Why go 24 hours lights on??

[spurr]

Only read a small amount of this thread, but subbing so I can read more at my leisure.

LOVE the info you're putting on here, spurr. Out of curiosity, do you have any scientific training (Ph.D, M.S., etc.)?

Getting a B.S. now in plant science, going for at least an M.S. in plant physiology; I am in my mid-thirties. Most of what I know i have taught myself from lots and lots and lots of reading, and talking to those with advanced degrees in plant science; as well as experimenting on my own. I have verified what I learned by using what I learned to grow cannabis...

 

[spurr]

Thanks for the reply. I'm using a magnetic ballast with a standard 250w MH Bulb from Phillips I think. I just started a new grow from seed using a 20/4 schedule and so far i'm very happy with the results. I've been keeping the tops of the plants no more than 12" away and in most cases probably in the 8-9" range from the bulb underneath a reflector hood. I've been trying to work off of this old chart that has been passed around for ages:

http://i120.photobucket.com/albums/o197/dirt_cheap_goods_2006/mh-chart.jpg

I've quickly come to realize that on my limited number of previous grows I had been keeping my lights wayyy too far away from the canopy. Reading about inverse-square made me want to cry. I'll definitely be upgrading to a 600W HPS for flowering. Anyways - Thanks again for the great information. I've got HIGH hopes for my new grow.

Cool, I will test next week sometime, once I get a new lamp ordered.

 

[WoodElephant]

Getting a B.S. now in plant science, going for at least an M.S. in plant physiology; I am in my mid-thirties. Most of what I know i have taught myself from lots and lots and lots of reading, and talking to those with advanced degrees in plant science; as well as experimenting on my own. I have verified what I learned by using what I learned to grow cannabis...

Very cool! Good luck with the B.S./M.S. (though from what I've seen on here, you don't need luck )

I got my B.S. in Microbiology and I'm starting a PhD program this summer in Micro/Immunology. Not quite the same, but at least it helps me digest your posts

Thanks again for the info you've put on here and other threads. So much for the argument that pot makes you stupid, eh?

I'll get back on topic now, and stop with the tangents

 

[ganjasuiteseat]

t

 

[Sideways]

Hey Spurr- Great info here. Thanks.
I am curious how I would go about calculating the DLI for a grow space based on size/type of light(lumen output), height of light from canopy and size of grow space. I am sure there are other factors, but am strictly talking about DLI- or maybe light saturation?
Based your statements, it would make sense to run the maximum number of lumens ( in the most usable spectrum) almost at the point of light saturation, for the shortest period of time,16 Hours.
This would save your bulb life and energy used (if the added wattage is less than the power used for running the lights for longer periods of time) and would equate to healthier plants, better yields, and quality product?

Do you run your setup like this? Have you quantified any results on any other light regimen?

I was also curious as to your thoughts on plant maturity and the light cycle- Do you think that running the light 24/7 vs. 18/6 vs. 16/8 would have an effect on overall plant maturity? Ie. a better finished product from a plant that has had a number of on/off days in veg as opposed to 24 hour light? It could be quantified in levels of THC and yields of finished product?

Pardon me if I am off base, just trying to get a better grip on how it all works, so that I can try it out and see what works best for me.

 

[Hash Zeppelin]

I have done them all and prefer a 20/4.

 

[Terramoto]

the only difference i notice from giving 24/0 is that the nodes are closer to each other, doesnt 24h makes plant take 2 weeks in 12/12 cycle to start flowering? My plants only show sign of flowering around the 2nd week, and thats what i've been told
Also, my clones dont grow much but its probably because im using CFLs...

 

[Addicted2Grow]

cuz u dont have any timer.

 

[mark lar]

Seriously, 15 pages of dialogue on this matter that's truly rofl.

Thanks Spurr for backing up your point of view with some solid science.

Anyone want to summarize what the end conclusions are ?

More powerful lights and shorter distances to the canopy mean optimal DLI can be achieved within a shorter "day" cycle, which in turn means growers can utilize a shorter photoperiod (18/6, 20/4) while achieving superior growth rates, since plants normally grow fastest during lights out and early morning and their cyclic timings are not interrupted by a protracted photoperiod (24/0) (c.f., calvin cycle, circadian rhythym).

