Heating mat question

I usually have 8 flats at one time under lights- I start a lot extra of everything to gift my neightbors- I found that financially and plug space wise it was not practical to have heat mats. We had a bad cold snap and my plant room temperature dropped to around 65. I put a small electric heater in there and within hours the temp rose to about 74- and that was with running the heater on the economy setting. I have plastic domes over germinating seeds which keeps the humidity high and run the ceiling fan to circulate the air.

My tomatoes and herbs came up in 5 days and today I see the peppers and eggplant peeking thru.

This may be another solution to those who do not have heating mats.

Well the double heat mat I have only draws 45 watts so It's cheaper that using an incandescent light.

Doug

We've used heat mats (with temp controls on the mat) for a number of years without any issues on the plants. We've used both regular and self watering flats. The flats are all in the basement. Until recently we've only put the seeds that have a higher germination temp on the heat mats. Last winter was cold and so more items went on the mats than usual. I haven't noticed any negative reaction because of the heat mats. We let the heater mats run 24/7 until the basement or outside is warm enough for the plants.

I'm not a big fan of portable electrical space heaters being left running unattended as they are a high risk in causing fires. So please make sure that anyone using them does not leave them unattended.

Much easier on my finances to heat the soil in trays and pots than to heat a whole greenhouse. Like Susan I've never had any troubles with heat mats but there might be a small learning curve for some folks. Fortunately I LOVE thermometers and am always taking the temperature somewhere. (Heck, I even have thermometers nailed to trees out in the woods, just because!) *grin

Shoe

Well, my soil heating method works for me! I BROKE LAST YEAR'S GERMINATION TIME RECORD!

Two flats popped last night (Mule Team and Black Krims, 3 days), and 3 more popped overnight (Russian Rose, Momotaro, Virginia Sweets, ~ 84 hours). I sowed seeds on Monday evening, January 2, 2012. Waiting on the Perfect Purples...

They've all been shoved under the fluorescent shop lights, which are laying on top of the flats.

Last year I had 6 flats come up on a Sunday, 6 days after sowing, and all at once.



This message was edited Jan 6, 2012 12:37 PM

We seem to have a similar need to know temp affliction at our house. We have a temp sensor on the front of the house, in the backyard, on a window, and in the attic. A combination of remote and local sensors, a mobile temp sensor, and a direct link to weather.com (and a couple of others) on the cell. No tree temps yet. :-)

That is sooooooooooo funny! LOL!

The funny part is the DH's family is from VA and he's a redhead. I was wondering as I was writting the post above if he possibly related to Shoe as they have a similar interest in the temp. The DH also has his own soil temp probe. :-)

The attic temp also transmits humidity.

Heheheheh, yey for Susan's hubby! Another temperature freak! And yes, got the soil probe's, too. And one of them, a digital, doubles as a cookin/meat thermometer so I don't overcook my chicken and steaks! :>) At one point in time local friends "worried" about me, with thermometers everywhere: old mailpouch thermometer outside the Shoffice, huge dial thermometer, on another wall, a combo thermometer/hygrometer/humidity meter elsewhere, wireless thermometers in the greenhouse, under the overhang where the tractors are parked. And of course I'm sure something is hanging in the chicken coop, too! :>)

GG, congrats on your tomatoes declaring! You're on your way now!

Shoe (wondering how cold it'll get tonight) *grin

OK Shoe tell us how bad you really got it. How many rain gauges do you have?????

Crackin' up in KY..

Sorry. Neglected to mention the numberous cooking temperature sensors the DH has. One electronic remote cooking sensor, one candy thermometer, one what temp is the fridge, one what temp is the oven, and one old style what temp is the meat.

We don't have any chicken coups or tractors so I'm sure about those. But I never thought to ask what he has at the office. And thinking about the garage I remembered the last car we bought (his choice) has a ambient temperature sensor and weather band radio.

I'm also thinking all those years of marriage and I never realized there was a temperature obsession.

DH had a number of rain gauges but they kept getting pounded by all that Kansas hail and knocked over by the local varmits (dog, cats, woodchuck, etc). I think he's given up on gauges in the yard as I can't remember any in the yard right now. However, he can get all that information locally now on the web so maybe he's just outsourcing the job.

"just outsourcing the job". Great idea, Susan!

I'll see your last post and raise ya...

