Life expectancy of vegetable and flower seeds

As a Master Gardener, I give talks at libraries and garden clubs on starting plants from seed. A frequent question I receive is ‘how long can I save seeds? With that in mind, I am writing this article on the life expectancy of vegetable and flower seeds. However, the real question to consider is ‘will my saved seeds germinate?’.

Before we get into life expectancy, here are a few best practices when it comes to seeds:

• Don’t buy more seeds than you need for the current growing season
• When buying seeds, purchase seeds that were packaged for the current growing year (e.g., seeds less than one year old). By law, all seeds need to have a date on the seed package.
• Use seeds quickly after opening the package

Next, let’s look at two factors that dramatically impact seed life expectancy. First is the biology of seeds. The second is seed storage considerations.

The biology of seeds

A seed or embryo is amazing because it contains all the nutrients necessary to develop into a plant. However, over time those nutrients are consumed, and when consumed the seed embryo must either grow or it will die. Furthermore, different varieties of plant seeds and even seeds within a single seed package consume these nutrients at different rates leading to viability in seed germination. Or, said another way, nutrient consumption impacts how long a particular seed can be saved.

Seed storage

In general, seeds need to be stored in a dry and cool location to maintain nutrients. Considerations for seed storage are temperature, moisture, and consistency.

• A temperature between 32° and 41°F is perfect. Storing seeds in the refrigerator is the option I choose.
• To keep seeds dry, store unused seeds in their original package and then place them in an airtight container. It also helps to add a silica-gel desiccant to the container to absorb moisture.
• Lastly, store in a location that is consistent regarding temperature and moisture. For example, the garage or a basement are not good places to store seeds because the temperature and moisture level are inconsistent over time.

Remember, seed storage will impact the viability in future years.

What can you expect as seeds age?

The US Department of Agriculture sets standards on seed germination rates for growers. Many times, the expected germination rate will be listed on the seed package. For example, if a seed package indicates a 90% germination rate, that means that 9 out of 10 seeds in the package should germinate. As seeds age, the germination rate will decrease. To be conservative, I assume a 50% germination rate for seeds that have aged one plus years. At a 50% germination rate, only 5 out of 10 seeds will germinate. This simply means you need to use more seeds to get the same number of plants.

If you have a good quantity of saved seeds, you may want to perform a germination test. Here’s a good resource from the University of Michigan Extension for how to do a germination test.

Viability of seeds – vegetables

Now, we look at a comparison of how long vegetable seeds can be saved based upon three different resources. While there is general agreement across the three resources, there are also a few exceptions. Lettuce stands out as a rather significant difference. I don’t have a research-based explanation for the difference in lettuce seed viability. However, what I did notice is that earlier research (1970s) of lettuce seed viability indicated that lettuce seed is only viable for one year. Today, newer varieties of lettuce can be stored for a longer period.

Viability of seeds – flowers

Next, we look at a seed viability chart for some common flowers based upon information from two different seed companies. Again, while there are a few differences, nothing is significant.

As a home gardener, it will be inevitable that seeds will need to be stored for future use. By following the storage guidelines on temperature and moisture, you should have good success with saving seeds for a few years. I hope this article has demystified the life expectancy of vegetable and flower seeds.

In addition, you might also be interested in the following articles:

• Five steps to starting a vegetable garden
• The complete guide to starting seeds indoors
• Understanding the USDA Plant Hardiness Zone Map
• Using first and last frost dates to plan your garden
• How to create a productive small vegetable garden

References

Purdue University “Storing Leftover Garden Seed”

Colorado State University Extension “Storing Vegetable and Flower Seeds”

High Mowing Organic Seeds “Seed Viability Chart”

Johnny’s Selected Seed “Seed Storage Guide”

Clear Creek Seeds “Seed Viability Chart”