Vegetables Gardening - Growing Organic Vegetables

Group:  Below is an exchange I had recently with a good woman who is trying to grow her own seedlings, but not following the laws of plant growth very well.  Enjoy and profit from someone else's mistakes

18" box filled with 25% sand and 75% peat (pg. 180)  I don't know where David came up with 75/25 as the ideal, but I like 4 parts sawdust, 2 parts sand, and 1 part perlite.  This should NOT have been a major part of your problem, however.

add 2 T lime and 1 1/2 t. weekly feed. hand mix, water, (pg. 181). add seeds not too deep, cover with rubber drawer liner, place on heating mat to 75 degrees, cover with 6 mil clear plastic, and water with plain water until they sprout. Growing from seeds you apply ONLY the Pre-Plant Mix (lime, Epsom Salt, and 20 Mule Team Borax in the ratio of 80-4-1) to the soil.  And the amount is 3 level tablespoons per 18" X 18" flat.

Seeds are covered 2 12 times the seed THICKNESS, covered with wet burlap (rubber drawer liner with "millions" of holes in it is probably ok, but burlap is preferred.

I have never recommended covering the flats with greenhouse - or any other - plastic.  Air is the 3rd law of plant growth and plants will suffocate quickly without adequate air.  The plastic is very likely to also increase the air temperatures around the tiny plants above the prescribed 75-80 degrees.  If you are using the GH plastic to create a greenhouse within a greenhouse it may be ok, but it must be substantially ABOVE the seedlings, and there must be some air circulation.  AND you must watch the air temperature, so that it does not go above 890 degrees F.

NO Weekly Feed is applied to the soil until you are TRANSPLANTING.  And at that time you apply 3 tablespoons Pre-Plant and 1 1/2 tablespoons Weekly Feed per 18" X 18" flat. 

as soon as they sprout, uncover with drawer liner, set in full sun, while keeping covered in plastic and on heating mat, and water with constant feed (dilute fertilizer solution) every time they are watered, with my can with the holes. (pg 183). 

When seedlings sprout immediately water with Constant Feed Solution (16 ounces Weekly Feed in 55 gallon drum of water - or a scant 1 ounce in 3 gallons of water).  THEN remove the burlap or shelf liner.

When your seedlings sprout full sunlight is fine, so long as you do not let the temperature on the seedlings get to high.  I suspect you may have cooked the tiny seedlings.

About two days later, I have the cutest little sprouts ever, all in perfect lines.  I cover with plastic at night (we are an hour north of Austin), and uncover during the day, but they remain on the heat mat.

Do you have a soil-probe thermometer and an air thermometer?  It's good to maintain the soil temperatures, but in Texas with direct sunlight you will VERY QUICKLY get temperatures that are substantially in excess of 80 degrees when you have a heat mat plugged in plus plastic over your plants.

TEMPERATURE is so critical, and can get out of hand very quickly.  And tiny seedlings are very vulnerable - as you have discovered.,

About day 4, I now find myself just sitting on a bench staring at my soon to be prolific garden. I have visions of the robust flourishing bushels they will become.  

Then, about day 6, they are just dead.  Skinny, laying over, just dead.

So, some things I think I have done wrong…

I am using the same constant feed from last year. Do you think it gets old?  Only thing is these guys died last year when the constant feed was a week old. BUT what is the shelf life of constant feed do you think?

Are you saying you are using Weekly Feed that you mixed up last year?  If so that should not be a problem.  The shelf life of the mineral nutrients is very long indeed.


Last year, I didn't use the heating mats. So I thought that would fix the problem this year.  But I did put them in the direct Sun after they germinated (radishes for example, late January.) And after a day in the sun…dead.

Too much LIGHT is not the problem, but the accompanying HEAT is likely the culprit.


This year, I am wondering if I baked them by them being on the heating mat and covered with plastic during the day. Which is why I would take the plastic off during the day.

I am confident heat is the primary issue - and maybe lack of air.

Sooo, I guess I have a lot of questions.

1.  shelf life on constant feed - Not a problem unless you have left the LIQUID Constant Feed for weeks or months, in which case the nitrogen could have been lost through volitalization into the air.

2. If my weekly feed gets wet, can I dry it out and reuse it?  Weekly Feed can be used wet or dry.

3.  I am so confused on how long they stay on the heating mat.  Temperatures of both soil - before germination soil only is critical - and air are to be in the 70-85 range.

4.  Is 75 the right temp?  Make sure the temps do not go above the range named above day or night.


5.  Do they stay under the plastic everyday?  Or am I doing right to uncover them during the day and cover at night?  I do NOT recommend having plastic over your trays unless the air temperaturse are below 60 degrees, and they must be watched because sunlight will raise that temperature into the danger zone very quickly.

6.  To keep the soil moist, would you say you water them every other day?  I wonder if I am watering too much each time or too little.  Maybe you could give me a very general "a can a day" or "a can every other day" type example.  It usually takes about 2 cans to water a flat.  You must learn to feel the soil to know when to water.  in warm and sunny situations daily watering will be necessary, and if it gets hot more often may be necessary.

7.  My last question is if I could send you my spreadsheet of what I put in when and see if it resonated with what you did in Houston. Of course, I use the Mitt. Garden Planting Details for Mitt. Garden you handed out at the conference. I was just going to see if you would glance at my plan and see if any of it seemed off.  I'm happy to look at what you have done.

Jim Kennard

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