lights on/off per 24 hours?? - Page 2

Ozark · March 11, 2016

I agree, 16 hours on, 8 hours off.

So many things in nature key in on the length of daylight to do certain things in relation to the time of year. At our latitude here, our longest days of summer in late June have about 16 hours of daylight and 8 hours of dark. So, by giving my seedlings 16 hours of light I'm 'fooling' them in March and April to 'think' it's already June - that they're running behind schedule, and must do extra well to catch up.

That's my theory anyway, and whether it's right or not I raise some real nice seedlings by following it.

Merediana · March 11, 2016

Quote:

Originally Posted by bower

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.

This time I'll make a comparison, I've put some seedlings at the window with natural light and some under my growing lights, same varieties, same age, same pot size, potting mix etc... The only thing that worries me is that this spring is still kind of dark, they only have around 9-10h daylight and not much sun because of the bad weather

Worth1 · March 11, 2016

Most amount of hours in Alaska from sun up to sun down in the Anchorage area where most of the people live is just a little over 19 hours.
The rest of the time is more of a twilight period where the sun is just below the horizon.
Starting at the arctic circle you get one full day of 24 hour sun and the farther north you go the 24 hour days will start to add up.

Visions of people walking around at midnight with the sun full overhead this far north is a misconception derived from the movies and TV shows like Northern Exposure that was filmed in Washington state.

Worth

amideutch · March 12, 2016

Check out this thread for your answer.

Ami

http://www.tomatoville.com/showthread.php?t=13171

bower · March 12, 2016

There it is.. "The tomato is a facultative short day plant which flowers and fruits earliest if the day is not extended beyond 12 hours by artificial light."

I should have a room for my seedlings, where I'm not strutting about after dark and leaving their lights on for my own benefit.

flyfiishn · March 14, 2016

I go 16 on 8 off as well. Mimicking normal summer daylight hours.

sjamesNorway · March 19, 2016

Craig LeHoullier, in "Epic Tomatoes" writes, "Research indicates that the optimum amount of time for tomato seedlings under light is 14 hours" (p. 163). That's what I use.

Steve

SharonRossy · March 19, 2016

Bower, you're right, last year I had left my lights on for 18 hours and they grew really fast and started setting flowers which eventually fell off. I started another thread but I think this is where my answer will be. I use the T5 HO lights and was wondering what should be the best amount of time with the lights on. My seedlings will be in a room with good light but they will not be exposed to direct sunlight, and I was also wondering how many lights I should be using. Right now, I have one set of lights, 48" with three T5 lights, the other is 36" with 3 lights. Do you think that is enough to light for approximately 60 seedlings? And is 14 hours enough or do I go for 16? Of course, I could always compromise and set it at 15!

I'm only starting my seeds at the end of March, first week of April.
Sharon

User 636 · March 19, 2016

I have mine on a timer. They turn on at 6 and off at midnight. The seedlings are looking great and not leggy.

March 12, 2016	#19
amideutch Tomatovillian™ Join Date: Feb 2006 Location: Germany 49°26"N 07°36"E Posts: 5,041	Check out this thread for your answer. Ami http://www.tomatoville.com/showthread.php?t=13171 __________________ Life's journey is not to arrive at the grave safely in a well preserved body, but rather to skid in sideways, totally worn out, shouting ‘...Holy Crap .....What a ride!'

March 19, 2016	#22
sjamesNorway Tomatovillian™ Join Date: Oct 2014 Location: Norway Posts: 1,049	Optimum = 14 hours Craig LeHoullier, in "Epic Tomatoes" writes, "Research indicates that the optimum amount of time for tomato seedlings under light is 14 hours" (p. 163). That's what I use. Steve

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March 11, 2016	#16
Ozark Tomatovillian™ Join Date: Jan 2008 Location: Ozark, Mo. Posts: 201	I agree, 16 hours on, 8 hours off. So many things in nature key in on the length of daylight to do certain things in relation to the time of year. At our latitude here, our longest days of summer in late June have about 16 hours of daylight and 8 hours of dark. So, by giving my seedlings 16 hours of light I'm 'fooling' them in March and April to 'think' it's already June - that they're running behind schedule, and must do extra well to catch up. That's my theory anyway, and whether it's right or not I raise some real nice seedlings by following it.

March 11, 2016	#18
Worth1 Tomatovillian™ Join Date: Feb 2006 Location: Den of Drunken Fools Posts: 38,539	Most amount of hours in Alaska from sun up to sun down in the Anchorage area where most of the people live is just a little over 19 hours. The rest of the time is more of a twilight period where the sun is just below the horizon. Starting at the arctic circle you get one full day of 24 hour sun and the farther north you go the 24 hour days will start to add up. Visions of people walking around at midnight with the sun full overhead this far north is a misconception derived from the movies and TV shows like Northern Exposure that was filmed in Washington state. Worth

March 12, 2016	#20
bower Tomatovillian™ Join Date: Feb 2012 Location: Newfoundland, Canada Posts: 6,794	There it is.. "The tomato is a facultative short day plant which flowers and fruits earliest if the day is not extended beyond 12 hours by artificial light." I should have a room for my seedlings, where I'm not strutting about after dark and leaving their lights on for my own benefit.

March 14, 2016	#21
flyfiishn Tomatovillian™ Join Date: May 2014 Location: Northern CA Posts: 80	I go 16 on 8 off as well. Mimicking normal summer daylight hours.

March 19, 2016	#23
SharonRossy Tomatovillian™ Join Date: Jul 2012 Location: Montreal Posts: 1,140	Bower, you're right, last year I had left my lights on for 18 hours and they grew really fast and started setting flowers which eventually fell off. I started another thread but I think this is where my answer will be. I use the T5 HO lights and was wondering what should be the best amount of time with the lights on. My seedlings will be in a room with good light but they will not be exposed to direct sunlight, and I was also wondering how many lights I should be using. Right now, I have one set of lights, 48" with three T5 lights, the other is 36" with 3 lights. Do you think that is enough to light for approximately 60 seedlings? And is 14 hours enough or do I go for 16? Of course, I could always compromise and set it at 15! I'm only starting my seeds at the end of March, first week of April. Sharon

March 19, 2016	#24
User 636 Tomatovillian™ Join Date: May 2015 Location: Virginia Posts: 36	I have mine on a timer. They turn on at 6 and off at midnight. The seedlings are looking great and not leggy.