Why Grass Seed Goes Bad— And How To Work Around It

If you’re looking to manicure your lawn, athletic field, golf course, or any area requiring grass in time for summer, a question has likely crossed your mind: “Does grass seed go bad?” After all, the last thing you want to happen after taking the time to sow your grass seed is to notice that only a few (or none) of your seeds sprouted and, therefore, have to invest even more time and money into your lawn (when it could have been easily avoided). Luckily for you, we gathered some experts to provide some insights so you can do your best to ensure your grass seed is in top form.

Ahead, landscape professionals, turfgrass specialists, and professors weigh in on the question of whether grass seed goes bad, along with insights on grass seed longevity, the factors that cause grass seed to go bad, the signs to look for, and what you can do to prevent grass seed from going bad.

Does Grass Seed Go Bad?

Yes, grass seed goes bad. After all, grass seed is living and will die if not cared for properly. When grass seed “goes bad,” it simply means it can no longer germinate and grow, notes Michael Fidanza, a professor of plant and soil science at Pennsylvania State University.

Why Does Grass Seed Go Bad?

In addition to the physiological explanation that grass seed goes bad over time because it is living, some other factors can expedite the process if not carefully monitored. “Temperature, moisture and humidity, and bacterial and fungal pathogens all can affect seed function and growth,” Fidanza tells Family Handyman.

Jon Trappe, a turfgrass extension educator at the University of Minnesota, notes that grass seed that is not stored in a cool and dry environment is more likely to go bad (and therefore lose its viability) and grow mold. If you keep your grass seed in a warm and humid environment with lots of exposure to direct sunlight, Fidanza explains that it will overheat and fail to germinate.

How Long Does Grass Seed Last?

Although grass seed doesn’t have a set expiration date, Grady Miller, an ENVU-distinguished professor of sustainability and extension specialist at North Carolina State University, notes that you can generally expect it to last a few weeks to decades (depending on how well it is stored and cared for).

That said, Amanda Folck, an assistant extension educator of turfgrass management at the University of Nebraska-Lincoln, notes that the type, quality, and species of grass seed can impact its lifespan. It is important to note that “how much of the grass seed will germinate will gradually go down over time,” adds Trappe.

Signs Grass Seed Has Gone Bad

Although you won’t officially know whether or not your grass seed has gone bad and is unable to germinate until you’ve planted (and/or tested its germination rate), there are several signs you can pay attention to that will give you an idea of the chances. In general, Bob Mann, the senior director of technical and regulatory affairs of the National Association of Landscape Professionals, notes that the older the seed (which can typically be determined by referring to the test date on the bag), the higher the likelihood that it has gone bad.

Mann adds that if you notice any fungi atop the seed and/or holes or droppings inside the seed bags, there’s a good chance that the grass seed is contaminated— and, therefore, less viable (or not viable at all). Furthermore, grass seed that’s gone bad can be accompanied by an unpleasant odor and appear brittle, clumpy, and discolored, notes Fidanza.

How To Prevent Grass Seed From Going Bad

Even with the unfortunate answer to the question “Does grass seed go bad?” being yes, there are several actions you can take to prevent that from happening and/or slow down the deterioration rate. If you need to store your grass seed, Trappe recommends doing so in cool and dry environments between 40-75°F and keeping it out of warm and humid ones with direct sunlight. In some cases, properly freezing grass seed can also be helpful when it comes to preserving its viability.

You also want to store grass seed in areas where pests cannot contaminate and/or eat it (the original bag or sealable plastic bucket make good options), adds Mann.

That said, one of the best ways to prevent grass seed from going bad is to use it as soon as possible. “Sow the seed within a year (of its test date) to ensure the best chances of maximum germination and growth,” advises Fidanza.

About the Experts

• Bob Mann is the senior director of technical and regulatory affairs of the National Association of Landscape Professionals. He has been an active member of the professional lawn care industry for more than 30 years and previously served as the president of the Massachusetts Association of Lawn Care Professionals.
• Michael Fidanza, Ph.D., has been a professor of plant and soil science at the Pennsylvania State University for the last 25 years. In addition to his role as a professor, he is currently an American Society of Agronomy Fellow and edited the “Achieving Sustainable Turfgrass Management” textbook in 2023.
• Grady Miller, Ph.D., is an ENVU-distinguished professor of sustainability and extension specialist at North Carolina State University. As someone who routinely evaluates turfgrass germplasm, he is knowledgeable about grass seed and has used his expertise to publish more than 750 articles on turfgrass management while serving as an Agronomy Society of America Fellow.
• Amanda Folck is an assistant extension educator of turfgrass management at the University of Nebraska-Lincoln. Since 2023, she has been helping educate students within the Agronomy and Horticulture Department.
• Jon Trappe, Ph.D., is a turfgrass extension educator who has been working with the University of Minnesota since 2023. With more than 20 years of experience in the turfgrass industry, he has been able to develop a wide understanding when it comes to preserving seed viability and the best turfgrass management practices.

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