...One oven thermometer which also travels out to the smoker grill from time to time; two weather radios, one with a built-in digital thermometer plus a pull-out compass on top; a plastic chicken weathervane with the spinning anemometer/broken rain gauge/thermometer; and speaking of rain gauges, in addition to the broken one I have 3 more...two "go lookats" and one wireless. Oh yeh, and a pie pan on the mat where I sometimes overhead water the potted perennials, judging the water amount according to the content of the pie pan. Er, does that count? *grin

Shoe (who also has five online weather pages saved to his favorites and see is it now 50º in Doug's town, 40º where Susan is, and GymGirl is suffering from or enjoying a temp of 66º!)

Happy Day, All!

She looked out the window this morning and saw, yet, another sprouting broccoli head, and she is DEFINITELY suffering!!!

Aaaaarrrrgggghhhh!

God, PLEZ send some 45-50 degree weather to Houston for eight weeks!

Linda

GG what's with the broccoli anguish?

Balmy 50 degrees here. Was suppose to get to 60 today.

Already counted the traveling meat thermometer. 4 weather band radios not including the car. Two are gifts from his parents as we do get a lot of tornadoes. Most all of the radios obnoxiously beep/buzz for everything and not just tornado alerts. I think he has a phone app that you can set for what you want it to sounds on. The phone app in not counted above.

Are you counting water pans in the yard? Because there are multi water pans in the yard for the dog, birds, and butterflies. Never occur to me he might be monitoring the amount of rain water via the watering pans.

No spinning anemometers but we can get that info on-line from the local weather monitoring station a couple of blocks away at the golf course.

BTW - He has seperate multiple apps (phone & PC) for the weather. Not just weather pages. :-)

Heheheh, you're killin' me, Susan! :>)

Next thing ya know we'll be having "weather roundups" for DGers.

Go pick that broc head, Linda. At least it'll kick in some side shoots to form, eh?

Shoe

By time I got outside, there were cute little bees buzzing all over those broccoli sprouts like it was Christmas day in the beehive.

And, since I'm learning to live in harmony with the wildlife, I figured they could enjoy it. Maybe they'll return the favor at tomato pollinating time -- not that I need them. My crosswinds did all my pollination last season.

Best harvest ever!

Linda

Temperature fetishists: what's funny about that?!? It makes total sense to me, inquiring minds want to know!

I would love to have remote-monitoring / recording thermometers for my compost heap and future solar cold frames and greenhouses. All it would take is a link to my PC's wireless network. Of course that should drive motorized vents and maybe shades, fans and electric heaters ... programable alarms that would send text msgs to my cell phone ...

interface the watering system to rain gauges ... plus maybe a motion sensor so I could water any cats that think my raised beds are catboxes.


>> Opening the top from time to time to allow an air exchange and excess moisture out is necessary

Hmm, "from time to time"! Leave it closed to keep the heat in MOST of the time, and vent it only occasionally to deter fungus. I hadn;t thoguht of that, it sounds smart.

>> styrofoam Grape containers from our Winco store, and plan to use them as perimeter insulation for my seed flats

"Perimeter insulation" for seed trays: I like it!

>> a small electric heater

I never thought of that, assuming it was too expensive.
What is the cost of 8 heat mats? Maybe $160?
At 20 cents per kilowat-hour, that would buy 800 KW-HR.

If a small electric heater is 800 watts that would run it for 1,000 hours of ON time.

Say it only runs an average of 10% the time, all day, to hold temperature.

That's 10,000 hours or 417 days or 60 weeks. If the heated part of the seed-starting season is 6 whole weeks long, the pay-back period for 8 heat mats might be 10 years or more. Maybe more.

It looks as if commerical heat mats are a huge capital investment compared to the surprisingly small recurring cost for electricity to just heat a small growing room!

Hunnh!

And if you had some fabric to make a tent around your seed shelving, I bet the heater would only run 5% of the time, like right after you opened the tent to look at them. Maybe a drywall enclosure on two sides and above, but now you're puttting tens of dollars into buying drywall. One plus is that drywall is fire retardent, so if the heater shorts out, the scorch will be contained.

Prohably the best bargain would be way to spread 1-2 heat mats over multiple trays, raised each tray 5-10 degrees above ambient. Then you could lower the setpoint for the seed-shelf-tent by 5-10 degrees.

