A low seed germination rate is always something that needs to be evaluated. Some years our germination is a little patchy, and occasionally whole rows of seedlings will not germinate. For us, it is important to keep up with our germination rate to evaluate our technique and seed varieties.
If you’re wondering how to calculate your germination rate, divide the number of seedlings you have by the number of seeds you planted. We expect at least 80% of our seeds to germinate, but 100% is the goal. Anything less than 80 or even 90%, and we start looking at what went wrong.
So what should you do if your seed germination isn’t up to par?
Go through these steps to figure out what went wrong:
1. Check your seeds
The first thing to consider is whether the seeds were viable in the first place. If your seeds have not sprouted within the appropriate number days (this will depend on your seeds), then you may want to consider using a pen or pencil to gently dig around in your soil and find the seed.
If you don’t find the seed, think back. Did you forget to put the seeds into the mix? Don’t laugh! It could happen!
If you find the seed, take a good look at it. You may see that it looks just the way it did when you put it in the soil. In this case, the cause for a low germination rate might be age or how the seed was stored.
If you have some old seeds and are unsure of whether your seeds were viable, you can always sprout a couple of them in a wet paper towel to check prior to planting.
I am not going to go over seed saving in this post, but the biggest mistake you can make is to put them away without letting them dry, inviting rot and mold.
For most vegetable seeds, high temps can also kill the baby plant inside the seed. So don’t forget about them and leave them in your car over the summer.
Finally, seeds can harbor infection from the parent plant that may prevent sprouting, however, this is not usually the case.
2. Think about your containers
Disease issues can be a factor in seed germination. Think back to last year and whether you had any disease issues with your seedlings.
Most plastic containers can be reused for several years, but they need to be sanitized. We clean ours by submersing them in bleach water at the beginning of the season.
If you are looking for a bleach alternative, try the environmentally friendly bleach alternatives that use hydrogen peroxide as their active ingredient.
Fungal and mold infections are the most common infection from dirty containers. If infection occurs you will notice a fuzzy growth on the top of the planting medium.
You may also see that the seedling rots at its base or dampen off. A hydrogen peroxide or colloidal silver solution can help treat fungal disease on your tender plants.
3. Consider your growing medium
Seed starting mix is really the best option for getting good germination of seeds. There are potentially many weed seeds and diseases in garden soil. One of the benefits of starting your seeds indoors is to avoid having to deal with weeds and disease.
However, if you really need to use garden soil, it should be sifted to remove sticks and clumps then baked in the oven at 180 degrees for 30 minutes. That should kill most weeds and pathogens.
4. Look at the temperature
The temperature of your seed trays is of utmost importance in getting a good germination rate.
Given all else is equal, even tray germination requires even temperatures. If temperatures plunge at night, or peak over 100 for a prolonged period, seeds will either remain dormant or die.
An alternative to the heat mat is to put them in a sunny south facing window or on top of the refrigerator. You can also use grow lights to provide heat above, and I have even seen people use rope lights to generate warmth.
5. Don’t forget about watering
Did they get plenty of but not too much water? Seeds need to be moderately moist to sprout.
Seed germination is highly dependent on watering. Too dry and they won’t get the message to pop, too wet and they will rot in the dirt. Very young seedlings are even more tender. Seedlings do best in what we call the “Goldilocks zone.”
You know Goldilocks. She likes her porridge not too hot and not too cold, but juuust right.
These tender babies can’t tolerate drying out. While young, even a short dry period can mean death after the first wilt.
On the other hand, their tender roots will be the first victim of conditions being too wet. They can’t get the oxygen they need to carry about their business, and it will stunt or kill the seedling.
Hopefully, you don’t have to worry about a low seed germination rate, but if you do, just know that you are not alone.
We all make mistakes and some seeds are more difficult to grow than others. I hope this guide helped you prevent or learn what went wrong and how you can fix it.