Model # VHMDT

Internet #205854521

Viagrow 20.5 in. x 8.5 in. Single Tray Heat Mat with Thermostat


20.5 in. x 8.5 in. Single Tray Heat Mat with Thermostat

$5999 /each
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Frequently Bought Together

Product Overview

The Viagrow Seedling Heat Mat and Viagrow Seedling Heat Mat Thermostat combination pack are the best and most affordable way to guarantee that all of your precious seedlings get off to the best and fastest start possible. The Viagrow Seedling Heat Mat and Viagrow Seedling Heat Mat Thermostat are easy to use; simply place your heat mat on a flat, dry surface underneath your seedlings, plug your Viagrow Heat Mat into the thermostat and place the temperature probe in your germination plug, soil, or tray and set your desired temperature. The Viagrow heat mat and thermostat will automatically regulate the temperature of your delicate germinating plants. For best germination results, place a propagation dome (VTD300) over your seedling tray and keep them under T5 fluorescent lighting. Direct sunlight or high HID lights may be too intense for seedlings. As a general guideline, seedling and clones grow best with temperatures of 70-80°F and humidity range of 50%-60%. Please be sure to research your particular plant as temperature and humidity requirements vary for different species and hybrids fluorescent lighting. Direct sunlight or high HID lights may be too intense for seedlings. As a general guideline, seedling and clones grow best with temperatures of 70-80°F and humidity range of 50%-60%. Please be sure to research your particular plant as temperature and humidity requirements vary for different species and hybrids.

  • Simple installation - just plug in, place in soil and set temperature
  • Warms root area 10-20 above room temperature
  • Speeds germination and encourages strong root growth
  • Fits snugly under a standard size seed tray
  • High quality, water resistant construction
  • May be used with a compatible thermostat for temperature control
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Info & Guides

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Customer Questions & Answers

Whats the highest temperature on the mat thermostat

Asked by: Lenny
Box says 108F
Answered by: Buzz
Date published: 2016-07-12
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Customer Reviews

