How to Store Seeds

You know spring is coming when you see those bright packets of seeds for sale in the market. But, like so many seasonal products, seed packets may appear many weeks before it is possible to plant anything.

Or you may be looking at your garden and noticing that your favorite plants are producing seeds on their own. Or you may have been gifted seeds by a plant-loving friend. In any case, how do you store seeds until the time is suitable for planting?

Why Does Seed Storage Matter?

Proper storage means controlling moisture, temperature, and light. These are the triggers for germination and also create conditions for mold. Taking good care of seeds means storing them in a way that maintains dormancy and increases the chance that most or all will germinate when planted.

How to Store Seeds

How you safely store seeds until planting depends on whether you have bought seeds or have gathered them on your own.

How to Store Packaged Seeds

If the seeds are pre-packaged, they’ll be labeled with dates harvested and plant-by-dates. Read the packet carefully. Then store the packages in a dark, dry, cool place till planting time.

How to Store Fresh Seeds from the Garden

If you have harvested seeds from a plant, here is how to store them:

1. Harvest and Clean the Seeds

To harvest seeds, collect them from vigorous, productive plants. The best time to harvest varies by species but look for well-developed and mature seeds, ready to drop from the plant by themselves. 

Be aware that if you collect seeds from hybrid plants, those seeds will not produce the same type of plant. You’ll get better results by collecting seeds from open-pollinating or heirloom species because the seed will more truly reproduce the plant it came from.

Like those from berries, tiny seeds can be collected by putting ripe berries in a jar with some water. Let them sit for a few days, giving the pot a shake from time to time. The seeds will separate and sink. Pour the liquid through a fine sieve or cloth, spread the pulp, and pick out the seeds. Lay them on dry paper towels.

Seeds from pulpy fruit like tomatoes, summer squash, and cucumbers can be separated and cleaned in the same way.

Plants such as peas, beans, and lupines make seed pods. The pods should stay on the vine till they are dry and brown. When the seeds rattle inside the pod, put the pods in a container such as a paper bag or a glass jar. Shake the container to separate the pods and chaff from the seeds.

Seeds from peppers and chilis separate easily from the mature vegetable. Be careful harvesting seeds from chilis because capsaicin can burn your skin. Winter squash, pumpkin, sunflower seeds, and many other flower seeds are also easy to harvest.

If you harvest seeds from stone fruits like plums or peaches, allow the seed to dry completely, then use a brush to gently scrub away any remaining fruit residue from the stone.

2. Dry the Seeds

Once seeds are harvested, they must be thoroughly dried. Moisture is one of the signals that trigger germination. But, unfortunately, it’s also the cause of mold. So it’s necessary that the seeds are completely dry when stored and that no moisture can get to them till they go into the soil.

To dry your seeds, spread them on dry paper towels or cloth, and turn them daily. A fan can be used to increase airflow and speed drying. Cautious use of a very short time in an oven, at a very low temperature (less than 38°C/100°F) or a food dehydrator, can speed the drying process.

However, there’s a risk of reducing the viability of the seeds by heating them, so only use those methods in highly humid environments where it is difficult to air-dry seeds.

Seeds are completely dry when they don’t bend or crush. A dry pumpkin seed, for example, will snap in two rather than bend. Small seeds may be dry enough to store in 2 or 3 days, depending on conditions such as humidity. However, large seeds may need a week or more to be thoroughly dried.

3. Store Seeds Until Planting Season

Once your seeds are dry, follow these steps:

• Label an envelope with the plant’s name, light and water requirements, and optimal planting season.
• Place your seeds into the correct envelope
• Place the envelopes in a glass jar. In humid environments, add a desiccant pack, a spoonful of rice, or powdered milk to the jar to absorb moisture and keep the inside of the jar dry.
• Tightly seal the jar
• Store the jar in a cool, dry place with a consistent temperature. Warmth and light may trigger premature germination of your seeds. A cellar or basement is a great place to store seeds. If they are in a pantry or cupboard, make sure they aren’t exposed to significant temperature changes.
• Sort your jars by planting date. Then, group the jars by when the seeds inside should be planted so that you can plant all your late winter, early spring, and spring seeds at the right time.

How to Store Moist Storage Seeds

Some seeds germinate better when they have been stored in moist conditions. This is called moist stratification. Milkweed, apples, stone fruits, and asparagus are just a few plants that get a better start when their seed is stored this way because it simulates natural winter conditions. Look up the requirements of the species you’re working with to see what is best for your seeds.

Place clean seeds in a plastic bag full of damp (not wet) sawdust, sand, or peat to store seeds that need moisture. If the seeds are very small, place them on a damp paper towel. Fold the towel over and put it in a plastic bag.

Store in a cool, dark location such as the back of the refrigerator. Check them from time to time to make sure they are still dormant. If you see that a seed is germinating, get it into the soil.

Conclusion

For best results, all seeds should be planted within a year of harvesting. For pre-packaged seeds, refer to the expiration date. Storing your seeds in the right way helps ensure you get great plants in the springtime.