Old seeds: how to check viability and what to keep in reserve

Over time, seeds gradually lose their ability to germinate. The rate of deterioration is influenced by the type of plant and storage conditions: heat and humidity accelerate aging, while dry and cool conditions help preserve viability longer.

However, the shelf life varies among different plants. With proper storage, you can refer to the following estimates:

Onions and pasternak— approximately 1–2 years. It’s better to replace their seeds more frequently.
Peppers, peas, and beans— usually around 2–3 years.
Carrots— about 3 years.
Tomatoes and pumpkins— around 4 years.
Cucumbers and radishes— up to 4–5 years.

These are guidelines, not fixed dates after which seeds stop sprouting. Even an old packet of tomato seeds can produce good sprouts if stored properly. Meanwhile, seeds from a relatively new packet may sometimes be weak after being stored in hot and humid conditions.

Therefore, while the date on the packet should be considered, it’s best to make a final decision based on testing results.

A simple method recommended by university horticulture services works well for most vegetable crops.

Take 10 seeds from one packet. If possible, test 20 seeds for more accurate results.
Spread them on a moist paper towel and cover with another layer. The paper should be damp, but no water should drip from it.
Place the towel in a transparent container with a lid or bag to prevent it from drying out. Note the crop type, variety, and date the testing began.
Keep it at a temperature suitable for the growth of the selected plant. Check the moisture level and the appearance of roots periodically.

For many vegetables, the first signs of growth appear within 7–10 days. However, some plants take longer. Refer to the germination time indicated on the packaging.

Important note: this test is not suitable for all seeds. Some perennial flowers require cold stratification before germination, while others need light. If such seeds do not germinate on the tissue paper, it does not mean they are dead.

If you tested ten seeds, it’s easy to calculate the result.

8–10 seeds sprouted. The batch can be kept and used for regular planting. In this case, old seeds should also be evaluated for seedling quality: weak and deformed plants don’t always produce good seedlings.
5–7 seeds sprouted. The germination rate is low. You can use more seeds than usual for planting, but for valuable varieties or limited numbers of seedling trays, it’s better to buy fresh seeds.
Fewer than five seeds sprouted. It’s more advisable to replace the batch, especially for tomatoes, peppers, and other crops where it’s important not to miss the optimal timing for growing seedlings.

The popular test using a glass of water does not replace germination testing. Seeds may float or sink for various reasons, and this indicator cannot reliably determine whether sprouts will appear.

It’s not worth spending time on packets containing seeds that are moldy, damp, or have a musty smell. Unknown seeds without labeling should also be avoided for main seedlings: even if they germinate, it will be difficult to determine the variety and growing conditions.However, a torn package alone isn’t reason to discard everything. If the seeds remain dry, they can be checked and transferred to a labeled paper envelope.

A dry, cool place without drastic temperature changes is suitable for storage. Envelopes can be stored neatly in a sealed box with a packet of silica gel to prevent excess moisture. Seeds collected by yourself need to be thoroughly dried before packaging.

Each packet should have the name of the culture, variety, and year of harvest or purchase written on it. This way, you won’t have to guess again next winter how old an unknown packet is.

The most useful thing about a December review is not to throw away all the old items, but to check suspicious batches in advance. Ten to twenty seeds and a little time will help you determine what will still be useful in spring and what is better to buy anew.