Blueberry Cookies LED Grow

[trichomehi]

So it's been about 6 months since i've done a diary, i've done 2 crops under these par+ led's, and the results have been very poor compared against concurrent hps grow. The idea of this diary is to see what i'm doing wrong or to confirm that there's a lot of hype about led's. The comparison grow starts in a week and i'll keep them in the same diary (same strain).

The plants go into system at about 2wks old..

   

[seb88]

Those temps seem a bit low if that's lights on, but I guess the lights are dimmed at this stage?

 

How did the yield compare to hps? 

[trichomehi]

Strain in question was barneys farm critical kush under hps 4 plant average 28ozs, led's 16ozs. Another very obvious thing i noticed was the lack of build up on the trimming scissors compared to hps which i had to clean twice for 4 plants, the lack of trichcomes under the led is very noticeable in direct comparison to the hps, this is the point of this dairy to see that comparison. 

                        On yesterday's post i forgot to add the par readings, both lamps are the same height all plants receiving 300-350 umols m2, I'm using a apogee meter, I'm really surprised at the footprint of the light there very little fall away of intensity compared to the hps.

 

[trichomehi]

In comparison to the 4 plants under led, are the four plants under traditional lighting, at this stage that consists of 400 watts mh. The plants are in 2 1mx1mx2m tents, each pair of plants are under 1 traditional lighting system, the plants are in nft systems, each of the 3 tents are in the same room, all exhaust gases are vented away from the room all fresh air vented in through a large window, due to the inherent nature of the light systems environmental differences will occur, for example the environment temps in the led room have had to be raised from 21c to 25c as the plants were showing signs of distress, moving from a warm propagation enviro to a much cooler one. The enviro temp under the trad lights is 27c, boosted by warm conditions outside, this is in both tents.

tent 1

   

tent2

 

All the plants are on the same feed regime, 2ml/lt shogun grow, plus cannazyme. ph 6.1

[trichomehi]

addendum:

plants under trad lights are set at 24hr pattern same as led, plus par meter reading at 300 umols/m2, same as led.

[samhigh]

good luck with the grow, if you haven't tried these their scrumptious

 

look like there ready for take off, cant wait to see the growth of these girls

 

sam

[Jibba jabba]

Alright there @trichomehi

 

Nice start, always good to see a direct comparison grow.

 

Lots of controversy over the leds nowadays with lots of people saying lots of different things.

 

The truth is simple, they are different from hps so will take a bit of getting used to.

 

In your photo I could make out the drivers are meanwell and I’ll presume the leds are Samsung, if so I am sure once you get a few more grows completed with them you’ll be back to massive yields.

 

I don’t want to be sucking eggs or anything but tokenroll does a cracking diary and is very knowledgeable in the field of led.

 

Anyway I have waffles enough.

 

Take it easy. Jj 

[trichomehi]

Thats the whole reason for the diary, to see what i'm doing wrong, someone mentioned leds need a high temp environment for the plants to thrive, but i can't get my head around that.

[Greenls]

The vpd charts are seem to be much more important with led.

You don't get all the IR heat so room temperatures generally need increasing to be more around 28c mark.

 

What size hps lamp? 2x 400w? So 550w of led vs 800w of hps? 

[trichomehi]

interesting, the vpd charts aren't actually saying you need a higher temp its gives a rh guide in relation to temp, in veg it suggests a vpd of 0.8 to 1.1, in my case temps at 21c i need a rh of 60%, funny enough before i added a heater, my enviro was in the correct range. If the room temp is at 28c then to stay within the vpd guide of 0.8 to 1.1 then the humidity needs to be roughly 75%. So to grow successful plants under leds i've got to mimic the conditions of the hps by raising temps plus raising humidity, i've spent last 15yrs getting rid of excess heat which has lowered the humidity and bringing fresh air in enviro, i'm wondering if these led's are more trouble then there worth..

[Greenls]

The 28c is just a guide temp. In full flower hitting that with ~60%rh  seemed to do the trick for me until the heat wave messed everything up

 

Which chart you looking at though. The one I got here suggests 47.5% for 21c?

 

 

[trichomehi]

5 hours ago, Greenls said:

The 28c is just a guide temp. In full flower hitting that with ~60%rh  seemed to do the trick for me until the heat wave messed everything up

 

Which chart you looking at though. The one I got here suggests 47.5% for 21c?

