Do Garden Seeds Go Bad?

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Saving seeds and using leftover seed packets from previous seasons is a common and practical gardening practice. But many gardeners wonder: do garden seeds go bad?

The short answer is yes. Garden seeds can lose their viability over time. However, how quickly this happens depends on several factors, including the type of seed, how it’s stored, and its age. Understanding seed longevity and how to properly store your seeds can help you make the most of your garden investments and ensure you’re planting seeds that will actually grow.

Can Seeds Go Bad?

Yes, seeds can go bad. While seeds aren’t food, they are living organisms in a dormant state. Inside every seed is a tiny embryo with stored nutrients, waiting for the right conditions, moisture, warmth, and air, to grow into a new plant.

Over time, if not stored properly, seeds can lose their ability to germinate. They may dry out too much, become moldy, or simply degrade due to age and environmental stress. They can also get too hot and die that way. Ask me about when I used to store my seeds in the hot garage…

“Going bad” for seeds doesn’t usually mean they rot or spoil in the way food does. Instead, it means they lose viability, or the ability to sprout and grow.

Do Seeds Go Bad Over Time?

Even under ideal storage conditions, seeds gradually lose their vigor and germination rate as time goes on. How long seeds stay viable varies widely between plant species. Some seeds, like tomatoes or cucumbers, can remain viable for 4 to 6 years, while others, like onions or parsnips, may only last one year before their germination rate drops significantly.

Below is a general guide to how long various types of garden seeds remain viable when stored properly:

• 1 Year: onions, leeks, chives, parsley, parsnips, corn
• 2-3 Years: carrots, beans, peas, peppers, spinach
• 4-5 Years: tomatoes, cucumbers, squash, melons, radishes
• 5+ Years: lettuce, kale, cabbage, beets, turnips

Keep in mind that these are averages. Individual seed packets may last longer or shorter depending on their original quality and how they’ve been stored. Also, germination rates gradually decline, so older seeds may still sprout, but fewer of them will.

Factors That Affect Seed Viability

Several environmental conditions can affect how long seeds remain viable. Understanding these factors can help you make decisions about storing, using, or discarding older seeds.

1. Temperature: Seeds should be stored in a cool, consistent temperature. Excessive heat shortens seed life dramatically. A temperature between 32°F and 50°F is ideal for long-term storage. A refrigerator is a great option for storing seeds over multiple years. Also, the freezer is a good place. I have my survival seed bank in the freezer in mylar. I have my regular seeds I use stored in a tote under my bed on the floor, where it stays cooler.
2. Humidity: Moisture is a major threat to seeds in storage. High humidity can cause seeds to mold or sprout prematurely. Seeds should be stored in an environment with less than 50% relative humidity, and even lower is better. Using silica gel packs or other moisture absorbers in your seed containers can help. I save them out of new shoes and purses and place them in the containers my seeds are in.
3. Light: Light can trigger changes in seeds that may reduce viability. Store seeds in opaque, airtight containers that block light, such as glass jars or metal tins with tight-fitting lids. Under the bed or in the closet on the floor is great for this reason as well.
4. Air Exposure: Oxygen can slowly degrade seeds over time. Airtight containers reduce oxygen exposure and extend seed life. If you’re storing seeds long-term, vacuum sealing or using oxygen absorbers is ideal. Mylar is the best for reducing air exposure. Mason jars work well too.
5. Seed Type: As mentioned, some types of seeds naturally last longer than others. Always consider what kind of plant the seed comes from when determining how long to store it.

How to Tell if Your Seeds Are Still Good

If you’re wondering whether your seeds from last year (or several years ago) are still good, there’s an easy way to test them before planting your whole garden. This is known as a germination test.

To do a simple germination test, follow these steps:

1. Dampen a paper towel and lay it flat.
2. Place 10 seeds evenly spaced across the towel.
3. Fold the towel over the seeds and place it in a zip-top plastic bag.
4. Keep the bag in a warm spot (around 65–75°F) and check daily. The top of the fridge or freezer is great for this.
5. After 7–10 days, count how many seeds have sprouted.

