Seed starting failure...

So, I'm not really a new gardener, but I'm new to starting seeds indoors. In the past, I either bought started plants, or simply didn't plant stuff that needed a longer-than-natural growing season for my area.

So, I have heat under my shelves which I have adjusted temps (between 50 and 70 F) for each seed type (early it was broccoli, cauliflower, and the like, I gave up. Recently it is tomatos and peppers), and have had brilliant success with germination. I have delighted in watching the seedlings reach their little cotyledons towards the lights (which seemed to me to be far too close, but I learned from my first attempt that one is necessary!) kept an eye on the dampness, letting them never get dry but not allowing them to have wet feet either. Some early ones had a cobwebby fungus problem, but someone's suggestion (on this forum) of putting a tiny bit of H2O2 in with my H2O and a fan providing a gentle breeze seems to have completely cleared up this problem in subsequent starts... I thought maybe damping off was the problem, so along with the H2O2 and the fan, I started topping off the starting pots with granite grit to help keep the surface dry near the base of the stem...

But I haven't been able to get ANY of them to live through their first set of true leaves. Basically, I'm out of ideas, I've checked the soil, the heat, the lighting, the water, the... everything I can come up with. Last night I had lovely strong looking tomato seedlings, and this morning I have shriveled up sad little hairs laying on top of the soil. Literally, only about 7 hours after the last time I checked on them. This is the same pattern as every set I've tried.

Makes my heart sink.

Does anyone have any other ideas? I'm running out of time before it's largely pointless to start things indoors for this growing season!

Thanks in advance.

Wanted: new brain

needsnewbrain - what kind of soil are you using? If it's a packaged type, please let me know what it's called. If you mix your own, let me know what you put in it. If you used soil from outside, let me know that, too.

I'll help if I can....

It sounds like the heat might be too hot. Could your lights be cooking your plants?

Brainiac,
Could you post a picture of your setup and your seedlings? Maybe we can determine what's going on if we can see a pic.

Linda

To me, it sounds like you have what is called "Damping off". It is a fungus problem and causes the seedling to wilt almost instantly. Do your seedlings have an area just above ground where the stem looks thin and shriveled? If you dig a seedling up, does the shriveled stem go below ground? Here's a photo of damping off from West Virginia University, http://www.caf.wvu.edu/resm/aee/cde/plantpath/CD/Tomato.html.

You can get more information by searching Google, but here is a page the might help you get started. http://www.avrdc.org/pdf/tomato/damping_off.pdf The best thing you can do is to be sure that you use sterile seed starting mix and that your starting containers are clean with no soil from earlier plantings.

David