Adding Manure to Gardens

“When is the best time to put cow manure on your vegetable garden?” Question from Sylvia of Belle Plaine, Minnesota

Answer: Be careful when adding manure to your beds. Fresh manure is too “hot” with nutrients, particularly ammonia, to put directly around growing plants and can literally burn their foliage and roots. Fresh manure is also filled with weed seeds just ready to germinate and cause havoc in your beds. That’s why it is necessary to compost it before use.

During the composting process the manure will heat up, causing weed seeds to die, and some nutrients to be leached away, making it a better garden soil additive. Composted manure can be added to beds at any time as a top dressing or soil amendment, but most gardeners like to beef up their soil in spring, just before planting time.

To compost your manure, place it in a compost bin or pile it up to a depth of at least 4 feet. Keep the pile lightly moist and turn it every couple of weeks or so with a pitch fork. Feel free to mix in any additional organic matter, such as grass clippings or crushed leaves, to the mix. The addition of Black Gold Earthworm castings will further enrich your manure compost.

Maturing manure should be hot enough in the middle to steam, even in winter. So, if your pile is steaming up, you are doing the right thing. After several months, your manure will lose its harsh smell and adopt the scent of fresh earth. At this time, it is ready to use!

Let us know how your manure composting progresses. Happy gardening! Jessie Keith


Plants are the lens Jessie views the world through because they’re all-sustaining. (“They feed, clothe, house and heal us. They produce the air we breathe and even make us smell pretty.”) She’s a garden writer and photographer with degrees in both horticulture and plant biology from Purdue and Michigan State Universities. Her degrees were bolstered by internships at Longwood Gardens and the American Horticultural Society. She has since worked for many horticultural institutions and companies and now manages communications for Sun Gro Horticulture, the parent company of Black Gold. Her joy is sharing all things green and lovely with her two daughters.

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