20.5 in. x 8.5 in. Single Tray Heat Mat with Thermostat is rated 4.2 out of 5 by 6.
Rated 3 out of 5 by from I’m not sure if the problem is the mat, or the thermostat, or expectations of performance I had originally written up this review as you see below the dashed line, but a realization came to me as I was about to post it, and I want to put that part up top (see the next paragraph), even though it’s one of the last things I wrote: --- I think there’s a problem with expectations here. If you buy the mat by itself, it only claims that it “warms root area 10-20 degrees above room temperature”. The current (as of writing this review) product listing for both the mat/thermostat combo, and the thermostat solo don’t make any claims on what tempteratures it can coax out of this mat. So, perhaps with *this* mat, trying to match the expectations printed on the *thermostat* were unrealistic. Perhaps not. There’s nothing that came with either that makes any mention of what limitations they might have when used together (which in an of itself is, in my mind, a failing on the part of the manufacturer). I don’t currently have the extra time/brain to have a conversation with Viagrow tech support, but perhaps if anything I’ve written gives you pause on buying this because of limitations, *you* might want to make that call :-) ================ It might help to know before reading this review that I got this mat for more than just starting seedlings. I also wanted to see if it could help me with a couple of kitchen tasks, namely rising bread dough and making yogurt (both things that require keeping a steady temperature in a small area for anywhere from 1-8 hours). I’m also going to mention up front that while the mat itself is branded Viagrow, the thermostat is just some generic “Made in China” unit (not even a brandname on the box or unit). Take that for what you will. And, in addition, when changing the set temperature, you can’t hold in the button to have it fast advance; you have to press it once for each degree change. I decided to test the mat and provided thermostat (which I’ll refer to in the review as PT) for my kitchen uses first, to see how it handled the most extreme temperature I was going to use it for (108F). The box claims PT can do “precise temperature control 68-108 degrees F”. I actually set the desired temp for 107, as the manual says that PT will go into an “automatic safety shut-off” if the probe reads 108 degrees F. I then put PT’s probe on the mat, put a box over the whole setup (to avoid cooler air from throwing off the readings), and left it alone. The manual says that it can take up to 5 hours to reach the desired temperature. NOTE: this initial testing took place in a kitchen that was ~68-70F. More than 5 hours later, PT’s readout was still a few degrees shy of 100F. On the thought that the mat was losing temp to the table under it, i threw a piece of cardboard under it. Within an hour or so the temp had risen to (and was holding steady around) 105-106. I had another remote thermometer (“RT”) in the box (atop a shot glass), and it was reading 108. So at this point it *seemed* like it could hold the high end of the temperature range, as long as it was insulated from below. HOWEVER. I then tried this with something on the mat itself (in this case, a yogurt tub filled with millk preheated to 110F). Uncovering the mat and putting the tub in place caused PT’s reading to drop to 87F. I covered everything back up, and when I checked everything over an hour later PT was *down* to 85F! BUT: RT (this time on the mat itself) still claimed it was 108F. I readjusted PT onto a different part of the mat, and it (very slowly) started to go up. After 10 minutes, PT only read ~98F, and RT read 109F (making me wonder if PT was trying to get the mat to heat *more*, instead of just reading an already existing temperature). I confirmed temps with yet a 3rd digital thermometer, and it confirmed that PT was reading significantly low. After giving it more time to see if this disparity changed (it didn’t), i shut off the heat mat. I’m not sure what the *gardening* use of having the mat hold a temperature of > 100F is, but I wouldn’t trust this one to accomplish that any more than it did with the milk. Before testing a lower temperature using PT, I decided to try the mat by itself next. The packaging on the mat states that it “warms root area 10-20 degrees above room temperature”. Obviously I wasn’t using PT to measure temperature on this one, just RT and CT. Room temp was 69.8F. After an hour, RT (on the mat) read 96.0 F, CT (reading a few inches above the mat) read 87F. So *that* seemed to lend some credence to the temperature claims for the mat by itself (but without anything on it). I did *not* pursue more mat-only testing because i got the combo specifically to use the provided thermostat. I only did this to get a rough idea how the mat was functioning on its own. I then set it up with a seedling try (but no cover) on a rack in the basement (air temp 55F), with a piece of wood between the shelf and the mat. I set PT to reach 80F, stuck the probe deep into one of the cells full of moist soil, and left it overnight. The next morning, PT read 60.9F. So not real effective that way. I then went out and got a seedling tray with a cover, set *that* up, and put the probe thru the cover and into one of the cells full of soil. This time I put a thick piece of cardboard between the shelf and the wood (for extra insulation), *then* the heating mat, then the seedling tray. I left the thermostat set for 80F. When it started the soil read 50.4 (air temp was still ~55). After 1-2 hours it read ~69F (so much better than the uncovered