Switched to LED, now plants are suffering

[GoatCheese]

I recently switched to LED from HPS/MH Blue. Only thing that changed is that I need to water one day sooner now. I used to water every 5 days now its very 4 days. In a few photos the plants look thirsty to me. After being 100% sure you're not in a over watering situation; I'd say start watering one day sooner.

Under modern leds plants may look thirsty with drooping leaves even if you’d have watered them yesterday if your leds are much too close to the canopy or you’re running your lights with way too much wattage. You will start seeing leaves drooping in 5-10 minutes if you’ll lower your lights to be too close to your plants or you’ll start using way too much wattage.

..First the leaves start loosing their waxy shine and go pale and if it gets worse they will star pointing down like they would be in cold, dry and windy environment.


The photos show clear, usual signs of “led light symptoms” which are caused by the plant tissue getting dehydrated under heat radiation.= Leaves have lost their waxy shine and have developed a matter look – when it gets worse you will see leaves turning pale, then yellow – then yellow with brown spots. The brown spots are basically nute burn damage cause the EC in the leaf tissue has gone up when the moisture in the leaf went out.

Because it’s a dehydration problem plants grown in coco or hydro style will handle the led heat radiation better than soil grown plants, cause there is naturally more moisture in the plant tissue with hydro/coco plants.

 

[f-e]

Is pro mix soil? I thought people said it was peat based. A pH of 6.5 might be too high.

The phone app pic says 35% RH.

Half the light. That will stop them burning out. The lower extract needed will increase RH. In turn, they will drink more, getting the calcium they need. Then you might want to look at how much calcium is a good thing.

Less light, more RH. Then you have an environment they can live it. Next you can look at their diet. Right now, their diet isn't relevant.

Beside RH, Temperature itself isn't that important. Unless it was stupidly cold or hot, Just extract to get the right RH

 

[Creeperpark]

I went back to a 400w HPS from LEDs when I started a new grow, and I noticed water moves faster. That is a big advantage because If the plants are moving a lot of water it's also moving a lot of nutrients.

 

[Creeperpark]

Is pro mix soil? I thought people said it was peat based. A pH of 6.5 might be too high.

The phone app pic says 35% RH.

Half the light. That will stop them burning out. The lower extract needed will increase RH. In turn, they will drink more, getting the calcium they need. Then you might want to look at how much calcium is a good thing.

Less light, more RH. Then you have an environment they can live it. Next you can look at their diet. Right now, their diet isn't relevant.

Beside RH, Temperature itself isn't that important. Unless it was stupidly cold or hot, Just extract to get the right RH

Pro Mix HP and BX are peat-based soil-less mixes that have to be fed.

 

[KiefRichards]

This is very very good thread! Now i add 1/8 teaspoon epsom salt my 1,5 litres bottles i try keeps my girls happy. Bio Bizz nutes grow 1ml bloom 2ml now 10 days 12/12
I add first time some dolomite Ca in my local soil and looking much better than last winter run. TSL2000 and TSW2000 in my tent, thank u vey much Mars HYdroand aND IcMag

 

[Three Berries]

I've found for me if the VPD is being handled well by cycling at a certain RH then the plants are transpiring well. This will probably change with summer though at least for the flowering tent.

 

[f-e]

Pro Mix HP and BX are peat-based soil-less mixes that have to be fed.

So 5.8 ?

 

[stiff]

I would also go with a ph between 5.8 and 6.1.
In fact its what I do on coco/perlite.
And yes.. I use lots of calmag and I'm using marshydro sp6500, ts3000 and ts1000.
But I'm also wondering why noone suggests to check your tapwater quality at your suppliers homepage. Because that's what your fertiliser scheme should be based on.
The roots of all evil...

I would check the water quality report and see how much Ca and Mg is already given.
Lets say you have 50mg/L of Ca already in the tapwater, that should be perfect for seedlings, but a full flowering plant under 350w LED would want more like 150mg/L.

Or if your having the opposite issue,that you have too much Ca,go and get a RO unit and set it back to zero (almost) and start from scratch.

The ratio for Ca:Mg should be about 3:1. @Three Berries said he even goes up to 5:1 in flower. I personally only do the 3:1 and I'm happy.
Rule of thumb:
-Seedlings 50mg of Ca/L
-Young Cuttings 75mg of Ca/L
-end of veg 100-150mg of Ca/L
-in full flower 150-250mg of Ca/L

That might sound complicated,but just upload your water quality report here and someone might help you out.
With that knowledge above, i only needed to figure out how much of Ca is in my Calmag agent and now im just calculating what i need. Of course always look at the plants before overfeeding, but my calmag I give with every watering despite the othee nutes

I hope that helps

 

[Creeperpark]

So 5.8 ?

No, 5.8 pH can burn the tips of the leaves. I always keep the pH above 6 and never below that. I have found that 6.2 works well and so that's my target water pH. With Pro-mix there's nutrient absorption between 6 to 7 pH range.

 

[f-e]

Bronze tips from the reduced P ?

