Seed Starting Problems?

Even when you know a good deal about propagating from seed, you can still find yourself puzzled over why you’re having problems getting your veggie garden seedlings started. Last year my germination troubleshooting on what was wrong with my trays of tomatoes and peppers led me to suspect it was the potting mix used. All the cells that nothing sprouted in I had a terrible time keeping moist – even under a humidity dome! I decided there was something wrong with the spot in the bag that they were filled with, the coir in a third of them simply refused to retain any moisture, and everything was on a capillary mat.

So this year I switched mixes again. I had less germination problems in Miracle Gro potting mix, but also tons of mold, and not the most aggressive root systems. So I decided I needed to avoid so much peat most and go with a product that had more coir in it. There was also a second reason for this switch, I wanted to see if I had better root development as coir has neutral pH that makes plants happier than the higher pH of peat moss. The plants that sprouted last year did indeed have great root mass. They made the plants purchased from the garden center to fill in for what didn’t sprout look kind of sad both above and below the soil line.

I have to tell you that it’s definitely not the medium in the cells. I had tomatoes popping in 3 days flat! The first pepper came up in only 4 days – a jalapeno, at that. Hot peppers usually don’t begin appearing for a couple weeks – they’re very slow to sprout, and to grow too. But I know that part of it is the moisture holding makeup of my new soilless mix, but that’s not the only reason for this fast germination. The season here is super short, so having the biggest plants possible from a very small growing space is the goal, and the earlier I get them sprouting, the more developed they will be when planting time finally arrives.

One other thing I did differently this year was planted my seed very shallow. Covering them with only a skiff of mix over the seed has a good deal to do with it. Just enough to cover it completely, because planting depth is part of why some seeds take longer to germinate than others. Seed pack planting depths are calculated for starting them outside in the garden. Inside a humidity dome with bottom watering via a capillary mat gives your seed a lot more moisture, and it’s consistent moisture that activates life in a seed. Not waterlogged, that will suffocate your sprouts and seedlings.

Still, my tomato forest is thin this year, as you can see in that image above. Only 20 of the cells in my 32 count tray sprouted, and they were all out of the soil in 11 days. The mixed tray of bell peppers and jalapenos did better with only 7 empty cells, and in the past I’ve had more problems starting peppers than tomatoes!

They aren’t too cold. These tropical plants love warmth, and they’re on a heat mat, which is one more reason that they were jumping out of the mix in record time. So what is wrong? Some of it could be due to most of these tomato seeds being left over from last year, but they’re properly stored in an air-tight container in a dark cupboard. It’s the same way I’ve stored seeds for many years. There is the possibility that the seed just isn’t the greatest, and the place the pepper seeds came from last year does not have the best reputation for great germinating seed. So I purchased new pepper seed from Baker Creek this season, and still I’ve got empty cells. One or two is to be expected, but not 1/4 to 1/2 of the tray!

It’s not that the seeds in those cells are just slow. Nothing new has happened in the tomato tray for 11 days besides the second tomatillo finally arising. I reseeded the empty cells last weekend, because I’m not growing the stuff they sell at the flower place here if I can avoid it. All these new hybrids lack a lot of flavor, which makes for some bland home preserved salsa.

So what is the problem? You will rarely have 100% germination from any seed. Plant more than you need to insure you have enough plants in the end. Seeds are not expensive, but growing your own garden plants from seed is a time sensitive project. Instead of sowing one seed per cell – put in 2-3 seeds. At least one out of 3 should germinate. If you’ve got 2-3 sprouts, remove all but the most robust one. And, if you’ve got the room to pot up a few of your extras, loosen the potting mix around them deeply, but gently. Then you can remove the extra seedling and grow it on. It will save you from having plants of different stages of maturity, or having to go buy more from the local garden center in the end.

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  • Bill Graham says:

    Hi Tammy,
    I wanted to ask you what size shelf you are germinating your plug trays under? I see the foil sides and fluorescent lights and it looks a lot like the four foot racks I am using. I make a 24″ x 45″ od shallow flood tray for easier bottom watering and can get you one from the MI warehouse if you can use it.
    Keep us the good blogging!

    • Tammy says:

      Hey Bill,

      How are you? Nice to see you’ve popped in.

      I’d love a flood tray, and yours would fit. The homemade rack has oversize shelves about 52″ x 28″. Tomatoes are thirsty critters once they get going.


Tammy Clayton

Contributing Writer at Garden Culture Magazine

Tammy has been immersed in the world of plants and growing since her first job as an assistant weeder at the tender age of 8. Heavily influenced by a former life as a landscape designer and nursery owner, she swears good looking plants follow her home.