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Grow QuestionsI’m looking to get max PAR value(950) on my plan...

I’m looking to get max PAR value(950) on my plan...

SirDilltonstarted grow question 5 years ago

I’m looking to get max PAR value(950) on my plants during flowering. My lights came with a grid that isn’t super specific. Question what are some very first signs of too much light for your plants And should I keep pushing the limit inch by inch to try and achieve maximum light?

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Week 9

Techniques. Defoliation

Philindicusanswered grow question 5 years ago

Great some one else is using a PAR meter. The first sign of the lights being too intense is a bit of canoeing or upturned leaf blades or tips curling up ,slightly folding leaf blades signalling light stress. You may also notice some discoloration or yellowing paling of the leaves closest too the lights if she's blooming watch out for the white pistils browning prematurely. Each strain can differ in terms of how much light intensity it can handle. So since your growing photo periods running your lights 12 hrs a day in bloom you can run them at a fairly high intensity level compared to running them 18-20 hrs while in veg. You need to use a DLI ( Daily Light Intensity) calculator. https://www.waveformlighting.com/horticulture/daily-light-integral-dli-calculator This will help you calculate how much light your plants are receiving daily in Moles per day. https://www.progrowtech.com/2019/05/what-is-daily-light-integral-and-how-does-it-affect-your-crop/ From my understanding your goal is to get into the 39 moles per day range by mid bloom when buds require the highest light intensity. Then as things progress through late bloom ripening stage start decreasing the intensity. I'm currently using the same technique but i'm growing autos running my lights 20 hrs a day. My top Par reading during mid bloom will be in the 650-750 range. If I go higher I will have leaf burn for sure. Since you are running 12 hrs a day you should be able to run your a bit higher using the DLI calculator to estimate how high you need to go. I'm not going to lie so increase the Par gradually a 100-150 umoles until your comfortable with the distance. At 12 hrs a day running 1000 umoles your DLI is 43.20 so your in a good place. if you see signs of stress drop it down to 850-900 it will put you in the 39 DLI range. Hope this helps you need to do bit of experimenting there no way around it.👍

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DankGardeneranswered grow question 5 years ago

Sometimes the first sign a plant is getting too much light is all the leaves start pointing up or “praying”, like this (though sometimes you don’t see any symptoms until the yellowing starts) Example of a cannabis plant that is getting too high levels of light so all the leaves are pointing up With light burn, often the inside veins stay green. Yellow leaves won’t fall off or be plucked off easily, unlike a nitrogen deficiency where leaves fall off on their own. Example of cannabis symptoms caused by light burn. Yellowing top leaves under the grow lights, and the leaf margins often stay great. With light burn, leaves may turn red instead of yellow. The leaves closest to the light may appear much more pale than the rest of the plant, and tips may turn yellow. Light stress or light burn cause cause the edges of cannabis leaves to turn up and tips to turn yellowAnother example of yellow tips from light burn Light stress has caused the edges of these leaves to turn up and the tips to turn yellow. If you see this, move your grow light up at least a few inches! Sometimes light burn causes edges of leaves to turn up. If it goes on a long time, the leaves also start to become crispy and can even break off if you try to bend them These leaves are so light stressed that the edges have turned up and the leaves have become crispy You may noticed just the tallest colas getting droopy, which is sometimes a sign the light is too intense (though it could also be caused by root problems or over/under watering)

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OutForRealanswered grow question 5 years ago

You can see 2 kind of signs when light is too close : 1/ leaves close from light are burning 2/ leaves/buds too close from light are bleaching ( apex chlorosis ) . Honestly I don't know if you can wait to see the 1st signs because these issues are very quick to develop ( a day or 2 ). You can try to push the limit but ... you need a limit to your limit Haha , for example a 600w hps with cooltube will need 30 cm of distance minimum , under that minimal value you'll have issue

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