Older Seeds-how to test for viability


If you have gone through your seeds and find packets that are over 3 years old, you may want to test them for viability. Are they still good enough to plant again? Many seeds are good for 2-3 years and some much longer if they didn’t get wet or damaged. I grew the state record for giant green squash (345 lbs) from a seed that was 8 years old. I was amazed. Read about the giant green squashes here; https://giantveggiegardener.com/2011/10/04/greenies-battle-it-out-for-who-will-go-to-the-weigh-off. So sometimes older seeds are fine too. Here are some things you can do with older seeds.

  1. First,  if they are over 3 years old I may toss them in the ground later in spring (especially flower seeds) to see if they germinate or
  2. I may test the seed packet (look at the date on the package) to see if they are still viable. Three years or older? Test them. To test them, take 10 seeds and soak them in water for a few hours to overnight and then put them in a damp paper towel and put them in a Ziploc bag and on a shady, warm windowsill or on top of your refrigerator (not a sunny place, you don’t wanna fry the seeds). Then in a few days check them to see how many have germinated.
  3. I use this chart  “Germination tables from Heirloom Seeds – Know when to plant all your vegetables.” to see how long it should take to germinate a particular seed under ideal conditions.  If none have germinated, keep checking them. After a few days, you’ll see some of them have germinated. So if 8 out of the 10 germinated, you have a 80% germination rate. If 5 out of the 1o seeds germinated, then you have a 50% germination rate, if only 2 have germinated than you have a 20% germination rate and so on.  I would probably toss those. This chart is also great to have when we are actually ready to start seeds inside under lights or directly outside (later) to see what is the optimum soil temperature is for each seed and how long it will take to germinate. I will post later on that when starting seeds inside or outside. This is just to test for seed viability right now.

Seed Starting Class

tomatoes 4_17_11

Today I taught a Seed Starting Class at the Rail Yard classroom here in Santa Fe. We ran out of the handouts because so many people showed up. It was a great class with lots of ideas shared by both me and the participants. I promised to put the all the handouts on my blog for those of you who didn’t get them.







ALSO! Here are some of my posts that might be helpful on things we talked about today:

BUILDING A LIGHT BOX –   https://giantveggiegardener.com/category/gardening-tips/building-a-light-box-gardening-tips/

SEED STARTING TIPS –  https://giantveggiegardener.com/category/gardening-tips/starting-seeds-tips/

GOPHERS PROBLEMS/TRAPS –  https://giantveggiegardener.com/2011/01/20/gopher-problems/

DETERRING SQUIRRELS –  https://giantveggiegardener.com/2011/08/16/deterring-squirrels-from-eating-your-garden/

TOMATO SEEDS PLANTING INSIDE – https://giantveggiegardener.com/2011/03/22/tomato-seeds-planted-inside-march-21/

Finally, there is a ton of information on this site. All you have to do is look at the right hand column and go down to ‘Garden Topics’ and go to the subject that interests you. That way you will only get my posts on that subject and you don’t have to scroll through 4 years of posts.

Seed Heating Mats for Starting Seeds Indoors

I did a little experiment. I started my lettuce bowl, putting seeds on the ‘bowl’ and lightly covering with sand. I didn’t have enough room to put the whole bowl on my seed heating mat (I’ve ordered another one) so I put half ON my mat and half OFF the mat as in the picture. The heat comes from the bottom. The temperature of half ON the heat mat was 77°F and the half OFF the mat was much cooler at  70°F. The half on the mat germinated in 3 days while the half off the mat had only a few seeds germinate. Amazing how the temperature affects the germination rate. Lesson here? If you plan to start seeds indoors, get a seed heating mat. Next: Review of my Seed Starting Class last Saturday.