GDD and light dep by crossfade69

crossfade69

crossfade69

Well-Known Member
This is going to be long winded but I think very interesting.So I have been doing some research on why plants harvested in warmer temperature seem superior to those harvested in say the begining of october.Not in yield but in quality.I have been looking and reading many different growers light dep crop threads all over the net and the same thing is said time and time again there june through august harvest turn out better than there full season plants.One in particular has been growing the same cut of sour d for years,he harvestd in may then again in july and then has full season.The may and july plants were grown the same and flowered at the same height,the july plants were twice the size and much stickier smelled better and were much heavier. So why the answer is called GDD growing degree days,a concept used by field growers corn ,squash etc. For years also used for pest control but for now we are interested in the phenology side of things.What is it it is ?Growth stage models predict the time of stages in an organisims development useing developmental thersholds For example corn has been studied for years and its lower thershold is 50 degrees and its upper cap is 86.Simply put growing degree days accumalte anytime the average temp for that day is more than 50 degrees f.Plants need a certain amount of accumated gdd to grow properly and harvest. So if it is 70 degree high for the day and a low of 40 you would have a gdd of accumalation of 5.Simple formula max temp +MIN TEMP divided by 2 -50 =gdd for the day higher the number better the growing day.Any day under a 50 average is not subtracted but ignored from the total.Another example would be say august day we had a low of 65 and a high of 100 which is the benivicial cap for most plants your gdd for the day would be 32gdd a great growing day or harvest day.Say october normal finnishing time for pot ie 55 low 75 high gdd would be 15 not very high so you see where I am going.Light dep crops with a long veg time and harvested in the warmest months june july and august wiil be of superior quality .What do you think?
 
crossfade69 said:
This is going to be long winded but I think very interesting.So I have been doing some research on why plants harvested in warmer temperature seem superior to those harvested in say the begining of october.Not in yield but in quality.I have been looking and reading many different growers light dep crop threads all over the net and the same thing is said time and time again there june through august harvest turn out better than there full season plants.One in particular has been growing the same cut of sour d for years,he harvestd in may then again in july and then has full season.The may and july plants were grown the same and flowered at the same height,the july plants were twice the size and much stickier smelled better and were much heavier. So why the answer is called GDD growing degree days,a concept used by field growers corn ,squash etc. For years also used for pest control but for now we are interested in the phenology side of things.What is it it is ?Growth stage models predict the time of stages in an organisims development useing developmental thersholds For example corn has been studied for years and its lower thershold is 50 degrees and its upper cap is 86.Simply put growing degree days accumalte anytime the average temp for that day is more than 50 degrees f.Plants need a certain amount of accumated gdd to grow properly and harvest. So if it is 70 degree high for the day and a low of 40 you would have a gdd of accumalation of 5.Simple formula max temp +MIN TEMP divided by 2 -50 =gdd for the day higher the number better the growing day.Any day under a 50 average is not subtracted but ignored from the total.Another example would be say august day we had a low of 65 and a high of 100 which is the benivicial cap for most plants your gdd for the day would be 32gdd a great growing day or harvest day.Say october normal finnishing time for pot ie 55 low 75 high gdd would be 15 not very high so you see where I am going.Light dep crops with a long veg time and harvested in the warmest months june july and august wiil be of superior quality .What do you think?
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Very interesting CF. I never knew there was math behind it, I figured it was just stoner hear say.
 
Yeah, I got to see a lot of gear grown all over cali this past year, and the so cal bud just out glistened! Hey on a sidenote cf, any of ur 20 gals put out over 2 units last year? Feel like some of mine are looking comparable in size to urs. These are definitely my biggest I've grown in 20 gals..
 
757 I was only able to havest a small portion from those we had a shit of rain then tons of mold and I was concentrating on the big plants I had at the property but they really looked like they could have pulled two and I bet you will.
 
757growin said:
Yeah, I got to see a lot of gear grown all over cali this past year, and the so cal bud just out glistened! Hey on a sidenote cf, any of ur 20 gals put out over 2 units last year? Feel like some of mine are looking comparable in size to urs. These are definitely my biggest I've grown in 20 gals..
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Yes with this concept it makes sense
 
Boss I was blown away to, it is great info they also use this for insect spraying programs they go by the temperature to tell when bugs will be hatching .They can also take averages from year to year as they have been useing this concept for many years.
 
757 dessert grows would be interesting with the benificial cap being 100 degrees any thing over is not nessisarly benificial as well as anything under fifty ,with that being said it would probaly work good with it being so dry while they are in flower no mold worries or pm .Might not be the best for vegging them as they like more humidity during this stage maybe veg inside creating more humidity then move outside to flower.
 
Can it be sun angle instead of temps?
Sept/Oct the sun is much lower in the sky thus producing more ultra violet rays in the "red" spectrum vs. May/June/July when more of those rays are in the "blue" spectrum. I remember reading growing under light in the "blue" spectrum will more resinous buds, but indoor growers switch from MH to HPS which has more "red" spectrum, so that has me confused. I think they do it to help fool the plant into thinking it's fall, and to mimic the outdoors light spectrums through out its life cycle.
You may want to research that too.
TMB-
 
TREEMAN I love full season natural cycle and I grow indoors also 4k two halides two hps I cant see a differance in the buds at all and they have been useing this for many many years.They use it for planning there corn crops and there squash and every other type of field plant and I did not see anywhere where the spectrum is mentioned of course different humidity levels will come into play as well as other environment factors.But they are doing multiple crops per year and they were only concerned with the gdd accumalted,witch is based off of average daily temps not the light spectrum.Thanks for the post I will do more research on the spectrum have a great weekend
 
I was thinking it was due to light intensity and the uv index being greater during summer months. My plants are frosty as fuck and still have 4 weeks to go on most of them. I love summer buds. I think I will do a light dep every summer if possible.
 
Fresno I am sure that comes into play as well and I bet your stuff is frosty how many weeks left?Light dep is alot of work but it is my future because we have such unpredictable wheather in october,and the end of september.I am confident if all growers had to deal with what we have the last few years as far has crazy amounts of rain super early frost and crazy winds they would be looking into something different.WE had more rain in the last two weeks of september last year than we got all winter and that is not normal for us but nothing is anymore.We had mid thirty temps september 28 it was brutal along with 30 plus mph winds and stupid amounts of rain.The year before indian summer and bud quality was much better I mean much better.The gdd just confirmed what I had thought true for years and I wish I had done lots more light dep mine are looking great and are way ahead on bud development and frost.I had a fellow grower come and take a look and she agreed and was surprised at the speed of deveopment.
 
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