Jesus christ... has anyone reliably solved the issues of weak growth in early veg under LED? What's the answer????

Honestly I'm thinking at this point to just get myself a t5 fluoro and go back to doing it old school.
In all my years growing, I just put plants into coir, fed them 1.0ec of a base feed, and stuck the fluorescent light on them and watched them boom. two weeks and a pot up later and I'm almost ready to flip...

But under LED there seem to be so many fuckin variables that I'm really feeling quite demoralised by it. I feel like a new grower again trying to figure it out, and I'm far from it. Brought the temps and humidity up, all the usual fixes which have sometimes worked in the past

Is it possible that the spectrum of the Bridgelux gen 3, 3000k whites is causing the issues in the first place? Or is the high ppfd demanding a higher strength feed or some co2?

Is anyone finding problems using similar lights?

Thanks ahead of time people

5000-6500k whites would probably veg quicker as one varible to change

Whats your space and LED setup exactly..?

Chronikool said:

5000-6500k whites would probably veg quicker as one varible to change

Whats your space and LED setup exactly..?

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Well, my space is either a tent downstairs, or the attic, both of which are in controllable environments, so I can raise or lower the temps and RH as needed. My feed strength of canna A/B is around 1.4... I added a bit of epsoms and that seemed to perk them up, but not to the point where they're at that full vigour that I want to see. Nowhere close... just ambling along..

So a 5m x 5m tent with 2w of LED..?

What we got here yo..?

Chronikool said:

5000-6500k whites would probably veg quicker as one varible to change

Whats your space and LED setup exactly..?

Click to expand...

More red – ie 3000K – will veg quicker and will drive all stages of growth faster. The only advatage cool white light with lots of blue in it has is in keeping internodal length a bit shorter, but that can be offset by UVA at the other end of a red spectrum (just like sunlight).

DukeFluke said:

Well, my space is either a tent downstairs, or the attic, both of which are in controllable environments, so I can raise or lower the temps and RH as needed. My feed strength of canna A/B is around 1.4... I added a bit of epsoms and that seemed to perk them up, but not to the point where they're at that full vigour that I want to see. Nowhere close... just ambling along..

Click to expand...

EC 1-1.4 is way too low. I'm feeding my plants in veg right now at EC 2.4.

You don't say what the actual problems with your plants are, so we can only guess, but my guess is you need to feed them more. They also (especially in coco) need a little more Ca, Mg and N due to lower transpiration. Canna is usually pretty good, as the base nutrient has more calcium and magnesium than other blends, but you would be better off using a Cal-Mag supplment than just epsom salts as nearly all Cal-Mag supplments have extra nitrogen which helps with magnesium uptake. You can also keep your pH a little higher in veg (around pH5.8-6.3) to facilitate calcium uptake.

Here's one week of veg under a 3000K LED (smaller seedlings)


Here's two weeks

DukeFluke said:

Brought the temps and humidity up, all the usual fixes which have sometimes worked in the past

Click to expand...

What are your environmental conditions?
Leaf Temp?
RH?
Lux/PPFD?
How young are these plants?
Number of nodes?
Size of pot/container?

Are the plants drinking what you give them, or is the media staying moist longer than you’re used to?
Your EC sounds just fine depending the size of the plants, but what Is your media PH?

Many people new to LED’s have a difficult time getting their environment dialed in because LED’s create a lot of visible light, but not a lot of directed heat in the form of infrared. Most people will need to make environmental corrections under LED to get your plants into a proper VPD range, compared to “traditional” lighting sources. This will get your plants drinking, transpiring, and growing.

CO2 will help the plants breathe a bit easier, but won’t fix underlying environmental issues.

Stronger feed may help, but it may not if your other conditions are not in range. It can even be detrimental if your plants aren’t drinking much and could even lead to mineral lockout. Usually a stronger feed is only necessary when the environment is dialed, plants are growing strongly/rapidly, and EC is the limiting factor. I would check every other factor first (including coco PH) before increasing your feed strength.

I’ve had great luck in veg with leaf temps 80-85F, RH 60%+ 400-600 PPFD. I’ve personally grown in Canna Coco with JR Peters 321 as well as living soil under these conditions with thriving healthy plants. Hope this helps.

its probably a fault on your side.i never had problem with slow growth with leds.maybe you are watering them too much.you have to remember old hps generated a shit tone of heat that would accelerate your soil drying.

