Slow growth since switching to LED

[FriendlyFarmer90]

Yeah I didn't even know that controlled existed I'll check it out, yeah it's more like co2 compatable as you can get a ppfd of 1600 umol if you use all 10 bars, I have 8 in and thinking about it that math doesn't add up, I put the 2 bars back in and gain 60% extra ppfd. You only need to introduce co2 if you plan on utilising more than 1000 ppfd which if you look on the bottom pic I can get a great ppfd of 1000 (co2 not necessary) with 8 bars in at 65cm View attachment 1245752

The controller is pricey but imho worth it, it has function to replicate sunset and sundown etc. Same here on using less bars, mine has six and i used only 4 in my most recent grow and have much less burning and have only had it at 75% in flower. Running it at a lower setting will increase the lifespan of led’s so thats a win too. Hope you figure it out, i do agree your young plants might get too much light, i set mine at 25% and 40cm in veg (60-70 when they are young) hardest part for me is getting the distance and intensity right after flip so i dont get too much stretch or none at all.

 

[FriendlyFarmer90]

The controller is pricey but imho worth it, it has function to replicate sunset and sundown etc. Same here on using less bars, mine has six and i used only 4 in my most recent grow and have much less burning and have only had it at 75% in flower. Running it at a lower setting will increase the lifespan of led’s so thats a win too. Hope you figure it out, i do agree your young plants might get too much light, i set mine at 25% and 40cm in veg (60-70 when they are young) hardest part for me is getting the distance and intensity right after flip so i dont get too much stress or none at all.

Worth to mention i run a 120x120x210 tent. Looking to get a growrilla tent because i need the added height because of flood table.

 

[jguit]

A decent PAR meter in invaluable to an LED grower. Highly recommended.

There's no way you can accurately judge LED intensity by eyeballing it, especially when playing around with the dimmer.

 

[Aqua Man]

I was told led has a more intense light. When I look at the umol chart it has a great ppfd map and with 8 bars in its close to 1000 umol over the canopy, so my thinking is a plant in veg needs 300 to 550 umol so following the lumatek chart 50% power would equate to around 500 umol at 56cm. Right?

Absolutely right

 

[strider26554]

Ill go back and finish reading the original post to see what i can but here is part of the issue.

Those LED ARE MAD powerful…. I do see some lights stress so backing them off is your number 1 concern right now no matter what other contributing factors are involved until we get this sorted. But i can assure you that they will never need to run over 80% and likely much lower.

So you probably notice your plants are staying shorter and an increase in the density and overall leaf surface area… this is because of the spectral difference. Your stretch will be reduced but overall bud weight will be higher and the buds much tighter and denser… this is spectral due to the photo morphology. I can get deeper into that later if you like.

Also under LED because of the spectral difference and photo morphology the plants will benefit and id go so far as to say need more Ca, Mg and K. It changes the structure of the plants and therefore slightly the nutrient ratios desired.

You are 100% right its the light. But it’s all beneficial so long as you don't over do it which 99% of new growers and growers switching from HID do. Its just hard to wrap your head around how powerful these lights actually are.

As @Heywood mentioned they put out over 30% + more photons per watt than the most efficient HID on the market today.

What intensity and height are they currently at?

I am an old school hps and mh grower and im using leds on some of my grows this year and there has been a HUGE and i cannot stress enough, HUGE learning curve. I have learned more about plant structure and nute requirements on the topic of lighting differences from the guys on this site than i ever thought I would.

 

[Aqua Man]

Ok they are currently 18\6 and ye my thinking was if i want them to go up I move the light up so they can stretch to reach it, but I didn't want to do that incase the fact was too little light and therefore would be even more negative impact on them. I'll move them up now.

I managed to speak to a guy for 5 mins from lumatek and he said what people are doing with these lights are... 25% for seedlings 50% for veg, 75% for first half of flower and 100% for the second half of flower with 8 bars in to maximise the fact the plant can take in 1000umol when flowering

But remember what he is wuoting is not taking in genetics and all the other growth factors. The truth is a plant will handle as much light as its limiting factor. I have run plant at 1200+ in flower by running co2 as an example.

Dont go by numbers go by the plants, numbers are a good tool for ballpark.

See the V shape to the upper most leaves and how they are flat a bit lower down… that is a response to light. Those upper leaves are folding to reduce light capture.

Your are foling just a bit to much

 

[Aqua Man]

What your describing is exactly what I've experienced. Small dense plants with huge leaves, I had to remove quite a few insanly large fan leaves that umberellad the whole plant to allow the light to get to all the nodes

Ill post a link on that for you. You dont want to remove to much in veg as the more overall photosyntheses will be lower and thus the energy produced by the plant and whike it may not slow growth you could have more. Airflow is the key but read here.

How To Defoliate Cannabis Plants For Maximum Yields

So let me explain defoliation in a way that will allow you to know how and when to defoliate. This is basic and wont include crop steering methods. You need to get a good base understanding and practice first imo before going all ham on advanced techniques. Reasons for defoliation: 1. Airflow...

www.thcfarmer.com

 

[Weedgrower]

A decent PAR meter in invaluable to an LED grower. Highly recommended.

There's no way you can accurately judge LED intensity by eyeballing it, especially when playing around with the dimmer.

A decent PAR meter in invaluable to an LED grower. Highly recommended.

There's no way you can accurately judge LED intensity by eyeballing it, especially when playing around with the dimmer.

