directly under the lights temps get close to 90 even 95(even with a fan blowing directly on the canopy) when the co2 is running.... if i move the thermometer away from the lights it drops to 80-85...... i dont see any slow growth issues.... where do you guys measure your temps from?
where do you measure temps?
- Thread starter mobby420
- Start date
bigv1976
Well-Known Member
Measuring temps under your light is not giving you and accurate reading. There are actual temps and radiant temps. That is why it is 95 because your light radiates alot of heat. I would measure away from the light. MJ can tolerate higher radiant temps than overall temps.
Thanks bigv, that is what I thought. just wanted some other insight as the radiant temps do get 10-15 degrees hotter at times!
Brick Top
New Member
I use an indoor/outdoor thermometer and have the outdoor sensor at canopy height and the indoor sensor part, the part you would read the temperatures from, at pot level. That gives me what would pretty much be the low and the high temperature so I know if the root area is too cool or if the canopy area too warm.
what are ideal root temps ? how much cooler than above the canopy? i was always told to keep pots/whatever your growing in off the floor to prevent from getting too cold
treemansbuds
Well-Known Member
Hello All-
Not sure if there is a perfect root temp, but I do know that is why growers grow in raised beds, to increase root/bed temps. More surface area exposed to the sun = warmer root/bed temps.
TMB
Brick Top
New Member
One thing I read about low soil/root temperatures, in crops, was low soil temperature inhibits the effect of high nutrient supply on photosynthetic responses resulting in slower growth. I have never read an optimal root/soil temperature for cannabis plants but when the temperature around my root zone remains roughly between 70 and 75 degrees I see better growth. When it has dropped to around 62 to 67 I have seen a noticable slowing down of growth. Something else I read about low soil/root temperatures in crops is low soil/root temperatures cause a differentiation of root tissues, possibly through effects on carbohydrate supply to root meristems slowing down cell division and creation.
Where I first saw it while growing, and then what caused me to later read how root temperature in crops makes a difference, is I switched pot sizes once, the one time I dropped down to a 4-gallon sized pot, and the large thick clay-looking plastic drip trays I used with my 7-gallon pots just didn’t work well, the fit was way off. Being in a hurry I purchased some cheap thin plastic drip trays that were a perfect fit. I started out some seedlings and growth was almost non-existent. Everything else I was doing was exactly what I had done in the past so at first I thought it was the plants.
Later, much later, after much scratching of my head, I placed a thermometer in one of the then empty plastic drop trays on the floor, which was my basement floor and took a reading and then did the same thing using one of the thick plastic clay-looking drip trays. I do not recall the temperatures but there was roughly a four-degree difference. Evidently the thick plastic clay-looking drip trays insulated the bottoms of the pots from the cold basement floor enough to keep the soil in them slightly warmer and the difference was enough to cause slow growth. I have grown the same strains again from the same group of seeds using my larger pots and larger thicker drip trays and I have not seen the same slow growth, nor have I see it with anything else since. It was the only time I have had growth so slow that after days I could go back and look at the plants and they looked like I was looking at a photograph of them from days or more back. They looked healthy, the color was good, what leaves were there did not show signs of any problem … but they just remained tiny for what seemed like forever.
Where I first saw it while growing, and then what caused me to later read how root temperature in crops makes a difference, is I switched pot sizes once, the one time I dropped down to a 4-gallon sized pot, and the large thick clay-looking plastic drip trays I used with my 7-gallon pots just didn’t work well, the fit was way off. Being in a hurry I purchased some cheap thin plastic drip trays that were a perfect fit. I started out some seedlings and growth was almost non-existent. Everything else I was doing was exactly what I had done in the past so at first I thought it was the plants.
Later, much later, after much scratching of my head, I placed a thermometer in one of the then empty plastic drop trays on the floor, which was my basement floor and took a reading and then did the same thing using one of the thick plastic clay-looking drip trays. I do not recall the temperatures but there was roughly a four-degree difference. Evidently the thick plastic clay-looking drip trays insulated the bottoms of the pots from the cold basement floor enough to keep the soil in them slightly warmer and the difference was enough to cause slow growth. I have grown the same strains again from the same group of seeds using my larger pots and larger thicker drip trays and I have not seen the same slow growth, nor have I see it with anything else since. It was the only time I have had growth so slow that after days I could go back and look at the plants and they looked like I was looking at a photograph of them from days or more back. They looked healthy, the color was good, what leaves were there did not show signs of any problem … but they just remained tiny for what seemed like forever.
Brick Top
New Member
At our nursery our starter beds they are not raised, they are lower than the surface of the ground to protect the plants from wind desiccation but we have pipes running under the beds where warm water is pumped through in the spring. At the time I should have thought of that and put two and two together with my slow growth, but I didn't.