Impact of heat stress during veg?

[Caligreen]

Hi,

I have some young ones, about 3 weeks old, under a 400watt mh lamp, they are about two feet below it, with a six inch personal fan blowing over the canopy. They are showing signs of heat stress as some plants have only developing 3 or 4 blades per leaf. Other than that though the plants seem very healthy with bushy, vigorous growth.

Is this going to create signifigant problems?

The flowering room has much better temerature control and will stay in the appropriate range (below 80)

[harris7]

your heat stress is probaly caused by radient heat. not the heat of the room. my room is up to 95 F with no signs of heat stress. but back when the lamps got too close a few times we had some heat stress.

so just back off the lamps.

what are the effects of heat stress, you getting deformed leafs? at the top

[dutch.lover]

i would like to know if heat stress causes significant problems as well. anyone?

[Cyclonite]

Mine were severely overheated once but and im sure it hurt the yield but they still did good.

[Caligreen]

definately radiant heat, the room temps seemed fine, I moved the lamp up another foot...

anyway, i have some 3 blade leaves, so i guess the plant wont be sucking up as much energy from the light as it would with 5, so maybe the growth could be a little stunted. Anyway, I dont think there is a signifigant problem with high heat levels in veg...

during flower though I hear it makes for very light, fluffy buds, and that is a signifigant problem

[kindprincess]

to answer the original question...

in the long run, your plants will be fine; just give them a week or so, and they'll be back into full swing.

also, if your lights are at 2 feet, there's almost no way your getting radiant burns... i'm using one in the basement, 8 inches from small plants radiant temp of 90 degrees, with almost no ventilation. i have no burns...

so, i'd say your problem is ambient heat; a solution would be to make a cool tube for you mh, to suck out the hot air from the bulb, or, get a bigger exhaust fan, cut a hole to create a passive intake. this will lower your temps to whatever your intake temp is, depending on the size of your fan...

in my flowerbox, i use a box fan as an exhuast, flowing straight into my room. i cut holes in the bottom of the box to allow a return... sooo... now that it is cold out side, and we have a buck stove for heat, the house is usually 55-60 degrees. in my room, the cool air is replaced by the hot air of the box. the result is a nice and even 72 degrees, box and room:) so the light is my heater, which uses 1100w less than a space heater:D

stoner genious;)

love, kp:p

[justaseed]

some strains only have 3-4 blade leaves in veg naturally. my favorite strain to grow, master kush, never has more than 4 blade leaves in veg(sometimes only 1-2 or 3 blades) but 5-7 blade leaves start to show the 1st 2weeks of 12/12. just genetics i guess as the veg temps are 75-78 using 8 4ft agrosun flouros with a 465cfm squirrell cage for ventillation. it is the only strain i've had that does this.

[stinkyattic]

my favorite strain to grow, master kush, never has more than 4 blade leaves in veg(sometimes only 1-2 or 3 blades) but 5-7 blade leaves start to show the 1st 2weeks of 12/12.
.
That's interesting.
A couple of the plants from my "BOG Mix" only have leaves with 3 blades and 2 tiny stubs... even in flower!
Heat stress can stunt your plants and make them transpire so fast that you have to really keep up with the watering.
Get the temps below 80 -stick your thermometer right at the canopy- and give a silica supplement. I have temp problems in the summer in my veg room sometimes- up into the 90s even- but using the Silica Blast they seem much happier.