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Do you have old seeds you haven’t got around to planting? If they are out of date, you may be wondering if you can still sow them. Most gardeners have good intentions when buying seeds, but then life happens! Rather than wasting money you’ve spent on expired seeds, why not test their viability to see if there’s any life left in them? You may be pleasantly surprised.

Can you sow out of date seeds? How to test seed viability and store seeds safely

Out of Date Seeds

Seeds, like other living things, have a shelf-life! Just because seeds are out of date, doesn’t mean they won’t germinate and grow normally. Don’t get rid of them yet! Checking your seeds is much more sustainable than throwing them out and assuming they are useless. I’ll show you an easy way to test them. So you won’t waste time and effort planting the packet if they’re not going to grow.

If the seed packet date has expired, it’s similar to the ‘Best Use By’ date on food packaging. It doesn’t mean the food isn’t edible, but the quality may have deteriorated. Likewise, some of the seeds may still grow if planted, but not necessarily every seed in the packet. The longer you wait to sow, the lower the chance of successful seed germination.

How Long will Seeds Last?

The lifespan of a seed is tricky to answer because it depends on several factors. These are a few to consider.

1. How the seeds have been stored. Exposure to heat, light and humidity will decrease the life of seeds. If, on the other hand, they have been kept in your fridge (<5°C or <40°F) in a dark sealed container with <10% moisture, some seeds could live up to 10 years and even longer.

2. The type of seed and plant variety. Some seeds naturally have a shorter shelf-life than others. For example, the onion family and parsnips typically only last a year, so need to be used quickly. Whereas basil, radish and cucumber seeds can last an average of five years, with many vegetables and herbs in between! On average if stored properly, most herb and vegetable seeds will last up to 3 years.


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3. How old the seeds are. You can expect to get at least a year out of new or freshly saved seeds, but many will last for several years if stored correctly. If you bought seeds with a short use-by date, this may limit how long they will stay viable for.

4. Quality of the original seed. Seeds I’ve saved from my own garden tend to last much longer than purchased seeds. Why? Because they are fresh and viable from the moment that I store them. I also carefully select only the best quality from strong healthy plants.

Best Time to Test for Seed Germination

Temperature

This is an important factor to consider before testing to see if your seeds will germinate. Check your seed packet for information on the ideal temperature range for sowing. Seeds germinate when their unique conditions are met. Warmth and moisture (humidity) need to be right.

Your seed packet or catalogue will provide soil temperature and seasonal details of the best time to sow seeds

If for example, your old seeds are best sown in a warm season between 20-25°C (68-77°F), and the temperature is suitable in your current season, you’re good to test them. However, if you are in the middle of winter, it’s unlikely they will sprout even if they ARE still viable! Way too cold to wake these babies up unless you can put a heat mat under them or move them somewhere warm enough for testing. If they germinate, you’ll have to raise them in a warm environment until you’re ready to transplant.


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Light vs Darkness

Check if the seed variety requires light or darkness to germinate. You will need to follow the specific directions for what you want to sow. If the seeds require darkness, you will need to cover them and put them in a dark spot when doing your testing.

How to Test Seed Viability in 3 Easy Steps

Once you’re ready to test if your seeds are still alive and have the vitality to grow healthy plants, follow this simple process to check their viability.

With a few basic materials, you can easily test your seed viability

With a few basic materials, you can easily test your seed viability

You’ll need: Seed packets; paper towels/napkins or seed raiser with seed raising mix*; water in a spray bottle; recycled plastic bag; marker pen to label the bag; patience (seriously)!

* If you don’t have a paper towel handy, you can sow the seeds into seed raising mix in a seed raiser with a lid.

Recycle 2 containers the same size to enclose a punnet with your seeds as an alternative for viability testing

Recycle 2 containers the same size to enclose a punnet with your seeds as an alternative for viability testing

Step 1: Prepare to Sow

Firstly, do a visual check and choose 10 of the best looking seeds. Avoid selecting any that are shrunken, mouldy or discoloured. Set seeds aside.

Save the best quality seeds for testing seed viability. Avoid damaged, mouldy or discoloured seeds.

The bean seeds on the right are plump, large and have stored well. The ones on the left are discoloured and small.

Spray a paper towel or serviette with water to dampen well. Lay flat on a surface and on one half, spread out your seeds so they are well separated. Fold the other half of the paper towel over the top of the seeds to cover.

* Alternatively, sow seeds into compartments in your seed raiser, fitting the lid tightly.

Step 2: Store Seeds Correctly

Slide the paper towel into the labelled plastic bag, sealing well to create humidity. Seeds need air, so don’t squash it all out of the bag!

If you have more than one seed variety to test at the same time, gently roll up the paper towels into cylinder shapes and lay flat in a row. Then they can all share the same plastic bag. Remember to label each variety inside. You may want to colour code with a slip of paper.

Lay the sealed bag flat (or seed raiser) in a warm or sunny spot. For example, near your cooktop or a TV that gives off warmth; or a drying cupboard above a hot water heater.

Step 3: Check for Seed Germination

Keep moist for the number of days required for your seed variety to germinate. Spray extra water if needed and check every couple of days or so to see if any seeds have germinated. If some of the seeds start to germinate, you’ll know the rest is worth sowing too!

Some seed varieties take longer to germinate than others, so take that into account. Remember you may need patience for this project! While some seeds germinate in a couple of days, others take 21 days.

Check your seed packet for average days to germination. Mark this on the bag so you know what date to expect they should shoot by.

Check your seed packet for average days to germinate. Mark this on the bag so you know what date to expect they should shoot by.

How to Calculate Seed Viability

Now count the number of seeds out of 10 that germinate successfully. Then you can calculate the viability for the remainder. So, if 1/10 sprout, your seed only has 10% viability. It’s best to sow as soon as possible! If 9/10 germinate, 90% of the seeds are still very viable. In this case, you can keep in storage if you don’t need to sow now. This test will help with your decision-making.

Sharing Seeds for Mutual Benefit

What if you can’t sow soon or it’s not the right season? Don’t throw the seeds out! You can always donate to a local community garden, garden club or seed saving group. There are seed savers in every community. Ask them to grow on for you and save you some from their next crop. Think win-win! You’ll probably make some new gardening friends at the same time.

If none of your seed germinates, it might be best to start again with new season seeds and plant sooner.


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Do you have too many seeds? If so, why not share with a friend or gardening group. Splitting up seed packets saves money and allows several people to grow in different soils and conditions. So if yours fail, you have a backup! Free seeds are one of the benefits of being a member of a seed saving group.

How to Store Seeds Safely

To maintain the quality and life of your seeds, how you store them really matters! If your test results were poor, this may be a wakeup call to improve on your seed storage method.

“Every seed has the ability to provide you with enormous food value. They’re an investment in your future health so they deserve to be treated like royalty!” – Anne Gibson

Ideally, store seeds in a sealed air-tight container or glass jar in a dark, dry, cool spot. If you have room, a sealed box in your fridge is ideal. Tablet jars are also handy. I add a silica gel sachet to absorb moisture in each jar, but a few grains of dry rice will do the job too.

Temperature and light fluctuations during storage can impact life in the seeds. e.g. If you constantly open a cupboard or fridge door. Assess how you can improve your seed storage. Relocate your seeds if necessary, to more favourable consistent conditions.

If you follow these tips, you should be able to test your seed viability and store your seeds for long life and abundant harvests.

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