SOIL Is this heat stress?

[mlynch475]

Is this heat stress?
temp: 75-85°f
RH: 55-60% but my humidifiers have been running out so I've seen it as low as 39%. I ordered larger.
Co2: 1500ppm
Light: 620-650ppf for 18hrs. Full spectrum led
strain: strawberrycough and chicolope
Medium: promix bx
Nutes: fox farm lineup at 1.6ec

[Canuck147]

Are your humidifiers blowing on the plants?

[SoOrbudgal]

Looks to be heat and nute issue.

[PLreef]

Sure looks like the beginning of heat issues. Raise your lights a few inches, increase fans

[mlynch475]

I think budgal got it on the nose. Heat stress and small nute uptake problem due to high soil ph.
Watered with nute solution ec 1.6 ph 5.2. See if that brings it down.

My humidifiers blow into my canopy fans.

I use cloudline exhaust fans so they increase speed when triggered until temp falls below target then cycle down.

My lights are already over 3' away. I use a roi-e680 from growers choice and a sf7000 from spider farmer.

Thank you guys so much for the help! Fast community response

[dilvish]

if your lights are 3 feet away then it's not light burn. Besides the tips would go white or yellow. It may be a tad warm in there. You didn't mention how often you water. Let them dry out a bit to the first inch or two deep. If using coir, PH should be 5.5 -6.5 remember to test PH after adding nutes to the water.

If I had to guess I'd say it was a spillage. sometimes when you feed with nutrient mix, you get some of the leaves and it burns them.

They are in Veg so let them go a bit. keep the nutes at recommended levels especially nitrogen because they need more during Veg.

Also, which is it 75F or 85F? a 10 degree range is a big difference! FYI some strains like it cooler (White Widow), some like it arid (Alaskan Purple), some like more light (Northern Lights), so you need to know the strain specifics...is this both plants or just one...which strain is it strawberry or chicolope?

[PLreef]

I have the same light. It's 8" away from the colas at 100%. So with ruling out light burn it could be heat stress. But those rusty spots look like one of 3 possible issues.
1* heat stress
2* PH fluctuations
3* the start of a calcium deficiency

[mlynch475]

Thank you so much for your responses guys.

I'm going to create a grow journal on here entitled My first grow: The sativa experience (most likely tomorrow as it is quite late here). I will ofcourse answer all of the above questions there. I originally created a journal on another popular forum but after 2 weeks of no responses I came here. And wow the difference!

Thank you again growweedeasy, for the forums and all the articles.

[MrPNW]

I’ve got the SF4000 in a 5x5 and my strain hated bright light until late into flower. I couldn’t takes it above 60% @30” above canopy. Once they matured I slowly raise the dim.