Do you have old seeds from last year and wonder if they are still good? Try this simple seed germination test to find out if they are viable. See how to test your old seeds so you don’t waste time and effort sowing seeds that won’t grow.
As I eagerly wait for spring, and the stores begin to roll out their spring gardening and seed starting supplies, I find myself drawn to the seed displays. Before I know it, I usually have a few packages in my hands to purchase. Sometimes I end up with duplicate packages of seeds.
How Long Will Seeds Last?
Luckily, depending on how the seeds are stored, most seeds can last several seasons or more. Seeds do lose potency over time and will have a decreased germination rate the older they are. Some seeds like onions and parsnips are not likely to sprout a second year. Even if they do germinate, they may not have the vigor to produce healthy plants like when they were new. When in doubt, it is best to purchase fresh seeds rather than jeopardize your crop’s success.
The seed viability list below will give you a general idea how long vegetable seeds will last:
- 1 Year: Leeks, onions, parsnips, and scallions
- 2-3 Years: Arugula, beans, carrots, celeriac, celery, corn, eggplant, lettuce, okra, peas, peppers, and spinach
- 3-4 Years: Artichokes, beets, broccoli, Brussels sprouts, cabbage, cauliflower, collards, kale, kohlrabi, mustard, pumpkin, radish, rutabagas, summer squash, Swiss chard, and winter squash
- 5-6 Years: Cucumbers, melons, tomatoes, turnips, and watermelons
Use this chart just as a guideline though. I have experienced onion seeds still sprouting after three years and lettuce seeds only lasting over one year. It all depends on the quality of seeds and how they are stored.
How to Store Seeds
Seeds will last longer if they are stored in a cool, dry, and dark location. Ideal temperatures are between 40 and 50˚F. I place my seeds in zipper bags and store them in plastic shoe box totes in a dim corner of the basement away from the furnace. If rodents are a problem, you can store seed packets in sealed glass jars.
How to Do a Seed Germination Test
Before you throw those old seed packages away, test them to see if they are still viable using this simple germination test. Follow these steps to test your seeds to see if they will sprout:
Step 1: Gather Your Supplies
You will need plain paper towels cut in half, plastic zipper bags, a bowl of water, a marking pen, and seeds to test.
Step 2: Introduce the Seeds to Moisture
- Moisten a paper towel by dipping it into the bowl of water and squeezing out the excess moisture. The paper towel should be damp, but not dripping wet.
- Spread the damp paper towel out on a clean surface and fold in half.
- Select at least ten seeds from the package you are testing.
- Spread the seeds out on one-half of the towel, so they are not touching.
Step 3: Package Up the Seeds
- Fold the damp paper towel in half sandwiching the seeds between the two layers. Press down gently to make sure seeds come in contact with the moist paper towel.
- Place the paper towel and seeds in a zipper bag and seal it to keep it from drying out.
- Mark the bag with the date and variety of seed. Place the zipper bag in a warm place away from direct sunlight.
- Every three days, check to see if the seeds have sprouted. Re-moisten the paper towel if it dries out.
Step 4: Assess the Seed Germination Percentage
After the predicted germination period, count the seeds that successfully sprouted and calculate the percentage that germinated out of the total tested. Example: if 9 out of 10 seeds sprout, you have 90% germination rate.
If the germination is greater than five sprouted seeds (50% percent) I will use the seeds knowing that I will have to pre-sprout the seeds or sow a little heavier to make up for the lower germination rate.
I take the test further by planting the seeds that germinate so I can observe the seedlings as they grow. If the plants are slow to grow or not healthy looking, I will throw them out and buy a fresh package. I want my seedlings to have the best shot at success.
After this simple, quick test, you will know if you need to buy new seed because the leftover seed will not sprout, or if you need to plant heavier to make up for the reduced viability.
Now that you have tested your seeds, you are ready to make a seed list and plan your garden.
You May Also Like:
- How to Organize Seeds and Make a Seed List
- How to Make a Seed Starting Schedule
- 10 Steps to Starting Seedlings Indoors
Good planning is key to a successful vegetable garden
Whether you are new to growing your own food or have been growing a vegetable garden for years, you will benefit from some planning each year. You will find everything you need to organize and plan your vegetable garden in my PDF eBook, Grow a Good Life Guide to Planning Your Vegetable Garden.