How Long do Seeds Last?

This time of the year I see lots of seed starting tricks.

One seed starting tip is pre-germinating your seeds before planting them into pots.

Another is pre-germinating your old seeds so you’re not wasting them.

Now I’m a big fan of not wasting anything, however, I’m also a gardener that focuses on creating productive gardens.

However, people seem to forget that just like animals, plants have their own survival of the fittest.

How Long Seeds Last and Plant Vigor

A seed has the ability to germinate and create life, but as it ages, it loses it’s ability to grow into a healthy ‘normal’ plant. 

A healthy seed can produce normal seedlings under less than optimum or adverse growing conditions. Old seed may germinate and that may create excitement that you don’t have to buy fresh seeds this year, but I’m here to let you know that you need to make the decision based on observation of that seedling and how fast or well it grows.

The Association of Official Seed Analysts (AOSA) states: 

“Seed vigor comprises of those seed properties which determine the potential for rapid, uniform emergence and development of normal seedlings under a wide range of field conditions.”

This image below is from the Oregon Seed Laboratory that shows the difference in seedling vigor.

Plant Vigor Test

This season when using my seed inventory spreadsheet, I noticed I had two varieties of eggplant (Listada De Gandia  and Ping Tung) that were 3 years old. I didn’t want to waste the seeds so I thought I’d germinate them and see what happens, however as a back up, I also purchased new eggplant seeds (Rosita).

Below you can see the vigor comparison. These seeds were sown on the same day at the same time, and they all germinated. Within a few weeks the difference in growth (or lack thereof) is staggering!

Old Seeds

New Seeds

Should you use the old seeds then?

That depends. Different crop varieties will have varied plant vigor, and sometimes hybrid versus OP makes a difference. I’ve been trying to grow ‘Arroz con Pollo’ peppers for a couple of seasons now without much success, but I recently found out that that specific variety of pepper grows way slower than most pepper varieties. After finding this info out I will try for one more season.

However, based from the above photos and depending on how the growth goes for the next month, I may not transplant those old seedlings into the garden at all.

Those slow growing plants might not bring any harvests which means wasting valuable growing space & time.

Certain people also claim that different seed companies also have better seed viability than others and if you didn’t store your seeds properly that greatly reduces seed vigor.

A Growing Garden has this great infographic on seed viability

Conclusion

You can definitely use old seeds if they were stored properly and they show no signs of poor vigor.

If you germinate your old seeds but the growth is poor and many of the seedlings don’t appear to look ‘normal’ then it’s a better idea to buy fresh seed instead.