Seed Starting - Soil Heat Ideas?

Hi all - gearing up to start seeds. We have an indoor setup with plenty of space and grow lights. Hoping I can gather some wisdom on some easy/cheap/reuse ways to heat up the soil.  Key for me is safe, low energy use and cheap. I'm considering rope lights but hoping someone has a more creative and environmentally friendly alternative than lead coated plastic gook!  

I start my seeds on a rack above heat lights that are already in use for a couple of reptile enclosures. I've also used reptile heat mats in the past as well. I cant imagine heat mats are much more expensive than rope lights and prob much more effective.

The "real" germination mats, though expensive, are good and safe. Waterproof, and with a thermostat, they take a lot of worry and frustration out of figuring out a cobbled together setup. One thermostat can control multiple daisy-chained mats. They are also sized in multiples of 10x20 inch trays, which is nice.

We have also tried electric blankets, with plastic sheeting to keep them dry. They work, but have only a number scale (1,2,3,...7,8.) not a thermostat so hard to adjust temperature, and also have an "auto-shut-off" safety feature, requiring a power switch cycling to reset them every 8 hours. (a real drag if that means a before bed trip to the greenhouse in the cold...)

I have not tried, but have heard of gutter heat tape in rows for benchtop heating. Usually foam insulation board or Reflectix bubble/foil insulation covered with sand to hold the wires and spread the heat. A similar setup is possible with hot water in plastic tubing, like a radiant floor heat system.

For years I used a regular heating pad, like one would use for sore back muscles and the like. I set it on low, and while it worked and did the job, it is small at approximately a little more than half the size of a 10x20 cell tray. Even though I used a humidity dome, thus trapping some of the heat, the cells directly over the heating pad always seem to germinate faster than those not over the pad. This was one downside to the small pad, but I just moved the cell tray around to try and keep things heating evenly. Another downside is mine isn't waterproof, and inevitably I spill water on it. This winter, I took the plunge and bought a 20x48 seedling heat mat, which allows me to warm four 10x20 cell trays, and it's waterproof.

These are great points! Maybe I'll take the plunge for a germination mat. Any recommendations on brand if I head in that direction? Anything I should be wary of or look out for regarding quality/efficiency?

In all honesty I looked at the various DIY versions of heat mats.. I didn't think it warranted my efforts personally. For 11 bucks on amazon, mine has hung in for at least two years running for about 2 months. (I start a LOOOOT of things lol)
11 dollars. works for me. mine does one tray of 50 cells at a time. (the rapid rooter tray is my all time fave. it's SO much easier and seems to work way better than conventional starter mix and water. could be me though. it is pricy but definitely worth it if you intend to do some particularly finicky plants. my vervain and ashwaghanda seeds are laughing at me right now...)
the brand I have is called Seedfactor. if you look it up on amazon it should pop up for 10.99. good luck!

I've been wanting a seed starting heating mat, but I live in a 220 V country where these are not a thing, and travel annually to a 110 V country where they are. On amazon.in I can find one offered but it seems to be shipped from Canada, and I asked if it works on 220 V but didn't get a reply. I suspect it would be unsafe to use on 220V? Do I have to somehow get one from Europe or some other cold-weather 220 V country?

I do have an "electric blanket" (actually a mattress pad) so I think I'll use that this coming spring. Can anyone please detail how they waterproofed such a set up? Thanks!

Now granted I do a LOT of flats b/c I grow for a CSA and market, but another farmer gave me a tip I use every year. Buy an air mattress, you can get them pretty cheap at a sporting goods store. Put a waterbed heater under it. fill halfway with water, and you have a nice BIG heating mat.

I'm starting outside in an unheated small greenhouse, on a table made with plywood. I created a frame that stands about a foot tall to cover with frost cloth in the event it really gets cold at night, too. Even heat till seeds are up is best in general.

Rebecca Norman wrote:I've been wanting a seed starting heating mat, but I live in a 220 V country where these are not a thing, and travel annually to a 110 V country where they are. On amazon.in I can find one offered but it seems to be shipped from Canada, and I asked if it works on 220 V but didn't get a reply. I suspect it would be unsafe to use on 220V? Do I have to somehow get one from Europe or some other cold-weather 220 V country?

I do have an "electric blanket" (actually a mattress pad) so I think I'll use that this coming spring. Can anyone please detail how they waterproofed such a set up? Thanks!

Hi Rebecca,

You should be able to get a transformer 2:1 to step the voltage down or alternatively a 1:1 transformer wired as a step down auto transformer.  They only need to be a 100W or so and thus should not cost a fortune.  If you can only find a 1:1 I can tell you how to wire it to do the job.

I looked up one on Amazon and found this 200W version for around $18 :

https://www.amazon.com/Simran-SMF-200-Converter-International-BlackBerry/dp/B000W9DJ1Q/ref=pd_sbs_23_t_0/143-0607675-9410147?_encoding=UTF8&pd_rd_i=B000W9DJ1Q&pd_rd_r=e295aa29-a9ba-493a-b90d-9fde49c00ba4&pd_rd_w=fmOzM&pd_rd_wg=elJU8&pf_rd_p=5cfcfe89-300f-47d2-b1ad-a4e27203a02a&pf_rd_r=63MNY0FP0KZ5GS69MXJH&psc=1&refRID=63MNY0FP0KZ5GS69MXJH

Sincerely,

Ralph

You all have made me smarter and Rebecca, my world just got a whole lot bigger! 220v at 10,500 feet! I've seen the Q&A regarding the need for a solution to this and never made the connection. Amazing, Ralph has the right idea.

Well, thread has been helpful and has convinced me that spending a little on the seed mats will probably pay dividends. (Plus I'm worn out on trying to find a way to cobble together a diy solution). I ordered a couple of mats and a thermostat and will post feedback on how they work. Thanks for all the help!

Wow, over 25 years an I never needed a step-down transformer so I forgot about them, but I think you're right, that may be the solution! Thanks!

My question would be, do you need it? Under lights the soil will be pretty warm anyway, I would worry about getting it too hot if you were going to heat it more. I start around 10000 seeds each year inside under lights and the area stays over somewhere between 20 and 25C depending on room temperature without any extra heating. Tomatoes take around 3 days to germinate at those temperatures.

Skandi - what kind of lights do you use? Our setup is fluorescent and LED so not much heat is produced. I thought about adding an incandescent bulb or two and covering the seed area with plastic to retain the heat. This is a pivotal year for our gardens and business so I didn't want to risk losing our seed or getting a late start.

If you're using lights anyway, on top of the fridge is usually warm enough.

Marie Tedei wrote:Buy an air mattress, you can get them pretty cheap at a sporting goods store. Put a waterbed heater under it. fill halfway with water, and you have a nice BIG heating mat.

I never thought to add the air mattress and water. I like it, because you can get more flats on it. I have used a waterbed heater though. I used to put the probe onto or into the soil. That was before I realized wet soil conducts heat better than dry soil. That lesson cost me a melted flat and a few days of wondering if I was smart enough to be using electricity unsupervised. Now I lay the probe right on the mat and put the flat on top. Works fine like that.

" That lesson cost me a melted flat and a few days of wondering if I was smart enough to be using electricity unsupervised."

LOL well, I've melted flats out in the sun, myself. ;)