 

[spurr]

Very cool! Good luck with the B.S./M.S. (though from what I've seen on here, you don't need luck )

I got my B.S. in Microbiology and I'm starting a PhD program this summer in Micro/Immunology. Not quite the same, but at least it helps me digest your posts

Nice, good luck with getting your PhD

Thanks again for the info you've put on here and other threads. So much for the argument that pot makes you stupid, eh?

Ha, yea I think that claim is pretty false, at least as a rule.

 

[spurr]

Hey Spurr- Great info here. Thanks.
I am curious how I would go about calculating the DLI for a grow space based on size/type of light(lumen output), height of light from canopy and size of grow space. I am sure there are other factors, but am strictly talking about DLI- or maybe light saturation?

You can't calculate DLI from lumen rating for the lamp with a worthwhile degree of accuracy. If you or anyone else wants to calculate DLI you need to use a quantum sensor for umol/area/second; or better yet, average of 30 or 60 seconds to account for lamp flicker. I have my data logger set to average instantaneous irradiance over 30 seconds but for magnetic ballasts using 60 seconds would be better due to high degree of flicker.

One can buy a Li-cor Li-190SA quantum sensor (~$460) and used Li-cor Li-1000 data logger (~$90) for ~$600 total; a savings of over $600 when buying a used data logger verses buying a new light meter (Li-250A). Buying a new data logger (Li-1400) would be about ~$1,900 with a quantum sensor. The Li-190A and used Li-1000 data logger is the best deal anyone will find at $600 for the newest quantum sensor and an older data logger; that combo is better than a new quantum sensor and new light meter (Li-250A) which costs ~$1,200.

If you want to spend less, you can rent a quantum sensor/light meter combo, the Apogee model I wrote about, from Custom Hydro for $25 a week with a $250 deposit here. However, that quantum sensor has a far less than ideal "quantum response", so the irradiance measurement will not be nearly as accurate as that from the Li-cor quantum sensor I use. Here is the webpage for that Apogee light meter: link

Here is the quantum response from the Apogee quantum sensor, the "defined quantum response" is ideally what the blue line should match. You can see the Apogee under-values blue light, slightly over-values orange-red light and under-values red light:

Here is the quantum response of the Li-cor Li-190SA, the "ideal quantum repose" is the same as the "defined quantum response" from the Apogee image above. Notice how the Li-cor quantum sensor much more closely matches the ideal quantum response than does the Apogee:

Based your statements, it would make sense to run the maximum number of lumens ( in the most usable spectrum) almost at the point of light saturation, for the shortest period of time,16 Hours.
This would save your bulb life and energy used (if the added wattage is less than the power used for running the lights for longer periods of time) and would equate to healthier plants, better yields, and quality product?

Basically, yes. Studies I have read found reduced rate of carbon assimilate from 18 hour and 20 hour days verses 16 hour and 17 hour days. A rather simple way to find out the (near) ideal daylength would be to track the rate of photosynthesis over the whole day when providing near light saturation (i.e., 1,500 umol/area/second). Once the rate of photosynthesis starts to drop (inside a grow room where RH and temp have stayed constant) one can assume the near ideal daylength has been reached for that irradiance. Then one can calculate DLI from the hours of daylength and irradianace per second.

Do you run your setup like this? Have you quantified any results on any other light regimen?

I have recently been using 18 hour days with at least 1,000 umol/area/second but this coming grow I will use higher irradiance because I have a better grow setup than before: 5x5 HydroHut Silver Edition that I plan to line with Orca grow film using a BlockBuster 8" reflector with the Equalizer hot spot diffuser as well as 1 HP water chiller and IceBox to remove heat from HID and act as an AC unit. I also bought a CHHC-4 controller so I can keep Co2 at 1,000 ppm as well as a commercial humidifier and big dehumidifier so I can keep 'Air to Leaf Vapor Pressure Deficit' between 1.15-1.20 kPa (w/canopy temp of ~80'F, average leaf temp of ~78'F and RH of ~60%). That means I will be able to provide more homogeneous irradiance over the whole canopy (and intracanopy from reflectance off walls) and have greater control over VPD as well as Co2, etc. I also bought a Galaxy select-a-watt ballast and Digilux 1000w HPS and MH lamps (both have very high radiance and good SPDs) for the best HID light source (IMO). Using such a setup I will be able to compile more accurate and useful data than a less controlled setup.

