Grow Mediums seedling heat mats under autopots

[lunarman]

Living like in a northern climate. Winters are long and harsh. Indoor growing but in garage that is colder than a house thats for sure. its insulated but not heated. I have to run quite a bit of heat in the tent (oil heater) to get 25C ambient temp during the winter. I do have a slab of chip board between the concrete floor foundation and the tent floor too. Also 8 inches of insulation batting on the top of the tent.

And of course I'm looking to get that little bit more towards better grows. And reduce electrical bills too for that matter.

I have totally ignored soil temperature but now I'm thinking this is something to look at. I started with one seedling mat under two pots with new tap rooted seeds and although I have no hard data I feel its making a difference after a week. So I bought 3 more mats for a total of 4. I run 8 autopots. Right now its too early for the irrigation trays and valves, but once I add them in at day 20ish, the worry is the heat might to too much for the nutrient feed in the trays (Mega crop).

I know about the thermostat controller for heat mats. But not sure how to proceed now. Maybe buy a thermostat for one mat to compare against not having control and see how the plants react. Also thinking it would be smart to measure the temperature of the water in the trays. But what would the ideal temp be for water in the tray? Or should I measure the temp of the roots at the bottom of the tray?

 

[lunarman]

Is everyone on holidays around here? Nobody has any advice to share on root zone temps? Or what device works well to measure temps and what is a good temp range? I thought that was important shit to know for a grow. I do need some advice if you have any.

 

[Mizzo81]

I would say upper 60’s to lower 70’s for solution. I hand water and that’s where I have my temps

 

[lunarman]

I would say upper 60’s to lower 70’s for solution. I hand water and that’s where I have my temps

Thanks Mizzo. I searched growweedeasy.com but didn't find anything on root zone temps. Did not try google yet. I'll have to go measure the bottom of my pots to see what the temp is without the trays/valves. And I'll measure the liquid temp when I turn the system on later.

 

[Mizzo81]

No problem brother

 

[Mizzo81]

On that note that would be for plants past the seedling stage. During the first two weeks I would say warmer, mid 70’s at least maybe even warmer.

 

[BII]

You haven't mentioned the most important thing -- What is the actual media/soil temperature, the extent of our problem?

But why go the dangerous path of heated mats vs. say just good insulation and/or air space under the pots?

Simplest is to just raise the "slab of chip board" flooring or the pots a few inches off the floor, enough to to allow tent air flow to keep everything at consistent air temperature. Nearly everybody growing indoors and outdoors is doing this, just relying on ambient air to keep their plant roots at suitable temperature.

 

[lunarman]

On that note that would be for plants past the seedling stage. During the first two weeks I would say warmer, mid 70’s at least maybe even warmer.

I used an infrared thermometer pointed at the outside of the black autopots and an inch from the bottom and I got mid to high 70's. So that must be pretty ideal for the little girls. I have 4 mats now under 8 pots for 24 hours and I can't say I see a difference. But longer term I hope to see a difference in growth and in hopefully also a reduced electrical bill. I think I'll have to reduce the temp's later in flower maybe with thermostat controllers. Or I might put a buffer material between the mat and the bottom of the pot to reduce the temp in the pot and tray.

 

[lunarman]

You haven't mentioned the most important thing -- What is the actual media/soil temperature, the extent of our problem?

But why go the dangerous path of heated mats vs. say just good insulation and/or air space under the pots?

Simplest is to just raise the "slab of chip board" flooring or the pots a few inches off the floor, enough to to allow tent air flow to keep everything at consistent air temperature. Nearly everybody growing indoors and outdoors is doing this, just relying on ambient air to keep their plant roots at suitable temperature.

I was looking at rigid foam insulation to cover the 8x8 tent floor. And I will continue to look at it and will buy eventually. Probably be a good idea to do the full floor space, not just under each pot. I just picked up insulation batting an have 8 inches of it on the tent roof.

 

[bushmasterar15]

In some searches I just did I'm finding healthy root zone temperature is generally accepted to be in the range of 67–75 F for cannabis. I have 1/2" foam padding under my tent to give a buffer space from the concrete floor to the autopots in the tent.