If 8 out of 10 seeds sprout, that’s an 80% germination rate, which is very good. Even a 60% germination rate can be acceptable, you’ll just need to plant more seeds to ensure enough grow. If fewer than 50% germinate, it might be time to replace those seeds.

Proper Storage for Garden Seeds

How you store your seeds has a huge impact on their longevity. Even seeds that have expired based on the year listed on the packet can still sprout if they were stored in optimal conditions.

Here are some best practices for storing your garden seeds:

• Use Airtight Containers: Mason jars, vacuum-sealed bags, or plastic storage boxes with tight-fitting lids are good choices. Keep each type of seed in a separate labeled envelope or packet inside the container.
• Cool, Dark, and Dry Location: Ideal storage places include a dry basement, cool pantry, or refrigerator. Avoid garages or sheds, which often experience large temperature swings and higher humidity.
• Label Your Seeds: Make sure each packet is labeled with the plant name and the year it was packaged or harvested. This will help you track which seeds to use first and when to replace older ones. I keep my seeds in the original packets if possible for all of this information.
• Keep Out of Reach of Pests: Seeds attract insects and rodents. Store them in containers that prevent chewing or digging. Adding bay leaves to your storage area can help repel pests naturally.
• Use Desiccants: Small silica gel packets or powdered milk in breathable containers (like a small envelope) can help keep humidity levels low in your storage box.

Using Expired Seeds

Seed packets often come with an expiration or “packed for” date printed on the label. This date is typically about a year from when the seeds were packaged and reflects the time frame during which germination is expected to be highest. However, this doesn’t mean seeds are useless after that date.

If seeds have been stored well, they often remain viable for years past their expiration. When using expired seeds, you may want to sow more heavily or test germination first to avoid gaps in your garden rows. Expired seeds can also be used in children’s garden projects, microgreens, or as cover crops, even if the germination rate is low.

Saving Your Own Seeds

Gardeners who save their own seeds from year to year should be especially careful with storage. Seeds saved from healthy, open-pollinated plants are typically just as viable as store-bought seeds, if not more so, assuming they are dried and stored correctly.

Allow seeds to fully mature and dry on the plant before harvesting. Clean and dry them thoroughly before placing them into labeled envelopes. Store them in the same cool, dark, and dry conditions as purchased seeds. Be sure to save seeds from healthy plants that show the traits you want, and avoid saving seeds from hybrid varieties, which may not grow true to type.

When to Toss Old Seeds

Sometimes it’s best to just let go of old seeds. If seeds are more than five or six years old, especially if they’ve been stored in less-than-ideal conditions, their chances of germinating may be slim. Seeds that have been exposed to water, show signs of mold, or smell musty or sour should be discarded.

If a germination test shows fewer than half of your seeds are sprouting, it’s probably more trouble than it’s worth to try using them. Seeds are relatively inexpensive, and starting with fresh, vigorous seeds can give you a stronger, healthier garden with less work and worry.

Repurposing Old Seeds

If you find yourself with a large number of old or low-viability seeds, don’t toss them right away. There are some fun and useful ways to repurpose them:

• Feed birds or chickens: Many garden seeds are perfectly edible for wildlife. Scatter them in a feeder or toss them into your chicken run.
• Use for educational projects: Children can use old seeds for craft projects, pretend play, or science experiments. We love to make collages and mosaics out of seeds. They are so interesting and colorful.
• Grow microgreens: Even older seeds can sometimes produce microgreens, which don’t need a perfect germination rate. Spread them thickly on soil and harvest the young shoots after a few days.
• Create wildflower meadows or pollinator patches: Scatter expired flower seeds in a patch of land and see what comes up. Even if some don’t germinate, others might surprise you.