My understanding is par is less accurate than umol I'm really a novice at led lights and it's terminology. So you recommend getting a par meter, how m

But remember what he is wuoting is not taking in genetics and all the other growth factors. The truth is a plant will handle as much light as its limiting factor. I have run plant at 1200+ in flower by running co2 as an example.

Dont go by numbers go by the plants, numbers are a good tool for ballpark.

See the V shape to the upper most leaves and how they are flat a bit lower down… that is a response to light. Those upper leaves are folding to reduce light capture.

Your are foling just a bit to much

What is foling sorry?

 

[Weedgrower]

My understanding is par is less accurate than umol I'm really a novice at led lights and it's terminology. So you recommend getting a par meter, how m

What is foling sorry?

Like removing leaves? I had to because of the size of them and how high they were up, essentially not allowing any light to get to anything more than 2 nodes

 

[FriendlyFarmer90]

My understanding is par is less accurate than umol I'm really a novice at led lights and it's terminology. So you recommend getting a par meter, how m

What is foling sorry?

As far as i understand, PAR = photosynthetic active radiation, umol is a means of expressing PAR

 

[Aqua Man]

My understanding is par is less accurate than umol I'm really a novice at led lights and it's terminology. So you recommend getting a par meter, how m

What is foling sorry?

Its when Aqua fats fingers his keypad lol… sorry brother should say folding like a V a bit to much on the upper most leaves.

Those that know me are used to th writing of my crytic fat fingers combined with a non english speaking, blind, challenged monkey….. what can i say, i have been vlessed with those things

 

[Aqua Man]

As far as i understand, PAR = photosynthetic active radiation, umol is a means of expressing PAR

Yea but par is only 400-700 wavelength so a quantum meter is far more accurate. That said id go based on the charts then adjust based on plant responses

 

[FriendlyFarmer90]

Yea but par is only 400-700 wavelength so a quantum meter is far more accurate. That said id go based on the charts then adjust based on plant responses

Yeah quantum meter is what i meant, price tag is not in my budget so i use the app.

 

[Weedgrower]

Its when Aqua fats fingers his keypad lol… sorry brother should say folding like a V a bit to much on the upper most leaves.

Those that know me are used to th writing of my crytic fat fingers combined with a non english speaking, blind, challenged monkey….. what can i say, i have been vlessed with those things

I'm not sure exactly what you mean by folding like a v

 

[jguit]

My understanding is par is less accurate than umol I'm really a novice at led lights and it's terminology. So you recommend getting a par meter, how m

What is foling sorry?

A PAR meter measures PPFD (µmol/㎡s). As mentioned, a quantum meter would do the trick.

 

[Aqua Man]

I'm not sure exactly what you mean by folding like a v

Ok you see if you were to take a leaf from the middle and lay it on a table the whole leaf would be flat against the table.

Now the upper leaves are folding in the middle upwards and towards eachother. The leaf edges are higger than the middle so it has more of the shape like a taco or V. They fold like tgis to reduce light capture by reducing the exposure if the leaf surface to light.

I can try to pull some pics if my explanation is confusing. Sometimes my thoughts are like trying to translate english into french and i dont soeak french loll

 

[Aqua Man]

A slight V shape on the upper 2-3 nodes shows you are pushing the plants just into some ever so slight light stress and is ideal. Based on the angles you can judge the plants response to light/heat stress.

A byproduct of to much light is that the photons are released as heat by the plant so they kinda go hand in hand but igbore the heat part of the explanation because i dont see the serrations spiking like would be seen in environmental heat stress but not so much seen in stress caused by light.

You can use an IR temp gun to check leaf temps if you like. They are cheap and the most underutilized tool in the Industry. 75-77f actual leaf temp is the most photosynthetically efficient. Under LED you should see leaf temps around 4-5f cooler than room temps depending on transpiration rates.


Im getting way off track so will stop lol. You want a slight V shape to the upper leaves to know your driving the plant to it potential. It’s something you will be able to gauge with a little experience once you start paying attention to it

 

[Lpena93]

Lux meter works well with LEDs
Specially with LEDs

seedlings: 5,000-7,000 lux
Vegetative growth: 15,000-50,000 lux
Flowering: 45,000-65,000 lux
Maximum recommended amount of light:
75,000 lux

 

[Weedgrower]

Ok you see if you were to take a leaf from the middle and lay it on a table the whole leaf would be flat against the table.

Now the upper leaves are folding in the middle upwards and towards eachother. The leaf edges are higger than the middle so it has more of the shape like a taco or V. They fold like tgis to reduce light capture by reducing the exposure if the leaf surface to light.

I can try to pull some pics if my explanation is confusing. Sometimes my thoughts are like trying to translate english into french and i dont soeak french loll

Wow thanks so much for taking the time to explain, I just got some xp points lol. So basically if the leaves go like a they are getting slightly too much light? So higher the light and we should be good? How do you feel about me turning the power up to 75% when I flip in the next week?

 

[Aqua Man]

Wow thanks so much for taking the time to explain, I just got some xp points lol. So basically if the leaves go like a they are getting slightly too much light? So higher the light and we should be good? How do you feel about me turning the power up to 75% when I flip in the next week?

Increase light by the % change in duration. So say 18/6 to 12/12 would be a 33% increase. We are looking to maintain the same DLI (daily light integral) so if your at 600ppfd you would increase to 900ppfd.

But with that said you need to take into account the photosynthetic rates at which the plants can convert photons to energy. So you want to increase say 15% or so and over the next week or 2 up to the full 33% while paying attention to the plants.

Remember a slight V is desirable but not so much as to induce too much stress. After 1 grow paying attention you should have it nailed