Makavellian
Member
I read in a post sometime back that plants normally droop when it is almost time for "night", the same way humans get tired after a long day. Is there any truth to this?
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Drooping late in photoperiod?
- Thread starter Makavellian
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my purple creams would do it.. my a-10's would not.. they were together with the same light cycle.. all in 3 gal pots with soil.. my hydro plants, none of them did it.. a-10's might of drooped deep in dark cycle but purp crm drooped up to an hour before.. and no they weren't dry..
CheeseNstomata
Member
mine would if i had any but moreso @ the bottom "K2"
They r clever little fookas
They r clever little fookas
Leaves on the Cannabis plant don't "normally" droop in late light period, even if it's a often occuring phenomenon.
Leaves can droop because of several reasons, such as overwatering, underwatering, heat stress, light saturation, disease, and I've also heard that cold temperatures can make it droop. In general, the drooping is a response to dysfunctioning photosynthesis. During night, the plant also lower the leaves, since it doesn't photosynthesize in absence of light.
After a long day of intense HID lighting, accompanied with high temperatures, the plants can be slightly heat stressed, which is the most probable cause for your drooping leaves, but it could be any of the above mentioned reasons.
Leaves can droop because of several reasons, such as overwatering, underwatering, heat stress, light saturation, disease, and I've also heard that cold temperatures can make it droop. In general, the drooping is a response to dysfunctioning photosynthesis. During night, the plant also lower the leaves, since it doesn't photosynthesize in absence of light.
After a long day of intense HID lighting, accompanied with high temperatures, the plants can be slightly heat stressed, which is the most probable cause for your drooping leaves, but it could be any of the above mentioned reasons.
D
dre86
My outdoor plants always do this, indoor never experienced thatMakavellian said:
well, my temps are about 75 the whole time..not exagerating.. maybe if the probe is in the air right in the light it will read about 79-80. i dont think its light stress.. it was my understanding that all plants have a peak period towards the middle of their light cycle.. they wake up, have a peak, then get tired, then go to sleep.. thats my understnaidng of it..
Frozenguy said:
To understand plants, don't transfer human notions to them. They don't get tired in the same sense as we do, and they don't sleep during the dark period. Their activities simply change (don't forget that you can vegetate your plants under 24/24h of light without any kind of stress if done right). Drooping leaves is a sign that something isn't working right in the plant, like for instance the photosynthetic process. When it's not functioning (or at its full potential), the plant will lower its leaves because it does not need to hold them up like it generally does to absorb the light photons. It's a way to economize energy. Equally, a plant that wants more light will peak its leaves towards the light source, perhaps you've seen your plants point their leaves upwards at times. Also, if you move the light source, the plant will orientate it's leaves towards the light (and grow in the direction of it). This is called the phytochrome response.
A plant that has been basking in strong Sun or HID light for 10-11 hours straight might have reached its full photosynthetic potential. This saturation can depend on various factors, but it boils down to that it cannot absorb more light photons and therefore lower the leaves. In any case, it's not because the plant is getting drowsy.
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Makavellian
Member
Awesome thanks for the good info guys.
Rosy Cheeks said:
ok.. i see that.. thanks
Thats actually pretty interesting.. so your saying that they may droop because they have taken in all the light they can? i mean, that doesn't neccesarily mean something is wrong in my grow room right? what could be adjusted if something is wrong?
Frozenguy said:
Frankly, it's very hard to say based on the little I know of your grow. It could be light saturation, or one of the other reasons mentioned. But if it happens systematically, at the same time of the day (end of the light cycle), it could be it. Light saturation, or the point of diminishing returns as it is also called, is when the plant cannot absorb all the light that hits the leaves in order to photosynthesize it. When it happens, the light photons simply bounce off.
It's difficult to fix a limit for this light saturation point. It is different for plants in different ages and stages (seedlings, clones and young plants are sensitive to strong light, a fully mature flowering plant can take extremely high amounts of light), the quality of the light - or the PAR values - decides if the plant's needs (of the right kind of light) are covered, temperatures and air humidity are crucial factors, the health of the plant also plays a role (a sick plant's metabolism is less efficient, it therefore photosynthesizes less), tropical strains seem to be bigger light hogs than other strains, etc etc.
Outdoors, it is concidered that a bright summerday with direct sunlight is equal to approximately 10 000 foot-candles (A unit of measure of the intensity of light falling on a surface, equal to one lumen per square foot and originally defined with reference to a standardized candle burning at one foot from a given surface). This is what the Cannabis plant needs to grow optimally.
To convert from foot-candle to a lumen/sq. meter, multiply by 10.764.
So, 10 000 X 10.764 = 107,640 lumens.
A 1000w High Pressure Sodium bulb puts out approximately 140.000 lumens, a 1000w Metal Halide puts out approximately 100 000 lumens
A 600w HPS bulb puts out approximately 90 000 lumens
a 400w HPS bulb puts out 50 000 - 60 000 lumens, a MH 30 000 - 40 000 lumens
But that's just the output, or the initial lumens. What counts is how many lumens that reach the plants (measured in lux), because the light output diminishes according to the inverse square law:
http://en.wikipedia.org/wiki/Inverse-square_law
To make it simple; at 30cm (11.8 inches) distance (from the bulb) the plants receive close to the initial lumens. At 60cm (23.6 inches) distance, divide by 4.
Multiple light sources will of course put this inexact rule at an end. The best way to measure how many lux your plants receive is to measure it with a light-meter.
Whatever the case, a 1000w HPS kept at a fair distance represents the approximate equivalent of a bright summer day (with less performant PAR ratings), so you see it's hard to overdose on artificial light. Heat from the HID:s generally become a problem before you reach the aquired amounts (10 000 lumens per square foot being the desired level)
But outdoors, light intensity and temperatures vary during the day, whereas indoors, it tends to be constant from start to finish.
10 000 lumens of outdoor light have better PAR ratings that 10 000 lumens of HPS or MH light:
http://en.wikipedia.org/wiki/Photosynthetically_active_radiation
There are some growers that advocate overkill light, since in theory more than plenty light doesn't harm the plants (it's just a waste of electricity). Although, it presents a big heat problem, and bud exposed to hot, intense HID light have a tendency to be more brittle, and have less taste than outdoor bud, IMO.
G
Guest
I have a similar question, my leaves are drooping on my plants and the new growth seems weak and flimsy and they were transplants 3 days ago, into 5 gal buckets with ff of with a lil bit of dol lime and some worm shit, what could be the cause of this, before the transplant the plants didnt have enough perlite, do you think they might still be getting ajusted to the new soil?