I have not yet quantified rate of photosynthesis or carbon assimilate over a day. Once I buy a chlorophyll fluorometer (probably the EARS PPM-300) I will probably track rate of photosynthesis as I described in the example above.

I was also curious as to your thoughts on plant maturity and the light cycle- Do you think that running the light 24/7 vs. 18/6 vs. 16/8 would have an effect on overall plant maturity? Ie. a better finished product from a plant that has had a number of on/off days in veg as opposed to 24 hour light? It could be quantified in levels of THC and yields of finished product?

From my personal experience using 18/6, 20/4 and 24/0, both the former schedules make for more healthy plants than the latter. I have not compared THC between those three schedules, but doing so would be easy with TLC and spot density scanning; or better yet, with HPTLC, HPLC or GC.

Pardon me if I am off base, just trying to get a better grip on how it all works, so that I can try it out and see what works best for me.

You are not off base at all, you seem to have a solid grasp of the topics. Sorry I did not respond sooner, I just noticed your post.

 

[spurr]

Seriously, 15 pages of dialogue on this matter

that's truly rofl.

Thanks Spurr for backing up your point of view with some solid science.

Anyone want to summarize what the end conclusions are

?

More powerful lights and shorter distances to the canopy mean optimal DLI can be achieved within a shorter "day" cycle, which in turn means growers can utilize a shorter photoperiod (18/6, 20/4) while achieving superior growth rates, since plants normally grow fastest during lights out and early morning and their cyclic timings are not interrupted by a protracted photoperiod (24/0) (c.f., calvin cycle, circadian rhythym).

Very well written

 

[macdiesel]

Spurr-I wish you'd post in other threads of relevance besides this one. I respect your opinion, and this thread has been beat to death.

 

[98gsrstock]

basically i screwed up the setting on my timer...plants were getting 16/8 lights\ cycle....they grew to be some very nice bushy indica plants. in flower right now looking amazing...i would say there is no noticable difference when going from 18/6 to 24/0 from my experiences....

 

[b0b_b1tch1n]

I agree, enough talk. There is no need to run side by sides because the jury is already in: plants like cananbis (C3) do better, and grow faster, with a dark cycle assuming enough DLI is provided in the day.

took this from page 19 , i will go back and read the rest of the pages , but i got tired of seeing this over and over , sure the plant grows faster with a dark cycle , but why would you want a stretchy canabis plant ? you get bigger results in the same time frame when vegging 24/7 before switching to 12/12, tested it many many times over the years (growing 1 year shy of 30)

if you want a lanky plant use a dark period , if you want a beefy shorter more productive plant then veg 24/7

 

[spurr]

Hey Bob,

That just isn't the case. You do not get "stretchy" plants with a dark cycle, simply becuase of the dark cycle. When plants stretch it's due to a few main factor such as the difference between day and night temp (i.e., DIF re GA3) and red:far-red ratio intracanopy.

What is the night temp and day temp when you used a dark cycle? It sounds like your night temp was too low relative to your day temp, and if that was the case that is probably why you noticed plants stretch more.

The dark cycle isn't the culprit for what you wrote you noticed, it's something else, most likely it's the temp difference. I wrote a thread about red:far-red ratio in the science subforum where I also described DIF and how to properly control DIF to control strech.

 

[b0b_b1tch1n]

Hey Bob,

That just isn't the case. You do not get "stretchy" plants with a dark cycle, simply becuase of the dark cycle. When plants stretch it's due to a few main factor such as the difference between day and night temp (i.e., DIF re GA3) and red:far-red ratio intracanopy.

What is the night temp and day temp when you used a dark cycle? It sounds like your night temp was too low relative to your day temp, and if that was the case that is probably why you noticed plants stretch more.

