Lighting schedule for germination

[The Haroo ln]

Hey guys, I will be starting g my 2nd grow of tobacco in April this year. I learnt a lot from my 1st one from last year but just wanted to brush up and fine tune my knowledge a little. When germinating seeds should the lights be on 24hrs a day? And when do I need to change the lighting schedule and introduce nights/turning off lights to plants before transplanting?

 

[wruk53]

Hey guys, I will be starting g my 2nd grow of tobacco in April this year. I learnt a lot from my 1st one from last year but just wanted to brush up and fine tune my knowledge a little. When germinating seeds should the lights be on 24hrs a day? And when do I need to change the lighting schedule and introduce nights/turning off lights to plants before transplanting?

I usually run my lights for 15 hours per day during germination and I don't change anything before transplanting outside.

 

[ProZachJ]

This year I chose my light cycle based on the daylight hours that will be in place on the week I intend to transplant.

 

[The Haroo ln]

I saw from a few places that the initial germination needs 24hr lighting, once the the leaves have sprouted and thinned out/repotted (usually after 2-3 weeks) they can be put under normal lighting conditions with at least 10-12 hrs on and 10-12 hrs off. Just wondering if that's true and how that would affect the seedlings. Last year I ran them on 24hr lights up until I transplanted them into the garden. The first pic was around 2-3 weeks after germination and then the 2nd pic was 1 week before I transplanted outside

 

[GreenDragon]

I’ve always used a 10-12 hour light cycle for germinating seeds through transplanting.

 

[deluxestogie]

Just wondering if that's true

It is not. Some tobacco varieties require a brief (less than a minute) exposure to light, before they will germinate. Most varieties require no exposure to light, prior to germination. To test that, one year I mixed each tobacco variety's seed in its own Mason jar of my starting mix soil, shaking each jar to distribute the seeds throughout the jar. These were placed in a warm location within a darkened room. When seed began to germinate (all of them did), it was visible through the glass side of the jar, as a bright white dot. At that point, I would dump out the contents of the jar onto a baking sheet, then transfer the individual, germinated seeds to my 1020 trays using a single blade of forceps as though it were a flat toothpick.

There is a lot of mythology surrounding artificial lighting for young seedlings. Just remember that if the seedlings are regularly exposed to a shorter dark period per day (that is, more hours of light) than the outdoors at time of transplant, then they may respond to the lengthened dark period by initiating bud formation too early.

Bob