How To Store Seed Packets Properly

How long do seeds last? This is the one same question that gardeners seem to ask over and over and unfortunately there is no definitive answer. You might as well ask, “how long is a piece of string?” because there are a number of factors, which need to be taken into consideration when determining the life expectancy of a seed. It will first depend on the type of plant, as every seed type is different.

Much depends on the actual time the seeds were harvested and how long they were exposed to the elements before finally being packed. Then, you have to take into account how long the seeds have been in storage before they actually reach you, the gardener. All these factors have a part to play in the viability of a seed. However, here are some pointers, which will help you to understand how to store your seeds properly, allowing you to reap a longer bountiful harvest for your initial investment.  

1. What is a plant seed?

A plant seed is a living organism. It is an embryo encased in an outer protective shell called a seed coat, and it is in a dormant state until presented with the right conditions, with which it will germinate and subsequently grow. Also, within the seed coat is a small amount of stored food, enough to sustain the young plant during its emergence and until it can form its feeding roots and leaves. Like all living organisms it has a life span or viability period, after which it will die unless preserved with care.

2. Always buy fresh, quality seeds

Despite what might have happened before, during and after harvesting of any particular seeds, which is out of your control, it is always advisable to initially buy fresh seeds. That simply means buying from a reputable seed merchant and not from some car boot sale or charity shop.

Seed growers have a reputation to maintain so it’s in their interests to grow strong, healthy and virus free parent plants, from which to harvest quality seed. Seeds collected from the best plants will undoubtedly produce the best quality plants for your garden or vegetable plot.

3. Check the dates

When buying fresh seeds always check the dates on the packet. Each packet should at least display the date they were packed and some may also display the ‘use by’ date. However, this ‘use by’ date is not set in stone, it’s more of a guide as to the longevity of the seed’s life or its viability to germinate. It doesn’t mean the seed will not grow after this date providing it is stored correctly. Also, many seed types are now foil packed for freshness and to preserve their vitality. Seeds purchased in resealable packets are highly recommended as opposed to those in paper packets.

4. Only use what you need

Knowing that your seeds may keep throughout the growing season and beyond, only sow what you need at any one time. Many gardeners will sow vegetable seeds for example, at 2-4 week intervals to ensure they have a steady supply of fresh vegetables throughout the growing season. Lettuce is a quick growing plant and is a prime example for sowing little and often throughout the spring and summer months.

By using only enough seeds to get you through the season, you may well have seeds left over, which if stored properly will be perfectly okay to use the following year. However, the rate or percentage of continued successful germination is all about the storage method.

5. What to do with unused seeds

It’s easy to forget about the leftover seeds and to leave them lying around in a shed or greenhouse only to degenerate. If you plan ahead and think about the leftovers before you start sowing then you will be well prepared to make the most of your small investment. After each sowing, ensure the seed packet is resealed, then store in a cool, dry place.  

6. What not to do with unused seeds

Do not leave unused seeds in a greenhouse, where there will be fluctuation in temperatures and humidity during periods of the day and night. Do not empty your seeds into a jar or tin and then leave them exposed to direct sunlight. A damp shed is also not a good place to store seeds because the humidity can affect the seed’s overall life expectancy.

Some horticultural institutions will store seeds in a deep freeze facility but generally this will involve the use of Nitrogen or Carbon Dioxide (dry ice). This process is also known as cryogenics and involves working with temperatures as low as -78°C. You might think then that storing your seeds in your home freezer or refrigerator would help preserve them but unfortunately there is just too much moisture (water) present to ensure this method will be truly successful.

7. Why seeds lose viability

Without getting into too much technical information, suffice to say that seeds start to degenerate from the moment they are harvested. This is of course in miniscule degrees but the process will then continue until the seed eventually dies. The reasons why this happens is why you should know how to store seeds in the right conditions.

One influence on seed degeneration is sunlight, which is a bit of a contradiction when you consider that the maturing seeds need sunlight in order to develop and mature. However, over exposure to sunlight after harvesting can have a detrimental effect on the seed. Another factor to take into account is air, in particular moist air. When you consider that a seed needs water in order to germinate, then moisture will certainly affect a seed’s viability. Finally, temperature will play a part in the degeneration process. A warm atmosphere will cause the seed’s ability to degenerate faster than a cool temperature.    

8. Flower seeds or vegetable seeds – which will last longer?

There is no distinction between the longevity of a flower seed and a vegetable seed. Much depends on the type of plant. Also, large seeds and small seeds are equally indistinct when it comes to which one will last longer. The general rule for annuals is that most will last 1-3 years and for perennials it can be a bit longer at 2-4years. There are of course one or two exceptions to this rule, as some gardeners will testify, but as a general guide, these time periods can be expected, providing the seeds are stored in the correct manner.

For most vegetable seeds, again depending on type of vegetable, a period of 2-4 years can be expected with a few exceptions either side of this. For example, cucumber seeds can be stored for up to 5 years and courgettes up to 7 years, whilst onion and parsnip seeds are past their best after just one year. In all cases what will generally happen is that the percentage of germination will fall off as the seed gets older. With this in mind, if you are sowing seeds that are more than one year old then simply sow more but expect less plants as times goes on.

You can always test the viability of seeds by placing 4-5 randomly selected seeds on a wetted tissue or cotton wool and leaving them in a warm sunny position, like a windowsill. Then, wait and see how many actually germinate. If none of them do, you can assume it’s time to buy new, fresh seeds.

9. How to store all seeds the right way

All the information provided in this article is intended as a guide, which you should find useful. However, what it all comes down to is how you actually store your seeds. From the information provided it should now be obvious that proper storage of seeds will keep them viable over a relatively long period of time. The main points to remember then is to always start with fresh quality seeds. All seeds should be stored in a cool, dry and dark place, preferably in an airtight container. It’s also best if the place of storage has a fairly stable temperature and does not fluctuate too much during certain times of the day.

If the storage of all seeds is done correctly, then there is absolutely no reason why they shouldn’t last for a number of years, providing you with continuous crops and real value for money.

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