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So I started my seeds (Green Pepper, Tomato, Eggplant and a few herbs) about 4 weeks ago and I JUST noticed that my timer was set to always be on! It has a switch where it will stay on at all times or just be on as the timer is set and I must have accidentally had it set to stay on at all times.

This was only my second year starting my own seeds but I noticed they seem like they are not growing as fast as last year. Could this be caused by the lights being on or is it just in my head? My tomato's are only about 3 inches tall and I was going to up-pot them this weekend. What else does this do to the seedlings?

Hopefully I (or someone else even) can learn from my mistake

Not everyone will agree with me, but I think plants do need and benefit from a rest period of darkness. They have different processes going on in the dark than the light. They can handle up to 18 hrs a day of artificial light (less intense than sunlight), after that they start getting stressed.

I don't know that that is the only thing going on why your tomatoes are still small.

Its not the best thing for optimal growth, which is why commercial nurseries do not use 24h lighting for seedlings, but for your varieties it will has not really screwed them up in any way.

I do have to disagree with RBG! Last year, a guy tried an experiment comparing the same type of seedlings growing under continuous light and 18 hour cycles. He experienced significantly more growth under the 24/7 lighting. A couple of studies produced the same results but found that after 6-8 weeks, the plants did start stressing.


Mike

I had great results last year (first year trying) with lights on 16hrs a day. That's what I was shooting for again this year.

Rainbow, I'm nit sure if my plants are small or not...I don't really have a whole lot to compare them to. This is the first year I'm keeping an electronic journal including pictures as the plants progress...

I just checked this forum for info. on this very topic. I've forgotten to move mine out of the light overnight a few times. I recently saw a documentary about plants on History/Discovery/Nat Geo/ or Science channel (can't remember which). I learned that plants do have a biological clock. I'm guessing that 24/7 light on occasion isn't too harmful, but the plants don't like it and will not respond well if it is continued for too long.

That is my experience too. If I forget for a day here and there it doesn't matter. But I have tried leaving them on all the time and for me in my conditions, the plants do seem to suffer.

I don't know how, but about 388 of my Celebrity tomato plants have disappeared. OK, I had a few from a couple of trays left over, but best guesstimates put the MIA total at 324. Not that things disappearing around here is a rarity - it tends to happen all the time. But they usually show back up!

I'm not taking any chances as I don't have any Celebs to transplant in my garden, unless I don't sell them all. Yesterday, I sowed about 150 seeds. The soil and water are both warm ~ 75 degrees, so it should not take but a few days to germinate. Once they do, under a light they go - a 400-watt MH running constantly. When transplanted, they will go into a potting mix with a decent amount of Blood Meal and Tomato-Tone, and every other watering will be with a solution of TT.

The goal is to have at least 6" plants, with four sets of leaves, by Memorial Day.

Progress reports will be provided!

Mike

I am running 315 watts fluorescent over top of my seedlings from dawn until dusk and they are bleaching out. Plants can only move so much sugar (photosynthate) out of the leaves in a given amount of time, and if there is a backup from too much light the plant will reduce its chlorophyll or produce red pigment to block the light, so for 24/7 you will have to adjust the light level.

This is why I have - and use! - a light meter!

Mike