Don’t Do This: Germination Failure

I mentioned in my last post that I had to replant all the spring seeds in my germination station. That’s right, all my tomatoes, peppers, eggplant, squash, and melons. Four trays of them. Why? Because after two weeks, nothing except one solitary watermelon germinated (and then died). Nothing. Nada. Zilch. Zero percent germination? With new seeds? No way. Something had to be wrong. So I dug into a couple of the cells and found moldy seeds. Huh?

This is only my second year starting seeds indoors. So, being a newbie, I did a bunch of research to figure out why my seeds didn’t germinate.


One reason my seeds didn’t germinate is that the temperature inside my seed trays (with domes on) was probably too high. Tomato and pepper seeds will germinate well when the soil is 70 to 80 degrees Fahrenheit.Temperatures below 50 degrees or above 90 degrees are detrimental to germination.

I have germination mats under my seed trays, which I turn on during the day (to mimic the sun’s warmth on the soil). This bottom warmth helps with good root development. I also had my new grow lights set up at the right height above the seed trays – for seedlings and plants, that is. I wasn’t thinking about the fact that I have domes on my seed trays to keep the humidity high inside the trays. With the lights so close to the plastic domes, the temperature inside the trays was intensified. (Think green house.) When I placed a thermometer probe inside the domes, it was almost 100 degrees! Uh…not good.

So, I raised the grow lights another six inches above the trays so that I can barely feel the heat on the back of my hand when I place it on top of the domes. Once the domes are removed from the trays (once germination has begun), then I can lower the lights closer to the plants.

Germination station with lights lifted higher above the domes

Germination station with lights lifted higher above the domes

That was problem number one. Purely my bad. I’ll take only partial credit for messing up the next issue.


There is a proper soil for seed germination, and it isn’t actually a soil at all. In fact, it should contain no soil. Here’s where I made my mistake.

I couldn’t remember what brand of germination mix I used last year. (I neglected to write it down in my garden journal – oops!) So I went off to Lowe’s, couldn’t find anything organic, and decided to try the Miracle Gro Seed Starting Mix. (Don’t hit me…I’m already beating myself up.)

The package actually said “Seed Starting” in big letters. Yet, when I was filling the cells in my trays, I was thinking, “This isn’t like what I used last year. This seems more like potting soil.” Here’s what it looks like:

Miracle Gro Seed Starting Mix

Miracle Gro Seed Starting Mix

For all you veterans out there, it IS potting soil! I was misled by the bag, yes, but I should’ve listened to my gut instinct. Instead, I planted my seeds in it anyway.

Soil is too “thick” for tender seeds like tomatoes and peppers. It’s not very porous, doesn’t contain enough oxygen, and retains too much moisture – all bad for germinating tiny seeds. This explains why my seeds were getting moldy. They were in the wrong mixture. (NOTE: Seeds that can be planted directly outside do fine in soil, but seeds that need to be started indoors need a special medium to grow in.)

Well, now I was two weeks into the germinating season with no seedlings. I placed a rush order online for Gardener’s Supply Germinating Mix and paid for priority shipping. I got it in three days. When I opened the bag, I knew I had the right stuff. It looked just like the mixture I used last year.

Proper seed germinating mix should be a combination of sphagnum peat moss (or coconut coir) and vermiculite and/or perlite. It will be fluffy and be able to hold moisture while letting the seeds breath. Look at the difference:

Germination mix by Gardener's Supply

Germination mix by Gardener’s Supply

I dumped the cells with the potting mix and dead seeds and started with new cell pots. When I filled them with the germination mix, the mixture felt spongy. Ah, just right!

This mixture is perfect for germinating seeds, but it will not feed your seedlings. Seedlings can feed themselves until they get their first true leaves, then you’ll need to feed them.

With all the research I did online, I found that you can add a little food to the germination mixture without hindering the seed’s germination. I’m hoping this will help my seedlings get off to a better start before I start feeding them. (Based on testimonies I read, this should be so. I’ll let you know.)

I made several small batches of this mixture. Each batch filled eight six-cell pots.


  • 9 cups germination mix (I used Gardener’s Supply mix, but you can use Jiffy’s Natural & Organic germination mix, too.)
  • 1 cup worm castings (keep the vermicompost to no more than 10% of the mixture)
  • 1/4 cup Azomite (rock dust – for micro nutrients)
My germination mixture

My germination mixture

I mixed the three ingredients very well, then filled my cells. When the trays were full, I watered them so the mixture was very moist. Then I added the seeds (pushing the large squash and melon seeds into the mixture but leaving the small tomato, pepper, and eggplant seeds on top). Once the seeds were in place, I sprinkled the plain germination mix (without my additives) on top of the seeds – so they’d be “buried” about 1/4 of an inch. Finally, I misted the trays so the new mix got damp, put on the domes, and put them in my grow room.

That was three days ago. I hope to see my first seedling soon. According to last year’s garden journal, I had my first seedlings in five days.

I was quite upset about losing 288 seeds and two weeks of precious seedling growing time. Thankfully, I had lots more seeds, and we do have a long growing season here so transplanting two weeks after the last frost isn’t a total disaster. Trials and errors are part of gardening.

Please share with me if this post was helpful to you, keeping you from making the same mistakes; if you can learn from me, then my error wasn’t so bad. (Then again, I now have to wait an extra two weeks before tasting my first sun-ripened tomato. To this Italian gardener, that’s torture! 😉 )

May your seedlings be healthy!

UPDATE: To learn a great way I’ve found to germinate pepper and tomato seeds, click here.


One comment on “Don’t Do This: Germination Failure

  1. Pingback: Germination Process: Step One | Harvest Daylily

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