|
 Unfortunately,
as seeds get older, their germination rate decreases. Fortunately,
there is an easy way to test your seeds to see if planting them will
be worthwhile.
How long do seeds last?
Many seeds are capable of lasting for several years if stored
properly.
• 4 to 5 Years: Basil, broccoli, cabbage, cauliflower, cosmos,
cucumber, eggplant, lettuce, nasturtium, oregano, pumpkin, radish,
snapdragon, squash, sunflower, tomato, watermelon, and zinnia
• 1 to 2 Years: Bean, carrot, celosia, daisy, peas, poppy, okra, and
pepper seeds can last for around three years. While seeds of aster,
coneflower, fennel, sage, onion, pansy parsnip, and sweet corn.
Checking seed germination
Download the PDF at
https://
extension.illinois.edu/sites/default/
files/infosheet_seed_viability.pdf
Testing seed germination is relatively simple and only requires a
paper towel, a sealable plastic bag or container, water, a permanent
marker, and the seed you want to test.
1. Moisten the paper towel and lay it flat
2. Place 10 (can be more) seeds on the paper towel and fold the
towel over the seeds.
3. Place the paper towel in the plastic bag or container and seal
it. This will help keep the paper towel from drying out. Label the
container with the plant name and the date planted.
4. Place the bag in a warm area, like on top of a refrigerator (just
don't forget about it). Warmer temperatures (around 70°F) will help
speed up the germination process.
5. Every few days, check the seeds to see if they have germinated.
Seed packets will often list how many days it will take for seeds to
germinate. You can also use this information to help you determine
when to start checking seeds. Many seeds will germinate within 7 to
10 days.
Once seeds have germinated, you can determine your
percent germination; most people do ten seeds to make this
calculation easy. If all of your seeds germinate, you can plant
normally. If 70% to 90% of the seeds germinate, you can still use
the seed, but you may want to sow a little heavier than normal. If
fewer than 50% to 60% germinate, it is probably best to buy new
seeds. While most vegetables don’t require
stratification, some flowers do. Plants like milkweed, purple
coneflower, and black-eyed Susan require cold, moist stratification.
https://extension.illinois.
edu/blogs/good-growing/2022-01-27-seed-stratification-what-seeds-require-cold-treatment
[to top of second column] |
If you have instances where you get no germination,
make sure the plants you are testing don’t need some sort of
stratification.
When testing seeds, place ten seeds on a moistened paper towel
(top). Check seeds periodically to see if they have begun to
germinate. These rice seeds have begun germinating (arrows) after
five days (bottom). Click on image to enlarge.
Properly storing seeds
If you have leftover seeds or are planning on saving seeds for next
year, make sure you store them properly, so they remain viable as
long as possible. Seeds should be kept cool and dry location,
ideally below 45°F. Placing seeds in a sealed jar or bag in a
refrigerator is a good option.
As a general rule of thumb, the sum of the temperature (°F) and
percent relative humidity (RH) should be less than 100. So, storing
seeds at 60°F at 30% RH would be good conditions. While storing
seeds at 50°F and 60% RH would lead to reduced seed longevity.
Good Growing Tip of the Week: Seed germination and
viability are often used interchangeably, but they mean different
things. Germination is the ability of a seed to sprout. Viability is
the seed’s ability to produce a vigorous seedling. Viability often
declines before germination, so it’s possible for old seeds to
germinate but produce weak seedlings.
[Author: Ken Johnson, Horticulture
Educator, University of Illinois Extension] |