I have played in Canna Terra a few times. Some say it's peat, other say it's bark. Knowing how Canna went after coco as a waste product, Bark seems likely.
You feed it like hydro. Every time at 5.8 and it's not designed for use without feed. However plants can tick over on it, if you pH around 6.5
This is interesting, as without feed you can work it at 6.5 then as you introduce feed you have to lower pH to make it properly available. It's like running soil and hydro together. The more you feed, the lower the pH you need as you move from a soil to a hydro grow.
I have heard people talk about the pro-mix in both contexts. Also how they treat the types differently.

From their site

PRO-MIX HP is formulated in a pH range of 5.2-6.2. Once product is opened, crops planted and watered, limestone is activated and pH will reach 5.8-6.2 within 7-10 days.

I would feed that about 5.5 as I do Terra. Though I have never used the substrate or feed, so it's not advice. It's just how I would approach it. I often run a low pH though. I think it's my taps carbonate levels that like it.

 

[Creeperpark]

Pro-mix is a greenhouse peat-based substrate, and there are plenty of plants that have recommendations below 6.2 pH when using it. Snapdragon, Calibrachoa, Petunia
New Guinea Impatiens, Blueberries, Bracteantha, Diascia, Plectranthus, Sanvitalia, Verbena and Azalia's, and Rhododeniums all require a pH below 6. I thought the same thing, that 5.8 pH with Promix was best but I ran into a lot of problems. Now everything is above 6 pH with every grow.

 

[Douglas.Curtis]

KNF, water soluble calcium and a pinch of epsom salt is all you really need.

You have plenty of nitrogen already and only need calcium and magnesium, treat cal/mag like a leper and leave it on the shelf. The sulfur in the epsom will also boost your terpene production. When the leaves get puffy looking in flower you need to use less calcium.

 

[TPFTFW]

You have doubled your light.
What space are you in. I can calculate a rough PPFD from the light output and space it's spread over. I need it in metric though.

I have no doubt you need to half your light before doing anything else. The math is just to prove it. Half the light, look at RH.

While that will fix short term issues, I think it’s be more appropriate to figure out what’s needed to run them fully, I had my 640w LED’s like 3ft away and plants were insanely happy, now I have my 840w (same light spectrum etc) about a foot away and my 640’s even less

 

[GoatCheese]

While that will fix short term issues, I think it’s be more appropriate to figure out what’s needed to run them fully, I had my 640w LED’s like 3ft away and plants were insanely happy, now I have my 840w (same light spectrum etc) about a foot away and my 640’s even less

What did you change to achieve that? I’m sure we’re all interested to know.

Do you have CO2 running? Are you a soil or hydro/coco grower? nutrient strenght?

Cheers.

 

[TPFTFW]

What did you change to achieve that? I’m sure we’re all interested to know.

Do you have CO2 running? Are you a soil or hydro/coco grower? nutrient strenght?

Cheers.

Just epsom foliars like I said in first post
1/4 tsp a gallon,
In flower I’d recommend going 2x the heavy dose stated for your ca/mg additive
I’m feeding insane amounts but that’s only because sour diesel is a hoss, currently doing 3x the recommended heaviest dose

 

[f-e]

While that will fix short term issues, I think it’s be more appropriate to figure out what’s needed to run them fully, I had my 640w LED’s like 3ft away and plants were insanely happy, now I have my 840w (same light spectrum etc) about a foot away and my 640’s even less

Insanely happy would be a good place to start. Then like I guess you did, advance in increments until it's right up.

Without knowing how much space either of you have, or how big the light unit is with those distances, ppfd is a mystery. All I know is 1000w of sodium is usually swapped for something like your 640w. Not 1500w. Which overshadows 840, until we have an idea of the space being covered in each example.

 

[tdlf!]

Hi, im sure its been mentioned but definitely get the RH to 65% mark.
If the environment is spot on you may find running a slightly heavier fertilizer program helps

 

[Mattbho]

I love finishing my hps runs under led . I packs on the frost last few weeks and they retain more terps . From the cooler Temps I imagine

 

[Three Berries]

Hi, im sure its been mentioned but definitely get the RH to 65% mark.
If the environment is spot on you may find running a slightly heavier fertilizer program helps

My heavy feeding and strong LEDs cause calcium issues which could be fixed as long as they were growing. Once the stretch was done mine quickly got worse and the Ca didn't help.

A flush got +4400 ppm and 5.9 pH out of the first gallon.

But as long as they are in veg the LEDs, heavy nutes with high CO2 can be mitigated by CaCl2, or so it seems as this is still a work in progress.

My oldest flower which has been the lead test plant, has gone to what looks like a potassium issue but just some burnt edges, probably lockout by Ca and low pH..

Also had a younger one in veg that has not been responding well. When I did the first transplant it had a low pH but I didn't think much of it being just the dixie cup. But it has continued. I did another flush yesterday on it and got the run off up to 6.4.

It already looks better though the new growth is much lighter green.

My yard looks lovely from all the waste water nutes.

 

[FletchF.Fletch]

2x Cal/Mag recommended plus 3x maximum recommended fertilizer dose? 2 teaspoons Cal/Mag plus 6 teaspoons of Maxibloom would have an ec off the charts bro.