I messed up, not terminal yet, need advice from experienced growers...

I switched my seedlings to HPS prematurely. They have been under the HPS for four days. The HPS is 4' above the seedlings but I'm starting to see signs of heat/light stress the last couple days.

The soil medium has no nutes... just peat, verm., pearl.

My temp is running about 85f and humidity is 55%. I have a 10" fan blowing directly at the light from 2' away. Also, a 13" fan for exhaust, and a 16" fan to intake cool air, both in the door of a clothes closet I'm growing in. The only impact the fans are directly having on the seedlings is the very slightest indication of a breeze.

Watering has been monitored very closely... The soil in the tray pockets gets dry about every 24 hr, I water with a dropper until the first drop comes out the bottom.

Should I switch back to the fluoro's or weather this thing out? (seedlings are 2 1/2 weeks old)

Light Stress??? Not sure if I get this one seeing that your light has nothing on the sun. Also not so sure you should be watering everyday. If they r seedlings just keep the top layer moist. Without pictures and more information I doubt you will get very many people's input.

How many HPS watts? 4-5 feet is about the maximum range for a 1000w HPS. For a 400 watter, perhaps 3 feet maximum. Beyond those ranges, very little energy is available to promote photosynthesis. Like trying to light a joint from two feet away. The flame is hot enough, it's just unusable at that distance. Plus, the heat will dry-out the medium much quicker, especially in the smaller cups.

Fluoro's work fine, and some prefer them in early stages. (rooting clones, developing seedlings) Easier watering schedule and easier on the seedlings.

A picture would help.

The HPS is 400w. The camera I have access to will not focus when I get close enough to the plant to display the brownish spot. I have researched the data available on the site and the pics that were similar to mine were described as being caused by heat/light stress. I'm new, so maybe there is no such thing as light stress. I was simply repeating what I read.

The bottom line is: I moved seedlings under the HPS before I should have (1 1/2 wks). My only real question is: what is the potential harm if I put the seedlings back under the fluoro's until they aren't seedlings anymore?

Rusty, I appreciate your response. I was not aware that 4' could be too far away. (especially in the case of seedlings)

Well, unless I'm cautioned against it, I'm going to put them back under the fluoro's for a week or so.

There's nothing wrong (no harm) with using flouro's for the growth stage. :thumbsup:

They seem happier already. :thumbsup: