Protect your vegetable garden from contamination

Reports of food-borne illnesses are increasingly frequent in the news. Most foodborne illnesses are caused by consuming raw fruits and vegetables that are contaminated by pathogens. Pathogens are disease-causing microorganisms such as bacteria or viruses. Many people do not realize that home gardens are not free from pathogens.

Many fruits and vegetables have natural barriers, such as skins or rinds, which protect the edible parts of the plants from contamination. Vegetables and fruits that do not have a skin or rind that we remove, such as lettuce, spinach, berries and herbs, are the most susceptible to contamination by pathogens. But melons can also be risky if we don’t wash the rind before cutting into the fruit.

While chickens are great at helping with insect pest control, their droppings could contaminate a vegetable garden. Photo by Jennifer Kintz.

Many beneficial microorganisms reside in the soil and are necessary for plant growth; however, pathogens from outside sources can contaminate the soil and cause illness. Once contaminated, removing the pathogens from the soil and vegetable plants is difficult, so it is important to try to prevent contamination in the first place.

Water is one of the most likely routes for contamination. If your water is from a surface water source open to the environment, such as a pond, ditch or rain barrel, it is important to consider quality of the water before applying it to fruits and vegetables you plan to eat raw. Do not use graywater, or wastewater from baths, showers, clothes washers or sinks, in the vegetable garden. You could be introducing a pathogen. Always use pathogen-free water for irrigating the edible portion of plants and when rinsing the fruits or vegetables before consumption.

Animal fecal contamination is another source of pathogens in the vegetable garden. Birds, rabbits, mice and other wildlife are attracted to our gardens, and most leave droppings behind. Additionally, pets and livestock can contribute to possible contamination. Cats are notorious for seeing raised vegetable garden beds as litter boxes. The increasing prevalence of backyard poultry can also be a source of contamination. While chickens and other poultry can be great at consuming insect pests, they will also consume many vegetable garden crops and leave behind droppings. For more information, visit University of Nevada Cooperative Extension’s publication “Using Chicken Manure Safely in Home Gardens and Landscape,”

Many people will add non-composted manures or partially-composted manures to their vegetable garden. This can significantly increase the possibility of introducing pathogens to the vegetable garden. Hot composting manures before adding them to the vegetable garden is the best method to reduce pathogens. These manures can be a good source of nutrients for the garden, but compost them first to minimize your risk of introducing pathogens. If you must add partially-composted or non-composted manures to the garden, or anywhere in the landscape, bury them in the soil away from your plants. Don’t place them on the soil surface, where rain water or irrigation can cause the pathogens to spread to plants. For more information, visit Cooperative Extension’s publication “Composting Yard and Vegetable Wastes,”

Use care in the home garden, especially around those crops you plan to consume raw. Be aware of potential risks, and work toward minimizing the chance for contamination by pathogens in your home garden.


Melody Hefner is the Urban IPM and Pesticide Safety Program coordinator for University of Nevada Cooperative Extension. Have a gardening question? Contact a master gardener at 775-336-0265 or