I don't have right answer to your question, just my experience: last winter I used CFL's, positioned approx. 2-3" above the plants. I think some plants are more sensitive than others. See photo for burns...

I didn't expect the heat from CFL to be so strong. Now, I would try bigger distance & slowly move them closer if necessary.
Rina

How big was your CFL in terms of wattage? or lumens?
Are these damages really caused by the light?

Sorry, I could not remember the wattage/lumens & I am not home to check, but I will (I think it was 60W). I remember looking for highest lumens when shopping for light bulbs. And damage was definitely caused by heat from the bulb, I moved the pot closer (it was at least 6" away or more before), and within 1/2 hour this is what happened.
The plant recovered, but it took long time.

Edited for remark:Photo below shows the same plant year later-recovered.
Rina

This post was edited by rina_ on Thu, Oct 24, 13 at 10:56

I also think you are getting too much light, I never thought I would be saying that, but I think if you moved your light away till you were getting about 1000 fc that would be enough. Al

Thanks Rina and Al for your inputs.

Could this high intensity light be the reason that my pepper and cherry tomato seedlings are too slow to grow? They are growing too slow (if at all). In the past week or so, I haven't seen any noticeable change? No true leaves at all although the cherry tomatoes and one pepper seedling opened up their seed leaves since last 2 weeks. I can also see some burned edges (brown colored) of the seed leaves.

Saood

Here is the photo of CFL I used - 23W, 1650 lumens.

Rina

OMG! it was 23W and it caused that damage in half an hour! Mine are a close 20W. Practically the same. I have taken the CFLs further away. The reading now is around 1200-1300 fc by keeping it 9-10 inches above the seedlings.

Thanks Rina.

Saood

I would just watch the seedling for etoliation, and if necessary, move them slowly closer to the light bulb - just like moving plants from inside to outside for the summer, they need to get used to stronger light. I am using same light bulbs again (this is for my 'winter'-inside home for the sensitive plants), plants are approx. 4-5" away - no burning this time.

You asked if there may be too much light on your tomato and pepper seedlings - I don't know for sure, but think that these plants like lots of sunlight and longer days and warmth. When I start from seeds, I keep trays really close to lights (2-3") otherwise they get really etoliated. Look at the photo of some of my tomato seedlings (spring 2013), I think they are little etoliated - this try was just by the south window and no supplemental lighting.
I wonder if there is anything else slowing growth of your seedlings.
Rina

This post was edited by rina_ on Fri, Oct 25, 13 at 10:35

I was late with starting seeds this year, but they still grew very well (same plants 2 mo later, potted up 2nd time). I also planted 20 asparagus seeds, and 17 of them are growing well (see little ferny plants in the photo attached).

Do you have photo of your seedlings? Pls. post.

Rina

This post was edited by rina_ on Mon, Oct 28, 13 at 8:43