The dark cycle isn't the culprit for what you wrote you noticed, it's something else, most likely it's the temp difference. I wrote a thread about red:far-red ratio in the science subforum where I also described DIF and how to properly control DIF to control strech.

my reply is a copy n paste from the other site where you said the same things to me ,,,,,,,

my temps in my veg area only drop about 5 degree when lights out and far from too cold , it hasnt been just latetly ive noticed my plants stretch during lights out , i noticed it many years ago and many times since , im not saying bad amounts of stretch but still is stretch , when growing indoors i prefer a shourt beefy plant with more internodes and tighter spacing

i read all of what you posted and even some of the links , lots of good info , but now im showing you why i prefer 24/7 and after 29 years of trial and error (my own science) ive found 24/7 best for my plants end results , you are prolly right that it isnt actually best FOR the plants but my end results are what im after
i will continue with the tests as i try new strains like i always have

then there is the reasoning of haveing 2 diferent flowering rooms one on and one off switching each 12 hours , way more practical to go 24/7 when i only have one veg room

 

[Dave Coulier]

Bob what type of lighting are your plants under? IME R:FR ratio has the greatest affect on stretch. I can grow short stocky plants when my DIF is even at 15 because I keep them under 6500K GE Starcoat T5's, yet they are on 17/7. Below is a couple of pictures of a Mr. Nice shit clone thats been under 17/7.

Spurr is right that its not the light schedule thats causing lankiness in your plants. Something else is the root of your cause.

 

[b0b_b1tch1n]

Bob what type of lighting are your plants under? IME R:FR ratio has the greatest affect on stretch. I can grow short stocky plants when my DIF is even at 15 because I keep them under 6500K GE Starcoat T5's, yet they are on 17/7. Below is a couple of pictures of a Mr. Nice shit clone thats been under 17/7.

Spurr is right that its not the light schedule thats causing lankiness in your plants. Something else is the root of your cause.

you posted somwhere else about them being your runts (maybe the shit stains in my underwear post), i have an EQ thats about 3 inches tall and bushy when all the other seedlings are 8 inches tall and bushy ,,, we all get runts

as for my lighting ,,, 1200 watts mh
and you think after 29 years of growing and trying many different things that i wouldnt figure out the issue ? as you said "the light schedule thats causing lankiness in your plants. Something else is the root of your cause." NO the light schedule IS the issue , ive proved it many many times

Edit : ahh yes Jonny Rotten you did mention "she's the most compact by far out of all of them" so i guess your theory only stands up for "some" plants

also , you mentioned "lankiness" in my plants in your post here

My plants are not lanky at all , do you know why ?

because i veg 24/7 , only times i got lanky plants was when i vegged 18/6 or 20/4
so tell me again how its some other issue causing it , and prove it ,,,, you cant prove it though because under 24/0 i do not get lanky plants

 

[Dave Coulier]

you posted somwhere else about them being your runts (maybe the shit stains in my underwear post), i have an EQ thats about 3 inches tall and bushy when all the other seedlings are 8 inches tall and bushy ,,, we all get runts

as for my lighting ,,, 1200 watts mh
and you think after 29 years of growing and trying many different things that i wouldnt figure out the issue ? as you said "the light schedule thats causing lankiness in your plants. Something else is the root of your cause." NO the light schedule IS the issue , ive proved it many many times

Edit : ahh yes Jonny Rotten you did mention "she's the most compact by far out of all of them" so i guess your theory only stands up for "some" plants

also , you mentioned "lankiness" in my plants in your post here

My plants are not lanky at all , do you know why ?

because i veg 24/7 , only times i got lanky plants was when i vegged 18/6 or 20/4
so tell me again how its some other issue causing it , and prove it ,,,, you cant prove it though because under 24/0 i do not get lanky plants

Perhaps, I should have chosen a different plant to highlight
, but since you're following my Shit thread, then you will also notice all my other Shit clones are rather short and compact. Only two I would consider a bit "lanky", but they are much more compact than most pictures of plants you'll see in grow logs.

Fertilizer choice(Ammonium based), as well as high perched water tables contribute to stretch as well. Maybe the problem is your bulbs or something else. I dont know without being in your grow room, but short stocky fast growing plants can easily be grown on 17/7. 24/0 is not required to get compact plants.