It’s a few weeks before spring, and gardeners everywhere are starting baby plants from seed. Germinating seeds isn’t usually a difficult process, and for most veggies the process is quite simple.
If you’ve never started your plants from seed, then check out our free seed starting guide.
But what do you do if your seeds don’t germinate?
When seeds don’t sprout, you should always take time to evaluate what happened. So I thought it would be helpful to talk about the most common reasons you might have seed germination problems.
Some years our germination is a little patchy, and occasionally whole rows of seedlings will not germinate. It is important to keep up with our germination rate to evaluate our technique and seed health.
For us, a minimum acceptable germination rate is when at least 80% of our seeds sprout. But ideally, 100% of our seeds come up, so anything less than 80 or even 90% germination rate, and we start looking at what went wrong.
Learn the 5 fatal mistakes for germinating seeds
When vegetable seeds are not germinating, there are a few common problems that you should look for.
1. You used old 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 that it was an old seed or not properly 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.
For new seeds or seeds you saved last year:
- When you saved seed, did you put them away without letting them dry completely? This can cause seeds to rot or mold.
- Were they exposed to extreme temperatures during storage? For example, if you left seed packs in your car over the summer. High temperatures over 90 can kill the plant inside the seed.
- Was the parent plant healthy? Seeds can harbor infection from the parent plant that may prevent sprouting, however, this is not usually the case.
2. You didn’t use new or sterilized 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 a seed sprouts, but then rots at its base and falls over.
This is called damping off and is caused by a funal infection in your soil. A hydrogen peroxide or colloidal silver solution can help treat fungal disease on your tender plants.
3. Your technique is not right
- If you started seeds in any mix that includes non-sterilized soil from the yard, your seeds may have been affected by disease organisms in the soil.
In order to use garden soil for starting seeds, you should sift it carefully to remove sticks and clumps. Then bake it on a cookie sheet in the oven at 180 degrees for 30 minutes. That should kill most weeds and pathogens.
You’re better off using a seed starting mix. Seed starting mix is usually a soiless mixture that has a finer grain and is free of clumps, sticks, and pathogens.
- Did you plant your seeds too deep?
Planting your seeds too deep can cause problems with sprouting. You should also avoid pressing down on top of your seeds after you plant them. If the soil in your container is too compacted, the seeds cannot sprout or form healthy roots.
4. You didn’t provide the correct temperature
The temperature of your soil is of utmost importance in getting a good seed germination.
- Temperatures that are too high or too low can cause problems germinating seeds.
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.
- Did you leave the heat mat too high or too low?
Even when using seed starting heat mats, accidents happen. If you forget to put the temperature probe into the seed tray, the heat mat can overheat and cook the seeds.
Sometimes heat mats get accidentally turn off, or you forget to plug it in.
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. You watered incorrectly
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 sprout, 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.
- Tender seedling 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.
What other problems have you had germinating seeds?
If you’ve had troubles germinating seeds and this article didn’t answer your question, leave me a comment below. I’m happy to help you work out what’s going on.