Reinvigorating Old Seed

Some very old (yet valuable) cucumber seed

A recent issue with a cluster of old seed exhibiting poor germination led me to observe that, like Bill Gates stated, “Success is a lousy teacher”. In order for a gardener to improve his skills, he must be faced with failure and sometimes a lot of failure, though humbling, can be a great thing. Every failure that is recognized is a stepping stone on the road to success. That being said, just because I have identified 45 obstacles to growing tomatoes in my climate does not mean that I am not ignorant to the other 55 reasons why I cannot. The following information on reinvigorating old cucumber (or melon) seed is based solely on my experience with some very old melon seed. As my posts are not permanent, should anyone have any other helpful hints I would be happy to try them out and add them to this post.

The key to planting any seed is to first determine its percentage of germination. In an ideal world the germination of seed would not degrade over time, but - for various reasons - it does. The reason why a gardener would want to test germination before planting their seed is that germination testing enables the gardener to determine how dense to plant the seed. Seed with high germination rates requires less planting and more space between sowing while seed with very poor germination can require very dense sowing, resulting in the gardener seeing only 1% of the seed strong enough to become a seedling. My approach to germination testing utilizes a snack Ziploc bag and a paper towel. Once the seeds have germinated, I can then plant them where I want to grow. The only problem with planting the seeds I germinate is if I need to test germination of summer vegetable varieties in the winter.

Should you be in the position in which you have cucumber or melon seeds that do not germinate well, here are a few things you can do to. The majority of this information can be applied to working with other vegetable seeds.

1. Pre-sprout seeds as if you wanted to test germination.

This means placing the seeds in a controlled environment that is warm and moist. I like putting my whole “cucumber seeds in a moist paper towel in a snack-sized Ziploc bag” in my water heater closet. Controlling the environment helps ensure that each seed that can sprout is given every opportunity to do so.

2. Make sure that the sprouting medium (paper towel) is not too wet or too dry.

If the whole paper towel does not appear wet the seeds will not soak up enough water to sprout. Conversely, if I do not press out the excess water from the paper towel after moistening it then the majority of the seeds will most likely rot.

3. Remove anything that could rot or mold from the seed coating.

Even after properly fermenting cucumber seeds, seed growers sometimes do not clean all the old bits of fruit from the seed. I tend not to question why some companies leave miniscule bits of fruit on the seed, as the quality of a supplier’s seed is seldom related to the “stuff” left on the seed coating.

Dirty Seeds can mold, which can lead to poor spouting

Now the fleshy material is gone the seeds are ready to be sprouted.

4. Frequently check how the seeds are doing.

Once every day or two I check seeds that I am trying to sprout. This helps to check on possible problems as they arise.

 By diligent checking you may notice seeds sprouting (left) vs. nonviable seeds (right)

5. Remove all decaying seed.

As soon as I see a seed decaying I remove it. Seeds that are rotting will either drastically change color or will bloat up like a plump man who has outgrown his jacket. In this case, the plump inner seed portion has taken on water, which will decay the inside of the seed. If plump unviable seeds are left in the sprouting medium, the surface of the fleshy portion will decay until the fluids will pop out, spilling rotten sticky fluids onto the rest of the seed.

Notice the seed nearly popping out of its coat - like a plump man in a small coat

Another example of a nonviable seed that could pop open to rot the medium

6. Change the medium as often as necessary.

Should you choose a medium that is cheap and easy (such as paper towels) you can just throw it into the compost pile if it begins to produce a strange odor or change color. Changing the medium can help a few of the seeds that have not germinated yet to complete the sprouting process.

This bad example is for teaching purposes only! (=

If you forget to change your sprouting materials your seed will likely rot

7. Add a little bit of nitrogen-rich water-soluble fertilizer.

Sometimes a trace amount of nitrogen-rich fertilizer (such as Miracle Grow™) added to the sprouting area will help “wake up” some of the otherwise dormant old seeds. This does not always work and is not recommended for germination testing, but I have had a lot of success with adding a very miniscule amount of this kind of fertilizer to very old seed that needed some added help.

An ordinary water-soluble fertilizer (I normally never use this kind of thing)

I put just a very small pinch in (just a little more than on my finger tips)

8. For very old seed: Keep them in the controlled environment as long as possible.

Waiting until the seed coat is almost off is not necessary for vigorous seed, but with seed that is old and weak, ensuring that the seed is almost in seedling stage is highly important to ensuring that you can save this vegetable variety for the future.

Notice the seeds that have almost pushed off their seed coating (circled in blue).

9. Feed your seeds in a low concentration sucrose medium

Between when the seeds sprout and when they begin pushing off the seed coat, it is possible to feed them with a low concentration of sucrose in agar as mentioned in my last post.

10. Wait, wait, wait…

Seeds with low viability take a long time. Newly harvested seeds can sometimes fully sprout in under 12 hours while old seed can take over 20 days. Be patient. If the seed you are trying to grow was good but is now too old it may yet sprout.

Skilled gardeners store their most valuable seed carefully. Even if a gardener has thousands of seeds of a specific variety, storing a seed variety in poor condition can result in loss of the majority of the population. Though knowing how to bring old seed back to life is important, being able to avoid “babying” seed by properly harvesting, preparing and storing seed is much less work. By posting about my learning experience I hope each of us can better apply the words of Eleanor Roosevelt to our own gardening as she said, “Learn from the mistakes of others. You can’t live long enough to make them all yourself.”