Question
This is the 1st year I started vegetables from seed.  I started some 4th of July tomatoes and they came up well but now I only have 2 that didn't die and they seem to be yellowing.  I only water when the soil is dry, I used a "Soil-less" starting mix and I have a flouresent light (the kitchen light is what I am currently using).  Where did I go wrong?


Answer
Christopher, the reason your seedlings are dying shortly after germination is due to a disease called 揹amping-off?  Damp-off is caused by one of three factors. These include contaminated soil, poor air circulation, or water-logged soil.

I always recommend purchasing sterilized starting medium for seedlings.  You can buy this by the bag at most garden centers and nurseries.  This combination of perlite, vermiculite, and peat moss is light and airy, therefore allowing the young seedlings to receive plenty of oxygen through their roots.  But most importantly, it is sterile, virtually eliminating any chance of damping off.  But given the fact you are using a soiless mix, this most likely is not your problem.

Contamination can also be caused by unclean flats and/or pots.  At the end of every growing season, if you choose to reuse the same flats next year, make sure you sterilize them in a solution of one tsp. of bleach per gallon of warm water.

The other possibility is a lack of air circulation.  Many seed starters cover their flats with a plastic dome to retain moisture and aid germination.  If using this procedure, it is very important to remove the cover once the first seed germinates.  Otherwise, the lack of air can prove fatal to the yound seedlings.

If you're not using a covering, you may need to improve the air circulation by using a fan.  Make sure you keep it at least three feet away from the flats and keep the setting on low. The fan must rotate to keep the air moving.

Finally, do not overwater.  Water-logged soil deprives the soil of oxygen and nutrients.  Your flats and pots must have a drainage hole or else the process will fail.

In summary, let me give you some tips on growing plants from seed.  This is my standard instructional document that I send to all new seed starters, so some of it may be redundant with what I have stated above.

Seedlings need to be in simulated sunshine for at least 14 hours per day.  They also need 8 hours of dormancy for good growth.  You either need to invest in fluorescent bulbs called gro-lights which are as close to natural light as anything sold on the market, or substitute these with less expensive bulbs. By using one cool and one warm white fluorescent in combination, you will achieve the same effect.

If given the correct conditions, namely adequate moisture, strong light, and healthy soil, the plants will germinate and grow to maturity with few or any problems.  To maintain moisture, seeds should be covered with plastic.  I grow my seedlings in seed trays with individual cell packs.  After sowing, I cover the flat with a pre-fitted plastic dome.  But once the first seedlings sprout, it is important to remove the cover to avoid damping-off disease.  

Once the seedlings develop their second set of leaves, you can begin supplementing the plants with a diluted solution of fertilizer.  Since you want to keep the nitrogen and salt levels low at this stage of growth, I highly recommend staying away from the chemical mixes.  Rather, use a seaweed/fish emulsion formula at ?the recommended level.  This will help the plants' development and also help ward off disease.  You can purchase these organic formulas at most garden centers or through online websites such as Gardens Alive.

Finally, be sure to keep your fluorescent lights no higher than 3?above the seedlings at all times.  This is critical to prevent the plants from becoming weak and spindly.  As I mentioned earlier, they should be left on 14 hours per day.  If fluorescent lighting is not possible, put them in a southwest window and turn them every three days to avoid leaning.

I am attaching a few websites that should prove helpful.  I would also advise you to purchase 揟he New Seed-Starters Handbook?by Nancy Bubel. It has many good ideas and techniques that benefit even experienced gardeners.

http://www.gardenguides.com/TipsandTechniques/starting.htm
http://muextension.missouri.edu/xplor/agguides/hort/g06570.htm
http://echonet.org/shopsite_sc/store/html/SeedStarterHandbook.html

Good luck, and have a great weekend.

Regards,

Mike