Bad, Bad Soil: Why I Will Never Mix My Own Seed Starting Soil Again

Do you want to know what I was doing at 11:00PM last night, when I should have been snuggled in a warm bed next to an equally warm husband? I was repotting tomato plants. *sheesh* The things I do for my garden.

Things have not been going well with my first batch of baby tomatoes. They went from rebellious teen plants to deathly ill in just about two heartbeats.

At first, I thought their issues stemmed from a phosphorus deficiency. Added some more bone meal and a little more heat and… well, the purple went away and the yellow stayed. They plants got paler and paler, till the yellow became more akin to white than anything else.

I tried more water, less water, fertilizer and mojo bags (I didn’t think it would help, but I didn’t think it would hurt either), all to no avail. The plants were dying.

Bad SoilThe really baffling thing is that a batch of seeds I planted 3 weeks later is literally 10 times the size of these. They both got the same light, same watering regimen, same fertilizer applied. The only difference between the two is when the soil was mixed.

With the first batch, I did something terribly wrong when I mixed the soil, though what it was, I could not tell you. I thought I would be the uber-cool gardener and mix my own seed starting soil. It only contains Vermiculite, Perlite and Sphagnum moss. I tossed in a bit of bone meal for added phosphorous. How hard can it be, I had thought. Pretty hard, I guess.

When I repotted the little dears last night, I found that they had developed almost no root system. I am suspecting a nitrogen deficiency, but if that were the case, the fertilizer would have fixed the problem.

Beyond the fact that I have a dozen or so tomato seedlings that I am hoping make it through the week and recover some color, I also saved absolutely no money on making my own soilless mix. I only needed the little bags of vermiculite, perlite and sphagnum moss and they are not cheap. I would have been better off just buying a bag of the pre-mix soilless mix and being done with it. At least then I might have healthy tomato plants (you know, if it wasn’t for the fact that I was growing them in the first place).

So that’s it. I am swearing off seed starting soil making for the rest of my days. I’ll buy it by the bag from someone else. I am bad enough at starting seeds without having to worry about what the dirt is going to do to them.

2 thoughts on “Bad, Bad Soil: Why I Will Never Mix My Own Seed Starting Soil Again
  1. Sage on

    Maybe the problem was the lack of dirt?

    I know that ‘soil-less’ planting is becoming a fad… but to me, it makes sense that plants that grow naturally in the dirt just might want some dirt.

    I would recommend that whatever mix you use… add about 25% native soil to the mix. (Native soil being whatever soil you plan on putting the plant in once the seedling grows). This can help reduce shock when the seedling is transplanted later as the little fellow at least has an idea of the dirt to come before he’s placed in his new garden home.

    For my tomato seedlings… I use:

    + native soil … give the seedling a taste of the future

    + used coffee grounds … tomatos like the added acidity & it lends to good drainage

    + crushed egg shells … tomatos seem to like calcium

    + just a little bit of moss

    + oak leaf compost … no preference, it just happens to be found in natural abundance on my property

    If you have pest concerns in your soil… bake the batch for your seedlings to sterilize it. I put mine in casserole dishes in the oven at 400 degrees till I’m sure it’s cooked all the way through. (makes the house smell very unusual… but it works.

    My seedlings and tomatos do VERY well. I don’t think there is a magic formula. Just think about what a baby ‘mato needs and try to fill those needs. Something a little acidic if your native soil is too alkaline or nuetral. Something to give good drainage. Something to help retain a little moisture. Something to give nourishment. (Other then the use of compost and eggshells… I don’t fertilize until my seedlings are a few inches tall. Too much nitrogen while too young can apparently promote too much stem/leaf growth… taking energy away from root growth).

    Anyhoo… peace and good luck!!!



  2. Sage on


    In case it wasn’t clear… Bake the soil. NOT the seeds or seedlings!!!


  3. Pingback: Tomato Seedlings - An Owner’s Manual

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