 

 

 Thats the range for vegetation, the lower humidity reading is for flowering, i think..

[trichomehi]

Start of flowering...

Since last post heater has been added to tent, lights switched over to 12/12, intensity levels now at 600 umols/m2, temps at 27-28, humidity low 30's.

 

[Shumroom]

I'm new to VPD(my next/current grow is the first time I'll be trying to achieve the 'ideal environment'), so take everything I say here with a pinch of salt.

 

From what I have read about VPD, and what you have written in your diary.

 

Your plants are 4 weeks old tomorrow (is this from seed or cutting?) I'm assuming seeds as no mention of clones, which you should really use for a true back2back.

 

4 week old plants I would have thought would be a bit lower than you quote, 1.1 seems very high to me for plants this young.

Please correct me if I'm wrong.

 

Are you using a VPD chart generated for LED rather than HPS, as leaf temp which is a part of the VPD calculation will be different under the 2 types of lighting.

 

Do you measure your leaf temp?

 

 

28c and r/h of 33 percent will cause them to over expire, probably cause tip burn and other signs of excess.

 

I'm having the opposite problem in veg atm(signs of deficiency paired with excessively high humidity as I don't have an extractor fan for it, I do intend to draw fresh air in by connecting my bloom-room to my nursery/veg area(to suck the old air out), once the current drying is finished.

I never used to get to this size before moving them into larger space with extraction.

 

At 28C I would aim for 70 to 75 percent r/h

or

At 26C, then 66 to 72 r/h.

 

I've worked this out using a spreadsheet generator from 'Pulse', varying from a 2 degree to zero degree difference between environment and leaf temp and aiming for a VPD of 0.9

 

I hope that either this helps you out,

or,

I get some 'higher' learning on the subject 

 

 

[trichomehi]

On 15/09/2020 at 1:50 AM, Shumroom said:

I'm new to VPD(my next/current grow is the first time I'll be trying to achieve the 'ideal environment'), so take everything I say here with a pinch of salt.

 

From what I have read about VPD, and what you have written in your diary.

 

Your plants are 4 weeks old tomorrow (is this from seed or cutting?) I'm assuming seeds as no mention of clones, which you should really use for a true back2back.

 

4 week old plants I would have thought would be a bit lower than you quote, 1.1 seems very high to me for plants this young.

Please correct me if I'm wrong.

 

Are you using a VPD chart generated for LED rather than HPS, as leaf temp which is a part of the VPD calculation will be different under the 2 types of lighting.

 

Do you measure your leaf temp?

 

 

28c and r/h of 33 percent will cause them to over expire, probably cause tip burn and other signs of excess.

 

I'm having the opposite problem in veg atm(signs of deficiency paired with excessively high humidity as I don't have an extractor fan for it, I do intend to draw fresh air in by connecting my bloom-room to my nursery/veg area(to suck the old air out), once the current drying is finished.

I never used to get to this size before moving them into larger space with extraction.

 

At 28C I would aim for 70 to 75 percent r/h

or

At 26C, then 66 to 72 r/h.

 

I've worked this out using a spreadsheet generator from 'Pulse', varying from a 2 degree to zero degree difference between environment and leaf temp and aiming for a VPD of 0.9

 

I hope that either this helps you out,

or,

I get some 'higher' learning on the subject 

 

 

growing to a perfect vpd is very difficult if you cant exactly control the enviro and all the assoc kit (which i dont or will never have), my "style" of grow is to try to balance the temps against the humidity by simply controlling the extraction of stale air out of tent. The plants go into the main tents after being in a nursery room (250 watt cfl, natural air movement), there usually in there for a couple of weeks from seed ( conditions roughly 26c 70% humidity). The biggest problem i have whether its in led tent or trad lighting tent is the transference shock, going from a high humidity to a much lower humidity, plants always go into a droopy looking stage, they pick up after about 10ish days. As for the quotes about vpd levels thats straight from an internet source, the source was for led's and the one i quote is for vegetation.I am measuring leaf temp directly under lamps plus the room air temp in 3 different positions.This comparison is done just out of interest to see if i'm doing something radically wrong, there are led growers on this forum who claim to have good results from there lights by not having to increase temps, this supposed need for room temps to be 28c to raise leaf temp is completely foreign to me, it's all a learning journey.   

Edited September 16, 2020 by trichomehi