Problem with tomato seedlings
Around March 7 I started tomato seedlings. They germinated fine but since then have not done well. The top of the leaves are very dark green and the underside of the leaves and stems are reddish-purple. As the weeks have gone by the older leaves have started to shrivel up. The photos are not great quality but probably give some idea of what I am talking about.
Last year my tomato seedlings grew great using the same lights, seed starting mix etc. I use 4 foot T8 shoplights with one 'warm' bulb and one 'cool-blue' bulb in each fixture. The seed starting mix was from Jiffy. My approach to watering is the same as last year e.g. I check them twice a day and water as needed to keep the surface somewhere between damp and somewhat dry (but with weight to indicate that soil below is moist) All of my other plants (including eggplant and peppers) are doing well. So the whole thing is very strange. The only think I can think of that I am doing differently is that I am using a 17 hr light/7 hr dark cycle whereas last year is was more like 14/10. Am I using too much light? Is it a plant disease that only affects tomatoes? I'm really bummed by this because I have all these exotic varieties growing that I won't be able to find at Home Depot!
Here is a link that might be useful: sick tomatoes