No, the best bargain would be a tent or drywall around the seed shelves, positioned over a heating vent. That would keep the seeds 10-20 degrees warmer than the rest of your house, but the heat would still escape the tent and keep you as warm as it would have anyway.

But now you can keep your whole house at 50F, oh boy, think how much electricity that will save! Enough to pay for another rack of shelving and lights!

Rick, you gots too much time on your hands! :)

Waaaaaaaay too much time.

I must admit, though, that Rick is pretty entertaining! :-)

Like your thinking Rick, foung it would cost me about $86. to buy 4 heat mats plus then you would need a temp guage to keep from cooking your seedlings plus having to PLUG in 4 more things- I bought a small elecric heater which is on its own outlet and run it at night on economy setting. With the door to my plant room shut it raises the night air temp by about 8 d. then with all the florescents on during the day it is quite toasty there. I have had excellent germenation this year with this method, my tomatoes had their first leaves in 6 days.

Way to go , Cornish2175!

>> With the door to my plant room shut

I think that is the key to any heat-managment issue. Contain the heat where you want it, and then size the heater to the space.

I just saw a heat mat for $60 in the Pricey Parks catalog. 23" x 15". I would laugh uproariously, but they mention a chrome wire cage to allow air circulation. With no insulation! So the heat will just dump straight out into your room and the soil will still be room temperature. What a waste!

Of course, you could buy a $25 equivalent mat and then bring a wire rack home from Goodwill for $2, maybe folded newspapers for insulation, saving $33 or 165 KW-hrs of electricty!

Or skip the mat and spend the whole $60 on power for a small space heater, closing the door at night.
.

I am enjoying this thread.

Rick - You are missing the cost of the gas or electric heater in the cost estimate above.

I found my heaters on sale at Lowes for $38. + tax. Granted, they are small heaters and would not heat my large living area but perfect for the sunroom and the plant room. I have not seen a significant raise in the electric bill but since we heat a 16' swim spa year round! We have been lucky this year with the cold- only had 1 night that temps dipped below 30 but mostly the temps have stayed 40-50 at night then spiking to 70-80s during the day. Its a rollercoaster and my poor plants in the ground are very confused.

As long as we're daydreaming, I can immediately foresee one problem with this arrangement: it would be very difficult to keep your media from drying out and killing the seedlings. Cold air is not capable of carrying as much water as warm air, so even at saturation the absolute humidity is low. Heating it causes the relative humidity to drop. Warm moving dry air evaporates moisture from porous growing media very quickly.

Supplementing moisture by adding a humidifier to the equation might help - but it's one more thing to keep track of. Every time the forced air stops, the humidity inside the drywall enclosure will immediately skyrocket. Ever seen mold and mildew growing in drywall? I have. You don't want to. (You could ask the survivors of Katrina about molds in drywall).

After some 40+ years of trying different growing arrangements, I've learned the KISS principal definitely applies. There's a reason so many people use heating mats despite the up-front cost.

-Rich

>> Rick - You are missing the cost of the gas or electric heater in the cost estimate above

I am assuming that you already have a small space heater, but, true, that is also a "capital expense". Similarly, it doesn;t cost extra to shut the door, and the furnace or wtaer heater was going to be running the same amount anyway.

maybe there are two different ways to comapre schemes: "fairly", where you include all costs, or "incrementally", where a person only looks at what she or he needs to add to pre-existing expenses to adopt that scheme.

Thus, for someone who already has plenty of heat mats for all their trays, "heat mats" are a clear winner.

For someone with no heat mat, but with a small, warm room they can isolate plus any random small extra space-heat source, that is a clear winner.

I'm a big fan of insulating trays if you use heat mats, but, realistically, how many years would you need to run a 29 Watt heat mat to pay back the cost of a sheet of drywall? I forget how much the 4x8' sheets cost. I bought 2, 2'x2' squares for around $3-4 each. To justify my favorite scheme, I would have to say that insulation lets a low-powered mat raise the temperatue higher, or warm 2 trays instead of one.

I was just pointing out that a cost evaluation would have included the cost of the heaters. We don't own portable heaters as I know them to be a fire hazard. I tend to review what the safety and cost issues are for a project. Our basement is heated. We choose to keep the basement temperature lower in the winter and higher in the summer. The tradeoff is that we use matt heaters until the plants go outside.

