Probably a stuopid question about growtent temperature measurement...

[Firstsecond]

Alright, this might sound straight dumb, even to me, but lets get it over with.

Normally, whenever you discuss outside temperatures it is measured in the shade...
Several guides, books, tutorials etc give you the optimal temperature range for cannabis growing...

So in a grow tent, how do you properly measure the temperature?
I get quite significantly different readouts, weather i place the sensor on the floor where little wind hits it, on the soil level etc. and obviously they all differ if the sensor is directly hit by light or put in shade... I know the rule of 'comfortable hand', I was just wondering what you ppl use as reference measuring point and how.

Cheers.

[Royal Nugs]

I struggled with this one for quite a bit when I first started growing.

I now have a little infrared thermometer I picked up for $20. I use it to measure leaf temperature. I find it to be the most accurate. I noticed my thermo/hygrometer reads a few degrees higher in the light than the leaf temp. I still keep the other meters in the tent for humidity obviously but also as a reference for temp. If I get higher or lower than my norms, I'll bust out the infrared.

[Mañ'O'Green]

Normally you want the temperature at the canopy. I have a sensor that broadcasts to a remote console both temp and humidity and a problem occurs if that sensor is too close to the canopy. It reads humidity too high because it is sitting right over the transpiring leaves and if it is too far above the canopy the temperature is off! I prefer to monitor humidity more accurately over heat so I am about 3" above the canopy. Move yours around; after a while you will get a sense of what works in your setup.

[Weed Pharma]

Since my grow tent is inside a temperature controlled room, I don't worry about the temps when they are in Veg and use the unit for the days range-
The unit is generally placed at soil level or below.

When they are in flower, that's a different story;
I place the unit at the same level as the canopy and use a non-contact infrared gun-if the temps are off.
The plants temperature will usually be lower - unless there is an issue with the plant's health, water, soil temp etc.
This type of measurement is used in agriculture as a Plant stress monitor. (I have the study somewhere, but haven't been able to correlate the data with inside grows).

Found the link: http://www.agriculturesolutions.com/...tress-monitors

[Wattze]

This is incredibly awesome knowledge! I'm definitely going to be keeping this in mind!

[Wattze]

Just commenting one more time. I went and read that article, and that I.r. Gun is awesome! Incredibly powerful tool to use in my future grows! I feel like that would be a worth while investment lol

[Smokey McPot]

You would ideally use two thermometers, a wet bulb, and a dry bulb, side by side. Both thermometers should be shielded from radiation and the dry bulb thermometer should be just that -- dry. The web bulb thermometer has a piece of muslin (etc.) soaked in water and wrapped around the bulb. The dry thermometer is 'air temperature', while the wet thermometer gives the adiabatic saturation temperature; i.e. the minimum possible temperature a leaf surface could be, cooled through transpiration. This depends upon relative humidity (dew point, temperature). It will read lower.
The canopy should not be dense enough that condensation forms of leaves. During flowing this can cause budrot (mildew) to thrive.

The upper canopy temperatures are the important ones. The dry air temperature of the 250mm, or so, above the top of the canopy indicates whether you have enough airflow under your lights. Forced cooling lamp fixtures will do a lot to reduce these values, but won't help with rustling the leaves, keeping away condensation.

[kingfish]

You guys are way to sophisticated for me. I have a thermometer sitting on a milk crate in the middle of the tent. As long as it won't go over 80F I'm happy. If it does, I make adjustments. I'm not smart enough to use all that fancy stuff.

[NebulaHaze]

I have to admit I also keep it simple. When the plants are young I just leave my temperature/humidity monitor next to the seedlings so it's getting exactly what the seedlings are getting. Once the plants start getting bigger I just stick it on the side of the grow light reflector/hood (the thermometer is magnetic), trying to place it somewhere that's not getting too hot from the bulb. It's not perfect but it gives me a general idea of whether the temperature in the space is going up or down