Post some pics or describe in detail how they look as well as temps, rh, light levels.. if you don't have a light meter watts per square foot will do.

Also how many hours lights on are you running at?

In my opinion it's lack of radiant heat combined with high ppfd.

I still veg with MH or CMH because tweaking my environment any further would require more work and electricity than seems worth it and I have separate veg and flower spaces.

But a couple of things that helped while vegging with LED.
Much higher air temp (raising leaf surface temp) 84f
Less hours of light. 16-18h no more
Much less ppfd. 20-25% of what I'd flower with.

It's an odd thing that some people seem to struggle with while others defy all logic..

For example @Moflow manages great growth in veg , which I think he attributes to root temps.

T5 for the win.

These last two years I've stopped using the propane furnace after having a wood stove installed. Since then, it's probably 10 degrees cooler on the average in the bedrooms where I have my tents. The ladies are absolutely not digging LEDs during the winter anymore. Being in AZ, I was always worried about my tents being too hot. Now having to sweat the cold also is a whole new experience for me.

MickFoster said:

T5 for the win.

Click to expand...

Hahahahahahahahaha!

Ah, I needed a good laugh. I haven't used T5s since 2001.

Do any of you guys remember when all the HPS growers back in the day used to say "LEDs are only good for veg!"?

Now they're saying LED's not even good for that. And yet . . .

It's really not that hard. Once you wrap your head around the fact that LED produces more light and less heat – and therefore ECs need to be higher alround – you are half-way there. Maintain the correct pH (around 6 in veg +/- 0.3), ensure you have the correct nutrient for growing in Coco (more Ca, Mg, N), and always water until you have 10-20% runoff (self-flush), and you usually can't go wrong.

Why higher EC? Two reasons: better quality light = faster growth = more nutrient (duh!); less heat = less transpiration at the leaf surface and less evaporation from the pot = higher nutrient concentration.

You'll get a million suggestions of what to do, but as everyeone here has already pointed out, you haven't shown us any pix or described what the problem is, so no-one can give you a definitive answer until you do.

DukeFluke said:

Honestly I'm thinking at this point to just get myself a t5 fluoro and go back to doing it old school.
In all my years growing, I just put plants into coir, fed them 1.0ec of a base feed, and stuck the fluorescent light on them and watched them boom. two weeks and a pot up later and I'm almost ready to flip...

But under LED there seem to be so many fuckin variables that I'm really feeling quite demoralised by it. I feel like a new grower again trying to figure it out, and I'm far from it. Brought the temps and humidity up, all the usual fixes which have sometimes worked in the past

Is it possible that the spectrum of the Bridgelux gen 3, 3000k whites is causing the issues in the first place? Or is the high ppfd demanding a higher strength feed or some co2?

Is anyone finding problems using similar lights?

Thanks ahead of time people

Click to expand...

Hey duke. A few details:
Seeds or clones? Our clones are quite light shy but seedlings seems easier. 3000k 80cri yes it can veg fine but around 4000k it will veg better. So no, this is not the spectrum its how youre adapting to it.
You brought up temps and rh, where are they? Im pretty sure you were adviced on vpd already; what tool are you using? Vpdchart.com is a good resource, it lets you set separate temps for leaf and ambient. If youre already in the zone then suspect insufficient nute regime; check ec/ph in and run off to orient yourself.



CO2: maybe not your friend in veg; co2 works against transpiration; more co2 plant is drinking less.

This would be so much easier for both people trying to help as yourself if you added pics. Im pretty sure you never added pics last time you asked about this.

You could also try to add a little radiant heat in the grow, you could try a 20-40w incandescent; even a few with various wattage to see if you like the growth.
Or adding a little mono wattage using blue/violet; anything around 395-430nm for better blue coverage and increased transpiration on tap.

These issues are usually down to transpiration, lack of heat to keep up with metabolism and aimply pushing to hard with the light on a plant thats not ready for it. For transpiration most people just look to vpd but other things also factor in; co2 and amount of blue and general light intensity

Thanks for all the replies, I appreciate it.

Prawn Connery said:

More red – ie 3000K – will veg quicker and will drive all stages of growth faster. The only advatage cool white light with lots of blue in it has is in keeping internodal length a bit shorter, but that can be offset by UVA at the other end of a red spectrum (just like sunlight).

EC 1-1.4 is way too low. I'm feeding my plants in veg right now at EC 2.4.

