Leaves Going Brown And Curling

[emperorzallin]

Look at the state of this, I am growing 4-way in biobizz allmix, this plant has been on 12/12 a about a month. The tempertaure in my cupboard goes from 20-30 on my min max. The top of the plant is about a foot and a half away from my 400 wat sodium light.

I'm using biobizz grow and bloom, though for the last week or so it has had none cos me and my mate thought it may have been too much nutrients. I was giving about half a capful of each per litre.

I have also given it some epsom salts, though looking through the FAQ I don't think this looks like Magnesium deficieny.

[emperorzallin]

here's the whole thing.

[Bish]

I'd say a lack of Co2 mate.

Check this thread out.

[emperorzallin]

I had problems with the temperature and ventilation to start off with (not on these plants) it was getting as high as 40 deg C, so I got myself a decent fan, 150 mm xpelair XID inline duct one (I'm growing in a cupboard about 2x1x1.5m), this has kept the temp down to 30 tops and it's been a lot hotter lately, I'm pretty sure that's enough ventilation to get the amount of CO2 I need.

I sat in there for ten minutes once to test how light tight it was and it felt nice and fresh. Not that that proves anything very much I suppose.

My friend has a 4-way plant with less of the same problem and much much less ventilation.

Edited May 25, 2004 by emperorzallin

[emperorzallin]

hotter weather outside lately I mean

[Bish]

150 mm xpelair XID inline duct one (I'm growing in a cupboard about 2x1x1.5m), this has kept the temp down to 30 tops and it's been a lot hotter lately, I'm pretty sure that's enough ventilation to get the amount of CO2 I need.

Where are you drawing air in from though mate? Is it fresh air from the outside?

[oldtimer1]

If the grow area ambient temperature is rising more than 2 deg C above the the input air ambient the air exchange is totally inadequate. That does not mean the fan is at fault it could be the input.

ie if the input duct air temp is 28C you would expect the extract duct air to reach 30C or a little less.

You have to look at the total circuit from the outside back to the outside. For instance the absolute minimum free space for air input from the outside should be 145 sq inches

As you say your grow room temps are reaching 30C something is very very wrong with your ventilation as peak outdoor temps have not gone over 21C yet this year, so at the hottest part of the day the grow room temp should not rise above 23C.

Cannabis stops growing round 29/30C at background Co2 levels of 300 to 320ppm. But as long as those levels are maintained no damage will happen to the plant until temps are approaching 40C they just don’t grow is all.

[noddybud]

I got symptons like that on much younger plants due to root rot after overwatering for a period of time. I can't say 100% that it is the cause of your problem though. Just my two penneth.