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Reducing lighting late in flower ?

G

Guest

Does anyone reduce their lighting a bit in the last week or two of flower to make plants think its more like end of fall ? I kind of thought about it and didnt know.
 

2011rex87

Member
That depends on a few things I guess. You should test and compare results. You may find that you get higher yield if you maintain your lights at regular output. On the other hand, you may find you have higher quality if you gradually reduce the light hours or even the intensity of light. Some growers swear that leaving their plants in darkness for a day or two before harvest causes their buds to produce extra resin.

I personally do not reduce the light output or hours of light in my gardens. I do understand the reasoning behind doing it though, because in nature you could experience a reduction in overall light hours and intensity towards the end of flower. For example, for most of continental USA, if your plants began flowering around October and finished early December, you would have a diminishing number of day light hours. This does not mean that human intervention cannot produce more yield when growing indoors. What do you think? If you absolutely need the flower/product and cannot afford a reduction in yields, is it worth the gamble? If so, how much will you reduce? 12 down to 11 down to 10?
 
G

Guest

I don t reduce duration but intensity.
For exemple, I swith 400w to 300 or 250.

I was thinking a bit of both. Reducing lighting time 30-40 min a week last two weeks and 5-10% light level as well. Have no experience with doing it.
 

2011rex87

Member
Some growers will use a PAR meter to "ramp up and down" as the previous poster said. You can use whatever method you would like, but the point is.. You want to gradually increase the amount of light intensity your plants get from seed or clone at 200 par to week 2 at 400 par then maybe up again in week 4 to 600 par then again at 6 up to 800 par and maybe dial down from week 7 to 8 to 9 finally ending with perhaps 10 hours of light at only 600 par or less. Also remember that the wavelength of light changes as the Sunlight is filtered through more atmosphere when in fall versus when the Sun is overhead in summer. So that's why summer is blue light and fall is red light. Same as a red or pink sunset.. The sunlight is being filtered through more atmosphere before it hits your eyes/the plants. So if you were tweaking things out to emulate nature inside, you would accommodate these changes. That said, trace your strain back to it's landrace to see where it's grown and what the environment is like there.. You may test that strain with matching patterns in light hours and intensity. For example a strain grown in South America may thrive at different lighting requirements than a strain grown in Asia. Notice that most growers use MH in veg because the light is dominated by blue wavelength and then in flower switch to HPS because that is dominated by yellow and red and orange.
 

St. Phatty

Active member
I think it works well to move the plants off to the side, so they're further away from the light. Like you said, late in flower.

Patience is important to letting the plant completely do its THC thing (or seed formation thing). But the space right under the light is premium space, especially if you have some plants in veg waiting for 12/12.

From a "production point of view", sometimes you HAVE to move the plants with the best seats off to the side after 7 or 8 weeks.
 

Shmavis

Being-in-the-world
I have done it with both duration and intensity, as well as each individually, and I think it’s a good idea if running a homogeneous garden. Otherwise it’s kind of difficult and possibly counterproductive in a multi-strain garden or perpetual flowering room. In those cases it’s best, like St. Phatty says, to move individuals off to the side. Even into a shadowed area.
 

Phaeton

Speed of Dark
Veteran
Running a perpetual does not allow for weekly time changes.
However, when circumstances mandate, a plant may be moved into the fully dark lung room a week before being ready to trim.

This does not seem to improve yield over having 12/12 the remaining week but is better than trimming a week early.
A lot better.
 

Easy7

Active member
Veteran
There is no real purpose in cutting back light, duration or intensity in the heaviest building period of normal flowering plants.

There is a point to doing that with long flowering narrow leaf. They may never ripen otherwise.

As always it's growers choice. It will speed up ripening but cut back on weight and density during a vital period. Narrow leaf long flowering already built up so much, can't figure it hurts much.
 

h.h.

Active member
Veteran
There is no real purpose in cutting back light, duration or intensity in the heaviest building period of normal flowering plants.

There is a point to doing that with long flowering narrow leaf. They may never ripen otherwise.

As always it's growers choice. It will speed up ripening but cut back on weight and density during a vital period. Narrow leaf long flowering already built up so much, can't figure it hurts much.

I've suspected as much with the "auto flowers".
https://www.royalqueenseeds.com/blog-the-perfect-light-schedules-for-autoflowering-cannabis-n319
 
X

xavier7995

I have done it with both duration and intensity, as well as each individually, and I think it’s a good idea if running a homogeneous garden. Otherwise it’s kind of difficult and possibly counterproductive in a multi-strain garden or perpetual flowering room. In those cases it’s best, like St. Phatty says, to move individuals off to the side. Even into a shadowed area.

That's what I have found as well. It is greatly beneficial to shorten the lights on schedule for stuff that would normally go 12+ weeks, not really much benefit on 8 week stuff (it hurt yields actually). What I wind up doing is running standard 12/12 till I chop the early finishers and then dial it down to 11/13 or so to finish out the rest. I really need to set up another room/area as the sativas do great under 11/13 for the duration of flower.
 
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