Any plant needs a dark period of time each day (aka night) so they can use the energy they created during the day to grow at night. I don't think it's a good idea to keep the lights on 24/7...give em several hours at night with the lights off.

thanks catman,
so is the cotyledon closing normal? or did I manage to kill my new babies =( ? I hope I haven't yet....

Not sure if the cot leaves closing is normal for 24 hour light exposure, maybe there could be another cause. If they're just bending upwards so much that they almost close, they might be fine...if they're curled or some abnormal shape then I'd be more concerned.

I don't think it is all so simple. Consider Alaska where cabbages grow to monstrous sizes during periods of endless days.

But there is no question that tomatoes and peppers grow faster
at night--at least they do in my greenhouse. And, when germinating seeds, I have watched my trays carefully and hopefully during the daytime, only to be amazed by overnight progress towards a great sprout.

Different strokes for different species? Maybe/probably.
But I think most all plants have a way of adjusting to their environment, getting tuned in to nature/weather/
local conditions as they are.

in a word / yes /

larryw - never heard that about the cabbages before. Maybe the much lower intensity (or angle) of the sun that far north makes up for the lack of darkness...but down here in warmer areas we get intense light followed by darkness and considering the region where tomatoes come from I think they are better suited for night/day periods. Just my 2¢

Thanks for the replies, well their cotyledons opened up again this morning, and I think my fluorescent light was too hot, some of the tips seem kind of burnt....will make sure to have them a little further away from the light today. Right now they're just sitting at the window being blown at by the wind. =)

I posted this pic in a different tomato forum just a day or so ago. It shows different results for different hours of lights on/off. The 12 on/12 off appears to be the most vigorous growth. The 24 hours on & off seem to be the worst. I can personally vouch for not keeping the lights on 24/7--by accident, that happened last year and the plants were severely stunted, pale, scraggly.

{{gwi:1320409}}

Wow korney19!

That is about as dramatic example as I have ever seen! I knew that plants were supposed to do their growing at night like catman says, but I had not seen it tested before. Although I see that the experiment is about as old as I am. *grin*

Thanks for posting it.

Bets

I also don't think the answer to this is so simple. There have been other discussions here on this topic.

Here is a link that might be useful: Discussion about leaving the lights on

Seedlings will do great with 24/7 lighting, at least for the first 7-8 weeks. After that, they do not do as well in the long run. Proof is available via a search of this site.

Mike

If you're just using 24/7 light to start plants to go into the garden, then it works great. I did an experiment last year. Two sets of plants..one 16 hours of light, one 24 hours. The 24 hour plants were much bigger, produced faster, and produced much more over the season. I leave my lights on 24/7 for everything now. There is a thread out there that I documented my experiment in from last year. I used the peppers as examples but tomatoes were very similar.

Good luck,
Rick

Thanks, Rick. Your experiment is proof positive!

Mike

I leave my lights on 24/7 for everything now
Even for your house plants?

I was noticing my tomatoe plants were really growing at night. I marked the stake and 2 hours later I checked it and they grew over 1".