Germination mat with temperature controller

I’d like to purchase a greenhouse heat mat, and while searching find some come with a temperature controller (more $) and some come w/o a heat controller. I happen to have a spare Inkbird 308 Temperature controller that can control power on/off to any device via a temp probe that senses a value that I can set.

Would the 308 Inkbird I already have function similar to the way a mat that comes with a temp sensor also function? This would save me $30 if I just bought the heat mat and could set the Inkbird to turn off at 78F (for example). I guess I’d simply lay the probe on the mat and tape the probe down flush on the mat to ensure full contact? Any ideas…is this a plausible idea?

I cant see a reason it wont work, and if it saves u 30 bucks i say all the better. I am a big fan of diy stuff and saving a buck or 2. I think its a great idea. U basically have the components they charge xtra for, just my thoughts.


Looking at the devices coming as a complete kit, I honestly cant see why my DIY idea wont work as well…or maybe better since the Inkbird is good stuff.

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I would rather use light to heat my area… the best of both worlds and cheaper… throw some lights on them… that will increase temps … :wink:
And you will increase photo synthesis at the same time… no need to fight the other… :wink:



Yes, it’s exactly the same thing, just not as good as the inkbird.

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Just throwing this out there… last week I bought a heating pad, some Rapid Rooters, a tray and a humidity dome. I asked the vendor about a temperature controller, and he said he really didn’t think they were worth it for the results versus cost. He recommended saving some money and just using an outlet controller set to whatever I needed to maintain the temperature I wanted - e.g. 15 minutes on, 15 minutes off or 45 minutes on, 15 minutes off, etc.


That looks almost exactly like what I use for my clones and seedlings. I have two T5 2ft 24 watt high output lights over my Dome. underneath the Dome I have a heating mat w/o a temp setting function. I have fairly good success so I don’t see why you wouldn’t. For the record I grow in a basement. So it’s a little cool especially this time of year. Good luck and enjoy your grow!

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I surely see his (and your) point. Luckily I have the Inkbird temp controller sitting here available, so may as well use that since I don’t need to go out and buy one…which would shed an entirely different light on the subject.

May I ask (if you remember), to look up this thread once you have tried your heat mat and dome and give a short review of how it performs for you? I know they can get 10F - 20F over ambient temps, so I suppose it boils down to what ambient conditions you have available to operate the system.

Okay - I haven’t actually used it yet, but I’ve been doing some testing. I have a timer hooked up to the heat mat. I have both of the vents on top of the humidity dome wide open. Here is what I have found so far:
Room: 67 degrees, 44% humidity
Heat mat on 24/7: 88 degrees, 44% humidity
30 minutes on, 30 minutes off: 77 degrees, 44% humidity

When it gets to be summer I’ll probably have the heat mat on less, but for right now 30 on/30 off seems pretty good.
One thing I’m not sure of is… are we supposed to put some water in the base of the humidity dome or leave that area dry and just mist the seedlings?

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Sounds like you have it figured out. I don’t put water in bottom, the moisture from the water you give plants should provide enough moisture in the dome.

Thanks, @Liljoe
One question - I’ve never used Rapid Rooters before. Once the seedling is established, do I water the Rapid Rooters every few days or just mist the plants twice a day like I do in soil?

I have never used rapid rooters but im sure they r like any other way, mist acouple times a day and just dnt let rapid rooters dry out. Or use a humidity dome for abit.

@Liljoe Was wondering if I am only germinating 2 seeds in a large germinating dome concerned that there won’t be enough humidity for the little ones in such a big dome. Do you think in this case I should be adding water in the bottom tray? Please others chime in also. Thanks

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It is possible if the dome is too big, do u have a humidity meter in ur dome? U can also lift your seedlings up higher in the dome, more humidity and warmer in the top part. I like using hockey pucks for that, each puck is 1inch and they are nice and small. And yes adding abit of water should help abit also

@Liljoe Yes I did a little test with a meter in the dome but no water. Humidity was too low I felt. Will give it another try with water in the bottom tray. Thanks
Today with the lights off and humidifiers still running with fans I had a shocking RH of 80% Heck might as well just put the dome in the tent seeing how I have no plants in there yet. Guessing I am going to have to MH light really really high or put the ballast on the lowest setting?

Put water in tray, dome back on and temp is 86 degree and RH is 48% Done everything to get higher but to no avail. Is this normal with having no seeds in the dome? I am thinking not
@Bubblehead @Liljoe @moneypit @JD419WhyWait @MattyBear @TDubWilly @garrigan62 @SlowOldGuy @dbrn32

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Looks like my problem was the heating mat. Sorry everyone the mat was working when i unboxed it last week. Thought it was a little low with heat but thought maybe that was normal


Well done to catch it without seeds!

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Rite on, glad u got it figured out. I keep my lights on top of dome to keep heat up

Humidity is usually at 90% inside dome and 78-80F

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I do have a Clone tent I got with a T5 grow light fixture. But haven’t done anything with it yet. Having one headache now with the 3 x 5 by 7 tent and don’t need another one. Lol. Like your setup @Liljoe

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