Is it possible that plants flower faster under LED’s? It’s my first go around with LED’s and it seems odd that every strain from pure sativas to indica heavy hybrids are all finishing almost exactly 1 week early. I’m about to harvest some Malawi and it will be the 5th strain I have harvested that finished a week early.
Temps and humidity has been a little low for the entire time but I don’t remember that affecting flowering times under the Metal Halide. Other than that I’m in soil and everything else is fairly normal.
12 Sol Strips and 2 Red/Blue strips. The Sol Strips are under powered with all 12 running on a 320 watt driver.
Both clones and seeds. 5 different strains from clone and 7 different strains from seed to be exact.
Before anyone asks… I ran a perpetual garden for about 5 years and grew dozens and dozens of strains. So I know when to harvest. I was actually letting these go a little longer than I prefer for my taste. I normally harvest at 20% amber and I let everything go 30%+ because they were running early.
Interesting, could be. There have be various reports abound wondering about similar results. Your spectrum is likely balanced much differently than your previous lighting which could be the significant factor. Don’t know what it would be in your spectrum, perhaps more far/deep red? Compared to metal halide, the led spectrum probably has a bit more light hitting the primary action spectra for chlorophyllA and B, overall (e.g. why blurple came into being). Another question might be, is the yield the same or different with the faster finish?
I can’t give an answer on yield since this is my first grow in a long time and all the strains I have are new to me. They seem to be yielding as expected all things considered. Malawi, Guawi and Malawi X Panama will all live up to their billing as big yielders.
Years ago when I flowered under a MH a 9 week strain would finish in 9 weeks, a 12 week strain in 12 weeks. Some a little sooner and some a little later when starting a new strain from 10 seeds. Now it seems a 9 week strain is ready in 7.5 weeks or a 12 week in 10.
Good morning Ray. I’m running something kinda similiar to yours. 4x5000k 4xred/blue cree 2x2700k.
Based on my findings so far I’d say you’re about right with what you’re saying. My veg was much shorter than with hps. They showed sex about a week sooner. And is producing a nice frost much faster.
Not going to say my light or spectrum is perfect. I have far too much red in which hasn’t done much to keep my node spacing in check. I’m tempted to swap out the 2700k for more 5000k as height is pretty limited.
One thing I did do last night was check the voltage of my driver. (Should have done it so much sooner) 24.7v it’s sat nicely at 24v now and seems to be running lot nicer. A lot less heat but I’m getting 263w watts from a 320w driver @24v
360ish is the max it will put out but I imagine the strips will burn up a lot faster.
I could imagine that quite a few variables could sneak in here(as to why) but I’d say the results sound like a fantastic improvement. If the stretch is managed (blue), it sounds as though you’ve put together a nicely balanced light source.
Perhaps related:
“In addition to the R:FR ratio, the researchers concluded that the total amount of far-red itself also impacted the time of flowering when the R:FR was below 3.5. This was most evident in late flowering genotypes, in which the flowering response could be enhanced by 14-21 days with the correct R:FR ratio and total far-red irradiation.”
yes! I have now logged about 5 harvests under my LED’s and the plants are definitely flowering faster. They are finishing from week 7 to week 8 instead of week 8 to week 9. These lights are very high in 660nm red, they’re 10% blue, 10% green, 80% red.
My LED’s have very little far-red - less than 1% - so that part of the study doesn’t match my results. But supposedly cannabis doesn’t use far red very much. Big difference with LED compared to HPS is that all HPS are mostly the same while the spectrum of LED’s is all over the place. I wouldn’t expect them to all act the same. For example Fluence has way more orange/yellow/green than P.L. Hortiled or Lumigrow. It took me about a year to figure out how the new lights are affecting the plants.
Very interesting. There are a variety of great studies out there regarding spectrum ratios that act on the known and specific cycles in plant physiology. And, as @Muleskinner notes, different plant species do respond differently. Some plants respond strongly while others are seemingly unaffected. Studies specifically for cannabis are not as prevalent and is what makes these types of results particularly interesting.
There are some other studies, in progress or otherwise, about putting cannabis “asleep” using a flash of FR. Short-day vs. Long-day. Which tends to indicate that it has some effect but I can’t find a specific scientific reference for canna.
Otherwise, there is some understanding about far red utilization: Advanced Biology, Kent
"Photoperiodism requires a mechanism for detecting the length of darkness. The best-known candidate for this job is a pale-blue light-sensitive protein called phytochrome. It exists in two interconvertible forms: Pr which absorbs red light (light with a wavelength of 660nm), and Pfr which absorbs far-red light (light with a wavelength of 730nm). Phytochrome is synthesised in its Pr form. Experiments with specific wavelengths of light show that Pr is converted into Pfr when exposed to red light, and that Pfr is converted back into Pr when exposed to far-red light or when in darkness. During the day, there is more Pfr than Pr because sunlight has a higher proportion of red light than far-red light. During the darkness of night, Pfr is gradually converted back into Pr. Thus the relative amounts of the two forms of phytochrome could indicate day length. It is thought that the balance between the two forms of phytochrome controls flowering in short-day and long-day plants. A build up of Pfr could stimulate flowering in long-day plants, whereas in short-day plants, Pfr could inhibit flowering. "
Certainly red in general promotes flowering so maybe that’s all there is to it. Faster to initiate flowering. And wonder, is that the primary difference? Pfr naturally down converts to Pr but this process is accelerated by far red (FR). I could see an argument that some FR in the general spectrum down converts a portion of the generated Pfr to Pr thus decreasing the amount of dark time needed to fully convert Pfr to Pr naturally. Whether this is important or not in this case, I have no idea. But, it is fascinating to think about. This stuff also clues one into what happens when you interrupt the sleep cycle. Cool stuff. I need to do some more reading, me thinks…
I’d say it’s related to the far red. As plants measure their days from far red (sunrise) to far red (sunset). The theory I’ve read stated that red in 730nm range , specifically at the end of the day makes the plants “go to sleep faster”. With a typical light it takes hours for plants to shut down daytime activities, adding the 730nm light supposedly cuts that down significantly. So I’d assume it works similar in mornings signaling the plants to wake up earlier. Therefore utilizing much more of the day for photosynthesis and development.
@ray and @ReikoX I’ve noticed the same phenomenon with SolStrips. Everything finishes a bit faster. If I were to estimate it, I’d say about 15% faster than HPS. I’d also agree that it’s probably because of the added blue spectrum compared to HPS. Closer to full sunlight in spectral quality.
I’ve also noticed that the pistils turn orange much faster than the trichomes develop, so the old rule of thumb of looking for 80% of pistils to turn to determine maturity doesn’t apply. Got to get out the scope and inspect the heads directly.
The other big difference is odor in late flower. Because SolStrips put so much less heat onto the canopy, the terpenes are not being evaporated off the plants at the same rate as HPS. Odors are greatly reduced. Finished flowers are still aromatic as ever, perhaps more so, because their lovely terps are still on the plant, not exhausted out the vent…
to make things more complicated, i’m using led screw-ins for clones/babies/veg, then moving abruptly to outdoors for stinky flowers.
can’t really add to this one yet. heh
I’m noticing increased/early resin production in my tent and the leaves on my missis amnesia auto have gone full autumnal about 10 days earlier than usual. Both tents are much better lit than before but i don’t believe that alone can account for early finishing. Temps are roughly the same as with the old cooltube setups so that aint it either. Must be colour temp related imo.
I should maybe add that my missis tent was set up for veg and flowering so i used 4 x 2700K and 4 x 4000K cob’s in her rig. Quite a bit of blue in that mix, maybe a bit too much but time will tell.
