Wind burn, ambient temperature, deficiency, relative humidity ?

Hey guys

I have done a bit of digging in the sticky threads but can't find an answer I can be sure of, hence coming here.

Ambient temperature is about 21 degrees, and radiant temperature is 31.

Plants are on 1.0 EC canna nutrients feed on a wilma system every three hours.

I increased the feeds to three hours on account of the low (10% - 15%) humidity.

They're under an air cooled 400w metal halide at about 9" height from the pots.



This leave curl is happening across my entire system (there are two tanks), under two different lights, I don't think it's a nute problems as they're dialled in as per tried and tested quants, strain is critical mass 2.0.



If anyone can give me some advice that'd be great !

Cheers

K

Apologies for the photo spamming, literally just woken up

If it were me, id back that 400 up like 6-8" & attempt to humidity the area without wetting the leaves.

Do you think the cause is the light being too close, or the low humidity, or a combination of both ?

Kieron90 said:

Do you think the cause is the light being too close, or the low humidity, or a combination of both ?

Click to expand...

Just low humidity. Looks like they can handle the light just not the heat/low humidity.

See the edges crinkling up? If you were at 65% RH they’d be fine. 26 is too low at this stage.

If I were you I’d back the light off. 400wmh have a good depth. Get the temps down a tad but get the humidity up to 50-60% range.

A humidifier is on the list for today in that case, it was on the to do list but I'll make it a priority. I've measured the humidity of the air on the in take and it's 50% - that's dropping down to 10% because of the lights and the air circulation right ?

I've moved them onto continuous feed to hydrate them and backed off the lights until I pick up a humidifier this afternoon, just as well the room was getting sorted today.

Cheers

K

Kieron90 said:

I increased the feeds to three hours on account of the low (10% - 15%) humidity.

Click to expand...

never heard of this

Never heard of what, the low humidity, or the corrective action...

I just bought some more meters to make sure the measurements I am getting are correct.

I grow in 20% RH (all my life) and never saw that stress on my babies. The lights too close. Should be using T-5s until 3-4 weeks or raise that light about 2-3 feet. Don't feed those little fucker hardly anything yet.

Moldy said:

I grow in 20% RH (all my life) and never saw that stress on my babies. The lights too close. Should be using T-5s until 3-4 weeks or raise that light about 2-3 feet. Don't feed those little fucker hardly anything yet.

Click to expand...

Ditto. Lights to close

Moldy said:

I grow in 20% RH (all my life) and never saw that stress on my babies. The lights too close. Should be using T-5s until 3-4 weeks or raise that light about 2-3 feet. Don't feed those little fucker hardly anything yet.

Click to expand...

Like this..... IMO ... Cxm22's 1.4 amps less than 400watts. They are like 27" from the girls, they love it.

Moldy said:

I grow in 20% RH (all my life) and never saw that stress on my babies. The lights too close. Should be using T-5s until 3-4 weeks or raise that light about 2-3 feet. Don't feed those little fucker hardly anything yet.

Click to expand...

I’m having a night mare below 30 %humidity your doing well. Different strains or just one strain?

All strains and grow rooms are different. But heres the facts. Raise that lamp up a foot...and increase relative humidity to 55 - 70%. Its just little seedlings. They love more moisture in the air. Back the circulation fan off a skosh and lower the EC a tad. They will come around. I can tell yer from Europe.

Reduce your EC to 0.6. You'll be getting nute burn at 1.0 with your low RH. I have the same issue here and rather than try to keep the RH up I'm going with lower ppm. Worked great on my last grow with no burn or toxic salts buildup turning my leaves all dry and crispy.

The plants are pulling more water and thus more nutes so even at the lower ppm they will get lots of nutes to grow just fine.

OldMedUser said:

Reduce your EC to 0.6. You'll be getting nute burn at 1.0 with your low RH. I have the same issue here and rather than try to keep the RH up I'm going with lower ppm. Worked great on my last grow with no burn or toxic salts buildup turning my leaves all dry and crispy.

The plants are pulling more water and thus more nutes so even at the lower ppm they will get lots of nutes to grow just fine.

Click to expand...

Makes sense to me thanks for input you just helped me so much! I reduced nutes soon as I realised they wasn’t happy I put it down to over nutrients as I just switched up to all mix instead of light mix, now I learnt that I got yellowing because I still need a little nutes as well, whenever I see unhappy plant first thing I do is cut nutes and feed water in case of nute burn probably an amateur move but I cut out one potential problem by doing it this way after a couple waters I add low dose nutes and normally see a recovery but not this time so I learnt it’s something else

since1991 said:

All strains and grow rooms are different. But heres the facts. Raise that lamp up a foot...and increase relative humidity to 55 - 70%. Its just little seedlings. They love more moisture in the air. Back the circulation fan off a skosh and lower the EC a tad. They will come around. I can tell yer from Europe.

Click to expand...

seriously raise my lights will increase humidity

Jimmy the vest uk said:

Makes sense to me thanks for input you just helped me so much! I reduced nutes soon as I realised they wasn’t happy I put it down to over nutrients as I just switched up to all mix instead of light mix, now I learnt that I got yellowing because I still need a little nutes as well, whenever I see unhappy plant first thing I do is cut nutes and feed water in case of nute burn probably an amateur move but I cut out one potential problem by doing it this way after a couple waters I add low dose nutes and normally see a recovery but not this time so I learnt it’s something else

seriously raise my lights will increase humidity

Click to expand...

I have just been experimenting with light distances trying to stay as far away as possible

Leave the fans, you really need to blow directly at a plant the whole time to harm them (they will be smaller).

PS: 18" would be where I put my 400s with seedlings that small. As close as 8" when they're a lot bigger. Even closer if I have them on my Light Rail 4.0.

ANC said:

Leave the fans, you really need to blow directly at a plant the whole time to harm them (they will be smaller).

Click to expand...

Cmon bro. Really? With little seedlings like hes got? I know where yer going..but cmon.

I use a fan on my seedling bags even before the seed comes out.