Hello
Please my question is : do the same plant will stretch the same with HPS lamps and led lamps ?
Thank you very much and good day
3 Likes
That’s one experiment I’ve never done, only because I don’t grow with MH/HPS anymore because I gave them all away and use up way too much electricity…
6 Likes
Thank you
Your plant stretch a little with LEDs ?
Because I have a SOG 50% full and I think it’s time to switch to 12/12 but never saw a stretch with LEDs
(I know veg is really slow with LEDs that’s why I ask before making shit maby)
Thank you a lot
1 Like
In my experience, yes strains can stretch during the start of 12/12 under LED and HPS.
I find that it depends on the strain and other factors (like difference between daytime and nighttime temperatures, overall light intensity, what method you are using for growing, what you’re feeding, etc.)
1 Like
I’m not positive but I think it was KIS organics podcast episode 127 “flushing and photoperiod research with Michael Alden” that they talked about what light spectrums cause more stretch vs more compact plants. Good episode either way though!
Look into what different light spectrums do, (more blue, red, far red, etc.), and that’ll answer your question better, because especially with LEDs, spectrum varies a ton. I think it was grandmasterled that put out some lights recently with full spectrum tuning capabilities
3 Likes
I used to run 400w or 600w hps and always got stretch, now with just 250w led no stretch. Same light height
2 Likes
Thank you
Even sativas no stretch ?
1 Like
Some really good info here on stretch.
6 Likes
Ive not done heavy sativas under led but no stretch to talk of on hybrids or indicas. I am glad swapped from hps fo lots of reasons now. Temps, light spectrum for inspecting plants, yield, electric etc. I should say though I do run 12/12 from seed so the plants are not fully mature when they flower.
2 Likes
Very cool, thank you, it’s what I want to do
How much average yield per plant, you obtain when you start 12/12 from seeds with LEDs ?
I would say crop steering and temperature are what matters most with stretch
Yes light spectrum plays a big factor
But regardless of your light, you can try and “steer” your plant
That isn’t to say I know how 
But it’s possible
1 Like
In general I would say HPS causes taller plants than LED.
They produce more heat, most HPS grows will be running hotter than LED and they produce IR light which is also a trigger for plants to stretch.
led spectrum can be anything though, some fixtures have IR diodes, and with the right climate control temps can be whatever you want.
2 Likes
Usually, plants stretch a tad more under HPS lights than LEDs, but it really depends on the plant and stuff like that
2 Likes
It depends on strain and pot size but minimum 1oz up to about 4 oz per plant, using soil.
1 Like
I have not found this to be the case at all. I get vegetative growth as fast and vigorous, and in most cases better than I did when I ran HID lighting. I wonder what factor is causing you to have a different experience.
1 Like
Are you adjusting your PPFD’s when flipping?
I found stretching and node-spacing wasn’t great until I started accounting for PPFD. This and consistent magnesium supplement I found really helped anything under LED’s.
4 Likes
Thank you
You are right. I have to see the other factors like temperature, because with LEDs it’s not the same
Thank you
Please what is PPFD ?
1 Like
PPFD is photosynthetic photon flux density . PPFD measures the amount of PAR that actually arrives at the plant, or as a scientist might say: “the number of photosynthetically active photons that fall on a given surface each second”.
There are 86,400 seconds in a day (3600 x 24 hours) so the daily PPFD can be calculated directly from the instantaneous PPFD from the following equation: µmol m-2 s-1 multiplied by 86,400 and divided by 1,000,000 = mol m-2 d-1.
So: 1 µmol m-2 s-1 = 0.0864 mol m-2 d-1 with continuous light
These conversions are accurate only under electric lights. The integrated daily PPFD from sunlight changes during the day so a single measurement cannot be used to estimate daily PPFD.
That’s a copy and paste. 
7 Likes
Fun answer:
“Like Brawndo, it’s what plants crave.”
Science answer:
"PPFD is photosynthetic photon flux density. PPFD measures the amount of PAR that actually arrives at the plant, or as a scientist might say: “the number of photosynthetically active photons that fall on a given surface each second”.:
Once you know your PPFD you can then dial in your DLI…
…which is:
Daily light integral (DLI) describes the number of photosynthetically active photons (individual particles of light in the 400-700 nm range) that are delivered to a specific area over a 24-hour period. This variable is particularly useful to describe the light environment of plants.
It’s more $ to spend but if you get a PAR meter you can then find out your PPFD and then adjust for your DLI. (PAR is photosynthetic active radiation. PAR light is the wavelengths of light within the visible range of 400 to 700 nanometers (nm) which drive photosynthesis)
It’s all very scientific to get the max out of a plant by ensuring it gets the highest amount of usable light before burning or wasting.
Here’s a crazy chart showing how someone mapped this all out:
And here’s what I like to look at instead 
I don’t CO2 so I stay maxed out at 1050.
As an example; in my 4x4 the lights are cranked at a PPFD of 1050 for flowering and at 12/12 lighting period. In my vegging tents they are dimmed down to 250 at 24/0.
All this because of winter… and also SCIENCE!
7 Likes