I'm assuming the issue about the drywall is not the cost of the drywall replacement but the cost of the clean-up (or tear-down) if black mold becomes an issue. Black mold is considered a hazardous item and sometimes the house involved is condemned.


Hope this helps clarify.

Good points. I lived for a while in a very humid basement in New Jersey that was saturated with mold. Not pleasant. I think that is a bigger consideration if the whole germinating room is sealed and humid. If an insulating tent is put around the trays, it seems that only the tent would be prone to collecting moisture and mold.

Maybe the mold problem is mitigated by the fact that most people would only start seeds a few months per year, and the rest of the time, the warmer room would tend to bake itself dry.

Managing humidity in an enclosed space with a lot of moist soil is necessary. Venting the space freely means you'll have to replace the heat lost. If the insulating walls are cooler than the soil, (as they would have to be), humidity will tend to condense on the walls' inner surface.

On the other hand, the walls will be warmer than the surrounding space, so humidity will tend to evaporate from the walls outer surface. How would tjat work in practice? I'm not sure, but if I do this, I will paint the inner surface of the walls with waterproof paint or line them with well-sealed plastic.

Maybe, for small spaces or a well-insulated grow space, there would be some appliance that produced enough heat to warm the space without excessive fire hazard. I'm thinking of 100-200 watts, like a few light bulbs or maybe an iron. I know that there are baseboard heaters designed to heat rooms, some portable and some designed to be built-in, and I thought they were sarfe to run unattended.

Soil-heating mats are one extreme of size: 27 or 40-50 Watts heating just a few square feet 3" deep. Very power-efficient if you can afford the heating mats and thermostats.

Heating an entire greenhouse, or your whole house, is the other extreme.

Heating one small room or a "tent" around several trays would be a comprpmise between start-up costs and ongoing expense.

Oh I don't know Corey. I have a lean-to type greenhouse with windows on three sides and a clear polycarbonate roof. I put bubble wrap between the ceiling joists in winter and make sure all my vents are covered by 2-3" thick foam stapled in place. I use an oil filled radiator heater ~$80 at Lowes that I set to come on if the temps drop below 50 and it is doing quite well at a very reasonable cost. Makes a great place to escape to in the winter to drink a few beers and listen to the blues too!!! I think it gets used more in cooler weather than any other time! I keep a lot of plants in there not so much to propagate yet but to just see if I can keep them alive during the winter. I have Amaryllis blooming, Boston Ferns showing new growth, a Poinsettia I've had for about 4 years now. It's fun just to go up there and play around. (No I never had a playhouse as a kid!!)

Doug

That sounds like a great spot, and better-insulated than most.

Wish I could join you there, I'd bring the beer!

Corey

Not Oly I hope!!!

I never beard of Oly Beer ("Olympia"?) so I looked it up. Given all the really good microbrews around here, I'm surprised no one tried to revoke their right to use that name. It sound like Rolling Rock from Back East: like half-bland American lager and half water. Yuck! I bet slugs would like it.

Maybe Full Sail Amber or anything from Deschutes or Bridgeport Brewing.

Olympia and Rainier was what I drank when I was stationed on Whidbey Island in the late 70's. Microbreweries were non-existant back then. Still have a lot of fond memories of the PNW. Can you get beer from Utah breweries there? If so try to find Provo Girl Pilsner. We had it in New Mexico, Arizona and Utah back in April/May. Pretty good pilsner, but cannot get it here.

Pic from top of Mt Erie looking back towards Whidbey Island.

Doug


This message was edited Jan 14, 2012 9:24 AM

Rainier - the green death. :-) What we called it when we lived in the PNW many years ago. Harp, Guinness or Smithwicks these days.

With Mc in your name of course it has to be Irish beers!!!! I kinda like Fullers London Pride myself..

Doug

;-) We won't even start on the whiskey's......

>> Provo Girl Pilsner

If I see it ... I don't recall having seen a Utah brewry locally.

Corey

I finally broke down and purchased a heating mat and thermostat. With free shipping they were $50.94 which I thought was a good price.

http://www.amazon.com/gp/product/B000NZZG3S/ref=ox_ya_os_product
http://www.amazon.com/gp/product/B0001WV010/ref=ox_ya_os_product