 

opportunities. These providers include:

• Kansas State University: www.engg.ksu.edu/chsr/outreach/tab. 

• Center for Creative Land Recycling (especially in California and Colorado): www.cclr.org. 

3. State and tribal brownfields programs may be able to help with information specific to your state or tribe. 

To find your state brownfields program, visit: www.epa.gov/brownfields/state_tribal/state_map.htm. To find your tribal 

brownfields program, visit: www.epa.gov/brownfields/state_tribal/tribe_progs.htm.

10 Urban Gardening

Case Study

LIBERTY LANDS

Philadelphia, Pennsylvania

Twenty years ago, the Northern Liberties neighborhood was the only 

zip code in Philadelphia without a community green space. Several 

tanneries contaminated the neighborhood. EPA conducted removal 

actions and cleaned up the site. Neighborhood residents worked with 

the City of Philadelphia to find resources for reusing the site. EPA 

provided soil testing and other technical assistance to ensure that the site 

was safe for reuse as a park and community garden. Hundreds of hours of 

donated time, monthly meetings, outreach and fundraising efforts resulted in 

Liberty Lands community park becoming a reality. The park opened in 1996 and 

includes 37 garden plots and a composting area, an herb and butterfly garden, a children’s playground, open 

space for community events, and community art and sculpture. The park is at the center of a revitalized 

community, surrounded by new residential and commercial redevelopment.

For more information, visit www.epa.gov/brownfields/success/libertylandspass.pdf. 
Spring 2011 11 

Additional Resources 

General Information

More information about creating an urban garden is available at: www.epa.gov/brownfields/urbanag/.

More information on soil science, soil amendments, plants, contaminants and their health effects, and additional links can 

be found on EPA’s CLU-IN website, available at: www.clu-in.org/ecotools/urbangardens.cfm. 

Soil Quality

More information on soil health is available at: 

• EPA’s Hazardous Waste Cleanup Information website: www.clu-in.org/ecotools/soil.cfm. 

• Cornell’s Waste Management Institute website: http://cwmi.css.cornell.edu/soilquality.htm. 

• Local agricultural cooperative extension services website: www.csrees.usda.gov/extension.

Contaminants

The EPA Sector Notebook Series is a set of profiles containing information on specific industries. The notebooks can help 

your community identify types of contaminants often associated with specific commercial and industrial land uses. The 

notebooks are available at: www.epa.gov/compliance/resources/publications/assistance/sectors/notebooks/index.html.

EPA’s Toxics Release Inventory System provides useful information about the history of individual sites: www.epa.gov/tri/. 

Information about the health effects of particular contaminants is available at:

• The Agency for Toxic Substances and Disease Registry (ATSDR): www.atsdr.cdc.gov/substances/index.asp.

• EPA’s Integrated Risk Information System (IRIS): www.epa.gov/IRIS.

• The Risk Assessment Information System: http://rais.ornl.gov. 

In addition, EPA’s Superfund Redevelopment Initiative website has a web page where reuse questions can be submitted: 

www.epa.gov/superfund/programs/recycle/contact/index.html. 

Techniques for Addressing Soil Contamination 

For more information on techniques for addressing soil contamination: 

• EPA fact sheet: Soil Amendments for Remediation, Revitalization and Reuse Tools: Fact Sheet, available at: www.

clu-in.org/download/remed/540R07013.pdf.

• EPA paper: The Use of Soil Amendments for Remediation, Revitalization and Reuse, available at: 

available at: www.clu-in.org/download/remed/epa-542-r-07-013.pdf.

• EPA paper: Urban Agriculture and Soil Contamination: An Introduction to Urban Gardening, available at: 

available at: http://cepm.louisville.edu/Pubs_WPapers/practiceguides/PG25.pdf. 

• EPA fact sheet on brownfields redevelopment and local agriculture, available at: 

available at: www.epa.gov/brownfields/success/local_ag.pdf. 

• EPA’s fact sheet on phytotechnologies, available at: www.cluin.org/download/remed/phytotechnologies-factsheet.pdf. 

Funding Opportunities

More information on funding sources for brownfields assessment, cleanup, revolving loans and environmental job training 

is available at: www.epa.gov/brownfields/grant_info/index.htm.

EPA’s fact sheet on how to apply for Brownfields Assessment Grants is available at: www.epa.gov/brownfields/grant_info/

assess/assessment_factsheet.pdf. 
United States Environmental Protection Agency

Office of Superfund Remediation and Technology Innovation (5204P)

1200 Pennsylvania Avenue, N.W.

Washington, DC 20460

EPA 542/F-10/011 | Spring 2011 | www.clu-in.org/ecotools/urbangardens.cfm

Printed on 100% recycled/recyclable paper 

with minimum 25% post-consumer fiber.

Learning about and taking steps to assess and address potential 

contamination can help you to ensure that your urban garden area 

is safe and productive. You can reap the benefits for years to come.