Seedling and veg lighting

[Biggbudzlova]

Hello. How much does light intensity matter. I’ve have 2 Maxsisun PB2000. I’ve been running them both at full power. The problem is some of my seedling sprout and the rest don’t. The ones that do sprout are usually long and lanky. And typically by week 3 of veg, they’ve grow the primary and secondary set of leaves with the third starting to show. But the stems are still very long and lanky. Seeming like there’s no stalk growth. I’ve seen a lot of videos on different sources and they all have about the same look. They’ll have short girls starting to bush or long and lanky but they’re still bushy and strong looking. With big full second and third sets of leaves. And they all have their lights dimmed down to 50% or 60%. Some leave their lights at that during most of the plant life. Some increase the intensity to 70%to 90%at about the 4-5 week just before flipping to flower. I’ve also seen folks with their lights on full blast during the entire run. Please someone help shead some light on this

 

[treefarmercharlie]

In my experience, and based on everything I’ve read, cannabis seeds sprout better in the dark. I keep my planted seeds in the dark until the break soil. Then I put the lights about 20” off the seedlings and dim them down to 50% power (or less) and then slowly ramp the lights up once they start throwing leaves. They need very little light when they break soil and even fluorescent tubes a few inches above them work perfectly for young seedlings.

 

[H.A.F.]

I have a mini tent with two 65w QB's. I start seeds with one of them, and I have them on 18/6 under a dome from day one. They get their dark, and the light provides what heat they get unless it's cold enough to warrant a heat-mat.

 

[Old ST1R]

In my experience, tall and lanky is due to not enough light.

Heisenbeans said it best himself - there is no light bulb that can match the power of the sun. If you don’t have a $1000 top of the line LED light, give the seedling a couple or few days of gentle light, then lower the light to 12 - 14” from the tops and let ‘er rip.

 

[Old ST1R]

BTW, hahaha! “Please shed some light on this”. I see what you did there.

 

[Old ST1R]

Also, you gotta have all the other boxes ticked too - media, fresh air, humidity, temperature and air circulation will all play a part in how well your plants grow.

 

[NoWaistedSpace]

I have a fan blowing on the seedlings after they sprout.
The wind triggers them to start growing a thicker stock for support from the beginning.
I have 6 in. "clip on" fans.
What all these guys said above also.

 

[treefarmercharlie]

We all forgot to mention heat. If you don’t have a seedling heat mat then get one and you will see a big difference in germination rate and speed.

 

[High kev]

I like charts

 

[High kev]

If your plants are growing long inbetween nodes or grow really tall stemsin the seedling stage then flop over. Your not giving them enough light. The plants are reaching for more light.

 

[NoWaistedSpace]

If your plants are growing long inbetween nodes or grow really tall stemsin the seedling stage then flop over. Your not giving them enough light. The plants are reaching for more light.

Lots of 660 red will make your plants stretch also in veg.
Over 4000K, there is very little green and red in the spectrum. (green is pretty important) 5000k and up, is almost all blue.
Now, if using mostly blue spectrum, they will be short and stocky, almost too short. You can add a small amount of "far red" and get some stretch in your veg stage. I try and keep it around 3500K, gives you a nice range of all the spectrum. There is so much to learn about these leds and how to use them correctly for a growers individual grow styles.
Nice charts!

 

[H.A.F.]

I'm not buying this one - Maybe for HPS or something.