How To Properly Store Your Vegetable Seeds

Lucy Hutchings from heirloom seed company She Grows Veg is on hand to share her expert tips on preserving your precious seeds

Gardening enthusiasts and vegetable growers understand the importance of preserving seeds for future planting as well as making the most out of the seeds that have been purchased. Proper seed storage ensures that your efforts in sourcing, growing, harvesting and saving seeds do not go to waste. Sell by dates on seed packets can often be taken with a big pinch of salt and with the right techniques, vegetable seeds can remain viable for years, providing you with a sustainable source of plants season after season. Here are some tips on how to store vegetable seeds to maximise their longevity.

Start with Quality Seeds
Before diving into storage methods, it’s crucial to begin with high-quality seeds. Choose your initial source seed from a reputable supplier of high quality seed. Often with seed, you get what you pay for and seeds are cheap for a good reason. When saving seed, select seeds from healthy plants that exhibit the desired traits such as disease resistance, robust growth and high yield.

Ensure Seeds are Completely Dry
One of the most critical steps in seed storage is ensuring that seeds are kept thoroughly dry. Moisture is the enemy of seed longevity, as it can lead to mould, rot and reduced viability by breaking the dormancy of a seed, only for it to then be unable to grow. Store purchased seed in watertight containers if it is to be kept in a humid environment such as a garden shed. When harvesting seeds, spread them out on greaseproof paper in a well-ventilated area away from direct sunlight. Allow them to dry completely for at least a week. Larger seeds may require more time to dry fully.

Use Airtight Containers
Once your seeds are dry, store them in airtight containers to protect them from moisture and pests. Glass jars with rubber seals, vacuum-sealed bags, or specialised seed storage containers work well. Label each container with the seed type and date of storage for easy identification later.

Control the Temperature
Seeds store best in cool, stable temperatures. Ideally, store seeds in a cool basement, root cellar or refrigerator. A temperature range of 0-5°C is optimal for most vegetable seeds. Avoid storing seeds in areas with fluctuating temperatures, such as garages or sheds, as this can reduce seed viability. As an example of how much difference temperature can make, the sell by dates on tomatoes seeds are around two years on average. Tomato seed that is stored in an airtight container in the fridge is expected to have a viability of 15 years or more!

Maintain Low Humidity
In addition to cool temperatures, maintaining low humidity is essential for seed storage. Aim for a relative humidity of less than 50%. Use desiccants like rice in your storage containers to absorb excess moisture.

Avoid Light Exposure
Light can degrade seeds and reduce their germination rate over time. Store your seed containers in a dark place or use opaque containers that block light. If using clear glass jars, keep them in a dark cupboard or drawer. At the very least avoid direct sunlight at all costs as this will degrade seeds fastest.

Consider Freezing for Long-Term Storage
For those looking to store seeds for several years or even decades, freezing can be an effective method. Seeds must be thoroughly dried before freezing to prevent ice crystal formation, which can damage seed cells. Place seeds in airtight, moisture-proof containers before storing them in the freezer. When you’re ready to use the seeds, allow them to thaw gradually at room temperature before opening the container to avoid condensation.

Regularly Check Seed Viability
Even with the best storage methods, seed viability decreases over time. Regularly check the germination rate of your stored seeds by performing a simple germination test. Place a few seeds on a damp paper towel, fold it, and place it in a plastic Tupperware box. Keep the box in a warm spot and check for germination after a few days to a week. If the germination rate is low, consider using more seeds than usual when planting or replacing old seeds with fresh ones.

Know the Exceptions to the Rule
Unfortunately even with the best storage methods there are still some seeds that will only last a show time. Parsnips are the best example of this and must be sown from fresh seed harvested the previous year, as older seed will not germinate. Onions, parsley, salsify, spinach and carrots are all known to have shorter viability than other seeds though good storage methods will help to maximise this as much as possible.

Proper seed storage is an essential skill for any gardener aiming for self-sufficiency and sustainability. By following these tips, you can extend the life of your vegetable seeds, improve your seed security and enjoy bountiful harvests for years to come.

She Grows Veg is on a mission to help as many people as possible to grow their own food and feel the joy! Its extensive range of open-pollinated heirloom seeds is available from shegrowsveg.com

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