Curling Leaf Margins...??

[billyba79]

Hey guys, thanks for taking the time to read my post. I am working w/ G13 Haze around 8 wks into bloom (they have about 4 wks left). I am using black gold soil w/ perlite and rainbow grow mix added in for nutes. Also got some dolomite lime in there too. They are under a 400w HPS w/ a sealed reflector that has tempered glass and a 6 in can fan filtering out the room thru the light to keep cooler. My room runs around 85 degrees F (I know it should be lower, but that's as low as I can get it with this set up). I water every 4 days and give 'em nutes about 1 time/wk. Everything is organic. I use worm castings, molasses, liquid seaweed as a base tea and when giving nutes I use guano (High P now in late bloom) and once every few weeks give them Earth Juice microblast and Earth juice meta-K. I also had a bad run of fungus gnats so I had to add Gnatrol to my water for the past 6 wks (stuff is a little expensive, but works great).

Now after the intro...the problem starting showing up about a week or two ago. The main issues are the leaf margin curling up towards the middle of the leaf and these random necrotic spots. This is affecting about 1/2 my plants and the necrotic spots are on the middle fan leaves. At first I was thinking heat burn, so I moved the light up probably close to 14 inches above top of canopy. Really didn't do any good. Then after reading on different forums and referencing Jorge Cervantes book, I started thinking Mg def. I added 1 tsp Epsom Salt 2 days ago and watered pretty good. I can't say I made an improvement. Actually worse now...SHIT! I'm out of ideas.

I don't know the pH of my soil, but I've read that when you are using pure organics that pH isn't a issue with the microherd kicking it down under in the root mass. I will check with next watering. All help welcomed and appreciated. Thanks again. Peace and keep it green.

 

[Weedninja]

I'm not 100% sure on the necrosis, but the curling is heat stress.

 

[accessndx]

You need some lower temps....and some cal mag my friend.

 

[billyba79]

Maybe I guess, but I thought that mj could take temps up to mid 80s w/o too many problems. Man, in the past I've grown in much warmer conditions w/o problems. No problems for the 1st 8 wks either, why would heat stress show up now and not earlier? I'm just thinkin' out loud, not trying to hate on the advice. It's much appreciated.

 

[wygram]

Some plants can take the heat, others can't as you're seeing. BTW that is extreme heat stress. A HPS throws radiant heat hard and you might not be capturing the temperature at the level of the tops... where is your temperature probe placed? Is 85 the room temp? The deficency is more likely than not caused by the extreme heat stress locking out whatever it is that is deficient. Fix the heat (search for CMH, experience tells me is runs cooler than HPS) and then move on to other problems.

 

[billyba79]

Well, if it's heat stress, there isn't much more that I can do. As I said earlier, the light is 400w and is in a sealed reflector w/ a 170 cfm can fan blowing air thru the light to keep it cooler. I can hold my hand 2 inches under the light for minutes w/o my hand getting overly hot. What else can be done here?

 

[wygram]

If you can hold your hand 2 inches away from the glass without "discomfort" you must have asbestos hands. If the back of your hand really doesn't feel anything more than warm, hot is too much, I guess your plants should be ok since you have it 14 inches away. Let me ask: how are you venting the room or is the heat building up?

 

[AndreNicky]

I had the same thing happen to my hindu skunks with the leaf curling, didn't happen to any other plants and the temp of my growroom avgs. 80F. I didn't pay too much attention too it, didn't really seem to effect the overall quality/yield of my plants

 

[billyba79]

For venting the room, I am using a 6 inch Can fan pulling air thru a filter and the output is going thru sealed reflector. From the reflector, it is going directly out of the room by ducting. That's why I'm a little hesitant to think that it is heat stress. I mean it could be, but the room isn't really that warm and the fan keeps the light fairly cool. My hut has intake openings on the lower sides of it. (got it from Worm's Way).

Andre, I hope ur right. I'm really starting to sweat this problem. Grow and the 1st 8 wks of bloom were peachy, only problems that I ran into was fungus gnats. Go figure, can't seem to get a grow w/o running into some sort of problem. Just takes time I guess.

 

[AndreNicky]

The way u vent your room sounds confusing to me, why don't u just have it exhaust directly from the light instead of the hot air being pushed thru it? I vent my whole room thru my air cooled hood and it works wonders

 

[wygram]

I agree with nicky. Switch the position of the fan in the set-up if you can and see if it makes a difference. Filter, hood, fan and then exhaust.

 

[billyba79]

Not really understanding what your saying. I have a filter w/ a fan on it. It pulls fresh air in from outside of the hut and thru the filter (passive intake). It's pushing the filtered air thru the hood and out of the hut. It functions to bring fresh air into the room and also to cool the room as well by venting the heat from the light outside of hut. I'm not pushing hot air thru the filter, I am pulling cool air and pushing it thru the hood and then directly outside the hut via ducting.

 

[Old Soul]

Detach the fan from the filter. Have the fan on the other side of the light pulling air through it and then pushing it out of the box.

 

[billyba79]

Hey Old Soul, what is the difference b/t having the fan on the other side of the light. Will it cool better? It seems that the only difference b/t that and the way that it is set up is one way will have air pulled thru the light and the other will have air pushed thru the light. Is there something that I am missing? Also, I don't know if I can do that. The fan is too heavy to attach to my hood (I do think the ceiling supports of the hut will handle more weight than it has already with the cool junior hood). Thanks for the input and please keep the ideas flowing.

 

[billyba79]

Gotta head out and run some errands, will be back in a couple of hrs. So, if I don't get to respond right away, I will for sure get back with all the great input in a bit. Thanks again and keep growing.

 

[billyba79]

Hey guys, would high humidity cause the leaves to curl up like that? Man, I just checked while the fan was off and the humidity was 75%. I was only running the fan with the lights on. Maybe this could fix'er up.

 

[wygram]

No, humidity would definitely not do that to plants. You might want to run the fan in later flower to lower humidity to prevent mold. This is definitely a heat issue. Try looking at CMH bulbs, they run cooler than a HPS. BTW What is the filter for? Doesn't sound like it's a carbon scrubber since you are pulling in air from outside through it... It also seems like your setup doesn't exchange the air in the room with what I've understood as a closed vent system for the light.

 

[billyba79]

It's set up like a carbon scrubber. The filter is open to pull the air inside the hut out thereby passively bringing clean air thru the air openings on the lower ends of the hut. I do not have duct bringing air to my filter. That air leaves the filter then the fan thru 2 ft of ducting to hood, ducting out of hood leaving to outside hut. Make a little more sense?

 

[wygram]

Yup now I got it. Well the best would be to mount the fan after the hood, which would increase the flow of air across the bulb. Pulling in this case is better than pushing. If you really can't do that then try to straighten, as much as you can, any bends in the ducting as well as try to reduce it's length. Other than that there isn't much you can do.

 

[billyba79]

I gotcha. Yeah, I tried to keep the length of duct work to a minimum and there are as few bend in it as I could get. Thanks for the reply and keep it growin'.