Lighting Help

Hey guys,

I’ve had to put all my plants outside because no matter what I did the light intensity seemed too strong for them. The light I’m using is a 1500 watt full spectrum. I’ve included the PAR values in the images below.

No matter what I did, on two separate occasions, my plants showed signs of too much light. Their leafs were browning, spotting, stems turning red, leafs curling in. I raised the light to the maximum height of the tent and they seemed to recover - the red even dissipated but as they grew the red stems came back and the leafs turned down and in again. I’ve had to put them outside (which was the original goal - to veg indoors and bloom outdoors) but I’m concerned when summer is over I won’t be able to complete a full grow indoors. Can anyone help me figure this out? I can’t understand why a 1500 watt LED would have such intensity. Maybe because the PAR readings were taken in a 4x4 and I’m growing in a 3x3? But I had the lights as high as 40” above the canopy… I don’t understand so I’m leaning on the expertise here. Oh I don’t know if it matters but I also hit the plants with a day and a half of 24/7 light to try to encourage them to start growing again. They got 24 hours of light for a day and a half then I noticed they didn’t like it at all (even though the light was 42” above canopy). It’s been a week since then.

The images are the progressive decline of the plants. There used to be 3 in the tent but I moved that one outside almost 2 weeks ago as it wasn’t recovering from being stunted after mainlining. It’s doing very well outdoors now.



Here are the PAR meter values as per manufacturer:

 

Temperature in the tent is steadily at 27°C except at night when it drops to as low as 17°C - I know this could be stunting my plants’ growth but I haven’t sourced a smart heater yet. I water when the plant needs. I usually test by weight then do a 2” finger soil check. Watering with Grow Girls Grow by Deutch Science every water maybe 2x a week. Plants take about 600 ml of water each before runoff.

 

Now that you mention water… I haven’t been pHing my water because I was using bottled water but I’ve recently switched to tap water… checked with a pen and it’s at 7.8 with 199 ppm. The ppm is within range but he pH is off. I’d have to check with feed to see if maybe the feed drops the pH to a better range but it could be the water… are we SURE it’s not the lights?

 

Confirmed it’s the light. They’ve been outside since posting. Now look at them.

 

Yeah I think I’ll have to purchase a Par Meter and measure it myself. I think a big factor is my tent is 3x3 not 4x4 like their tests so my light must be much stronger. Maybe I can get away with just using the Veg setting until they’re ready to flower.