Click to expand...

From what age are you feeding at that strength? And, how different is that from when you were under HID?

Did you have issues trying to feed at the same strength you did using the old halides?

This might be where I'm going wrong.

Prawn Connery said:

You don't say what the actual problems with your plants are, so we can only guess

Click to expand...

Slow growth, lack of vigour, spindly stems, some interveinal chlorosis, and the leaves curling down away from the light rather than praying up for it. Generally slow shitty plants.

Prawn Connery said:

Here's two weeks
View attachment 5349208

Click to expand...

Nice. So what's your environment setup, ie temps/Rh/light distance etc

Thanks man

cdgmoney250 said:

What are your environmental conditions?
Leaf Temp? About 28c/82f
RH? 60% give or take
Lux/PPFD? About 500 ppfd
How young are these plants? They're about 5 weeks from clone, should be trees by now
Size of pot/container? 5L

Click to expand...

cdgmoney250 said:

Are the plants drinking what you give them, or is the media staying moist longer than you’re used to?
Your EC sounds just fine depending the size of the plants, but what Is your media PH?

Click to expand...

It's staying wet a lot longer tbh, but this doesn't seem to be an issue once they get fully going. It's this initial struggle that really frustrates me. I need consistency and I'm thinking that there's something I keep forgetting to do, from grow to grow, because I don't have a new blueprint so to speak of how to grow under LED.

Rocket Soul said:

Hey duke. A few details:
Seeds or clones?

Click to expand...

How's things bud

Clones my man

So no, this is not the spectrum its how youre adapting to it.

I'm sure it's my own fault, I'm not blaming LED, I'm just wondering if there's things that can mitigate the issues is all.

Rocket Soul said:

If youre already in the zone then suspect insufficient nute regime; check ec/ph in and run off to orient yourself.

Click to expand...

What strength of feed are you finding is best under led from seed onwards? and how is it made up?

Rocket Soul said:

Or adding a little mono wattage using blue/violet; anything around 395-430nm for better blue coverage and increased transpiration on tap.

Click to expand...

You think the 395-430 would help with transpiration?

Rocket Soul said:

These issues are usually down to transpiration, lack of heat to keep up with metabolism and aimply pushing to hard with the light on a plant thats not ready for it. For transpiration most people just look to vpd but other things also factor in; co2 and amount of blue and general light intensity

Click to expand...

I'm thinking it's a combination of this and the feed strength thing. Need to pin it down... badly

DukeFluke said:

How's things bud

Clones my man

So no, this is not the spectrum its how youre adapting to it.

I'm sure it's my own fault, I'm not blaming LED, I'm just wondering if there's things that can mitigate the issues is all.



What strength of feed are you finding is best under led from seed onwards? and how is it made up?


You think the 395-430 would help with transpiration?



I'm thinking it's a combination of this and the feed strength thing. Need to pin it down... badly

Click to expand...

Were usually at around 1.5ec in flower, lower in veg obviously. Checking ec in and run off regularly. If theres is salt build up in the run off then back off. Canna nutes full line.

Sub 430nm blues and violets help with transpiration. I dont know if theres specific work on cannabis but yes on other plans , try googling stomata aperture action spectrum, it will take you to papers and graphs. Also these deeper blues seem to work another chlorophyll as well. Ive seen people deal with the so called led deficiency just adding more blue. Doesnt have to be 400ish nm.

Still no info on your environment or pics of plants? Whats your minimum temps and light levels like?

Not sure if the grow i consult for is the right place to draw from, we deliberately slow down our veg for our clone game to work. Some of the plants have been months in veg right now.

Edit seems like mag is the problem, ive heard people improve this by using slightly higher ph, like 6.3ish, sometimes in every other watering

I had a ton of problems switching to led for vegging, in hindsight it needed higher temps, higher ec and gradually increased intensity.
Due to the temp issues i use t5s most of the year, in summer I sometimes swap to led if it's exceptionally warm.

Imo calmag regularly gets recommended when it's really too low a ec.

My tap water doesn't trigger my truncheon and I've never needed calmag.

A picture would help us to help you.

I use insect frass and liquid silica. It makes super sturdy stems.

Star Dog is right just increase total E.C. In coco you may need to go high until you start multifeeding. 1.8-2EC for a few fertigations and then go down to 1.5 and once you start multifeeding per day you may only need 1 E.C.