For the Garden or for the Birds: How to know if last year’s seeds are viable

Yesterday’s blizzard piled us with snow, and the plow trucks are back on the road.

Good thing you practiced your patience and held off on seeding the other day.  (Remember that sunny, 50º day just last week?  Me too.  It was glorious).  Just back inside from a morning ski, Edge reports that the new snow is glorious, too.

All this snow isn’t keeping us from preparing for spring.  We’re organizing our seeding calendar, setting up tables in the greenhouse, and clearing out old seeds from storage.

A friend recently asked me if she should plant seeds that she’s had hanging around for a few years.  I told her maybe.    Seed viability (the ability for a seed to germinate) depends on two main factors: storage conditions and age.

Storage Conditions

Having seed left over at the end of the growing season is inevitable.  If you plan on using that seed next season, proper storage conditions are key.  They’re also quite simple.

When you store your seeds, remember three things: Dry, Dark, Cool.

DRY: humidity is the enemy of seed storage.  Humidity is water in the air, and water causes seeds to germinate.  For long-term storage, keep humidity below 40%

DARK: keeping seeds in their original packaging is an easy way to block out light and remember what variety they are.  Don’t leave seeds out on the windowsill, or anywhere they might be exposed to direct light.

COOL: Most seeds germinate in soil temperatures of 60º and above.  Keeping them cool encourages longer life in storage.

Easy seed storage methods to increase seed viability:

Glass Jars: place seed packets in dry mason jars and seal tightly.  Keep jars either in the refrigerator or the freezer. (hint: if you’re concerned about moisture levels in the fridge, place a folded paper towel in the jar to draw moisture away from the seeds).

Plastic tubs: at Good Heart Farmstead, we have a lot  of seeds, which we store in our walk-in cooler.  To keep them organized, we label individual tubs by plant family and crop type:

  • Herbs
  • Flowers
  • Roots (beets, carrots, radishes, turnips)
  • Brassica (kale, kohlrabi, broccoli, cauliflower, cabbage, etc)
  • Cucurbit (squash, pumpkins, cucumbers)
  • Solanacea (tomatoes, peppers, eggplant)
  • Greens (salad mixes, asian, mustard, chard)

If you don’t have space in your fridge, freezer, or a cooler, some common places in your home that may be suitable for seed storage include: closet, pantry, or garage (just be sure to check the humidity!)

Seed Age

Most properly stored seeds remain viable for at least 3-4 years.  The exception is onion and leek seed, which you should purchase new (or save your own) every year.  Germination rates and dates are typically printed on seed packets, and the date lets you know the relative age of the seed.

If the date on your seed packet is within the last 2-3 years, and if you properly stored your seeds, then you should plant them!

If you’re concerned about low germination rates, do the paper towel test:

  • Place 10* seeds in a damp paper towel (*depending on how many seeds you have, you may increase this number to get a larger sample.)
  • Fold paper towel and place in a sealed plastic bag to maintain moisture
  • Label the bag with date, crop and variety name
  • Store bag in warm place (68-75º) out of direct sunlight
  • Check in 5 days, and count the number of sprouted seeds.

cucumber seedlings80-90% germination = GREAT!  Plant away!

60-70% germination = Good, but seed a bit heavier

50% and under = Give them to the birds (or the compost).  Low germination rates aren’t worth your precious time and soil.


Now it’s out to the snow for me!  Because winter won’t be around forever…right?

1 thought on “For the Garden or for the Birds: How to know if last year’s seeds are viable”

  1. Pingback: When You're Caught Between Winter and Spring, Do This - The Good Heart Life

Leave a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Scroll to Top