lights on/off per 24 hours??

[RomanX]

Between last year and now, it seems I forgot how many hours per day to have the floureascent lights on for my tomato seedlings. I figurre I've got about three days until I MUST turn them on, so HELP. PLEASE!!

[pmcgrady]

Mine are on 12 to 14 hours, seedlings are looking nice.

[Cole_Robbie]

I think consensus is 12-16. I usually run mine 24 when I need the heat. I will shut them off on afternoons for a few hours if things get too hot. As soon as they go into six-packs, they go into the greenhouse and get whatever hours the sun shines.

[TightenUp]

16 on 8 off

[kath]

Originally Posted by TightenUp

16 on 8 off

This is what I shoot for- they go off when I go to sleep and go back on when I wake up.

[heirloomtomaguy]

I give em 17 hours on 7 hours off. Why? Because i set the timers that way long ago and have yet to change it.

[Merediana]

Uhm, whenever I make it out of bed till I go to sleep again It worked great for my peppers and eggplants and it now seems to work for the tomatoes, too.
Last week I haven't had much sleep because I had to do so much work for university and after around 16h the seedling were folding their leafs up. Seems like they couldn't handle more light...

[jessleigh]

Ive run em 24 hours a day and had no problems. I always forget to turn em back on whrn i shutem off..... and havent bought a timer out of lazinessmormforgetfulness, im notmsure which haha

[bower]

From what I've read, the usual recommendation is to let the poor dears get their 8 hours sleep. I like my eight hours too, so it's easy to follow that without a timer. Gives them more of a day/night difference in temperature too, which afaik is healthy for them.
Sharon Rossy had some strange results last year we thought may be caused by lights on more than 16 hours, there's a thread here somewhere... I don't know if others have had similar issues. HTG I guess you're proof that 17 is also not a problem.
Also, if you really need the heat as Cole does, of course you have to leave em on.
One thing I've noticed by trying different light regimens, I got the earliest flowering dates under natural light conditions, that is spring day lengths closer to 12 than 16 hours.

[PureHarvest]

I've done 24 hrs of light and the plants did ok
But then I think about the fact that plants respirate during dark. Respiration takes the energy that was made by light /photosynthesis during the day and sends the energy/products throughout the plants at night.
I only did the 24 hr day a long time ago and now wonder if I limited my plants potential even though they looked ok

[Worth1]

I dropped mine back to 12 or 13 on and they did great.
Worth

[kurt]

It is all about the oxygen/Co2 exchange for the plants photosynthesis requirements.Different plants vary in their needs at particular growing stages.Maters are/can be bred for seasonal differences.Alaskans have a good record for producing large plants/produce with 24hr daylight sequences but shorter warmth periods.12hr on 12 hour off is a norm for me.Plenty of variables to consider.Cannabis growers use different lighting cycles for optimal bud formation.

http://scienceline.ucsb.edu/getkey.php?key=2860

http://scienceline.ucsb.edu/getkey.php?key=3375

[brownrexx]

14 hours on for mine.

[BigVanVader]

Ya I find anywhere from 12 to 18 hours works great.

[AlittleSalt]

I have two rooms where they get different amounts of light.

One is where I sleep with very heavy curtains, so whenever I get up I plug in the florescent lights until 10pm.

The other room has lots of natural light first thing in the morning and florescent lights when I plug them in until 10pm.

So...yeah...the perfect 16/8 thing