Whats The Deal Wit These Plants???

[jon.hatcher]

My vote is on heat stress.

[OLDJIMMYBONES]

well it could be heat, i am at the molment vetilationless, and the mh buld makes a lot of heat but the temp never hits over 102F

[OLDJIMMYBONES]

but not sure if it is def the heat since all my other plants are fine + it happen to all these seeds even before i transplanting from cfl to the mh

[Weedhound]

well it could be heat, i am at the molment vetilationless, and the mh buld makes a lot of heat but the temp never hits over 102F

NEVER over 102.....thank god for that...:wtf:

[OLDJIMMYBONES]

why what it the ideal temp?

[Opie Yutts]

Like 78 or something. That's just my goal for my set up. It usually is more like 84 or so, but I could always pull the light back some. The warmer it is the faster they grow, within reason, but then heat adds chances for stress, mold, fungus, and root rot.

[Dutch Pimp]

NEVER over 102.....thank god for that...:wtf:

.....:S2:

[Weedhound]

Just teasing you Jimmy.....you said that so innocently. Ideal room temp is about 70....keep under 80 if at all possible.....opie's stretching at 85 imo BUT the REAL key is this.....(shhhhh) when the leaf surface temps go over 80 degrees (usually at about 85 degrees room temp or so depending on ventilation, how close your light is etc..) the plants growth will slow down tremendously. Photosynthesis drops a HUGE amount (in fact almost to 0 if I remember correctly) when leaf surface temp exceeds 80 so while your plants may seem fine-ish at a higher temp.....it behooves both you and your plants to keep temps down.

You can buy yourself a cheap $20 handheld temp gun and that will give you an accurate reading of your leaf surface temps.

[Opie Yutts]

Weedhound, would you say that when the air is 80, so is the surface of the leaf? Or is it cooler than air temps because there is moisture circulating through it and evaporating from it? Or is it hotter because HID light is bouncing off it?

[Opie Yutts]

Oh here we go:

...evaporating water cools the leaves below that of air temp...

http://www.plantstress.com/articles/...SI_phoenix.pdf

It's a little technical, but it's interesting and answers some questions.