test). After another 3 hours, however, it only read 69.7F. In other words, it didn’t really change in those 3 hours. So it looked like ~10F shy of target was as close as it was going to get. (I put PT in another cell to confirm; that one read 68). To confirm that PT was reading ok, I stuck CT into a couple of cells. It read 72-74F. However, I left it overnight, and in the morning PT said it was 76.9F. So, yay? BUT WAIT: For the record, PT’s manual says “The Digital Heat Mat is designed to achieve the desired heat temperature within 5 hours. If it takes longer than 5 hours, or if the mat runs for longer than 5 hours, desired temperatures are not being reached. To conserve power and increase the mat’s effectiveness, move the mat to a more insulated surface. You can also add a humidity dome to cover the seedling tray, which aides [sic] in heat retention.” So, according to it’s own instructions, the fact that it took well longer than 5 hours to even get to 76.9F (when set for 80) is apparently a bad thing (?). And I already had used both the insulated surface and the humidity dome when running this test. I gave it one more go with the thermostat (same setup) set to 70F. I came back well over 5 hours later and (this time) it was actually close to the temp i set for it (the PT was reading somewhere between 69.3 and 70.6 - which is another observation I have: even when you would expect a stable temperature, the reading on PT is usually bouncing around within a ~1.5 degree range as you stand there watching it.) So. My conclusion: (ASSUMING THE TEMP CLAIMS ON THE THERMOSTAT BOX ARE MEANT TO APPLY TO THIS HEAT MAT IT’S PAIRED WITH) it doesn’t really do what it says it can do. Let’s ignore for a minute that my initial testing was at the top of the stated temperature range. If I ask it for 80 (*well* within it’s stated “68-108F” range), and 5 hours later it still hasn’t exceeded 70F (using exactly the kind of enviroment the instructions say are optimal (e,g, a covered seeding tray and something insulating the mat from below)), color me unimpressed. The fact that it finally succeeded at acheiving 70F doesn’t impress me. That’s only 2 degrees over the *bottom* of the stated operating range, and only 15 degrees over the ambient temperature where I was testing. Don’t get me wrong: I’ll use it, but I’ll do so in full knowledge of its limitations, and I’ll work around them.
Date published: 2016-03-08
Rated 5 out of 5 by from Automatically regulates the temperature of your delicate germinating plants. The Viagrow Seedling Heat Mat with Thermostat provides a tremendous service to home gardeners by automatically regulating the temperature of delicate germinating seeds and plants on those extra chilly late winter and early spring mornings. The mats are easy to set up and use. I just plug them in, set the temperature and place the probe in the soil of the plant tray. I try to use a tent or dome over the seedlings to help insure constant air temperature and humidity ranges. Keep a close watch on the soil moisture content because the warmer temperatures tend to accelerate evaporation. I am having excellent results with several small citrus trees I’ve started and allow that the Viagrow heat mats are a big part of my success.
Date published: 2016-04-07
Rated 4 out of 5 by from Seedling Heat Mat This mat is very easy to install. You simply plug in and set thermostat. The temperature will go about 10-20 degrees above room temperature. It does take a little while to heat, not like plugging in a heating pad. It will heat nicely and I have had success germinating. Each plant will require research for best results. The mat is durable and waterproof.
Date published: 2016-05-10
Rated 5 out of 5 by from works great I use this to keep my kombucha culture at the 78 degrees it likes. Its doing a great job. I probably have to get another one for my seedlings next spring.
Date published: 2016-04-19
Rated 4 out of 5 by from Seems like a good heater I was looking at this through the Seeds program site last year before winter, didn't realize it was for starting plants indoors in early spring while it was still cold outside. I was looking for a heat mat with a thermostat to boot under my boot tray in the garage. Was getting tired of putting on boots that were still half-froze up with snow and ice in the winter from clearing the driveway. It arrived late (manufacturer shipping issue I guess), but I was able to test it with some ice cubes in the plastic boot tray. Works fine for that from all appearances. However, now that I know what it is for, and seeing that most of the 'kits' you can buy to start seedlings and such indoors are about the right size for this mat to fit under, I might give that a go early next spring when we finally try a garden at this house (we've only libed here a couple years now). Temp control seems accurate enough, and Ive checked it with an infrared thermometer. Miight get another is the seed starter kits work like I think they should. Then I can get a good jump start on the garden the year after. Unit seems sturdy enough, not too bad on the electric bill, and the mat is rubber coated and pretty flexible (came rolled up in a small box when delivered).
Date published: 2016-07-11
Rated 4 out of 5 by from Great for colder climates This mat is fantastic. I live in the Pacific Northwest, where it stays cool at night well into April and May, and we don't get too many sunny days. In previous years, I have had difficulties sewing seeds indoors for this reason. I was attracted to this mat because one of the tricks I have done in previous years is put the seedling trays on top of a heating duct vent, which I found the heat to promote quicker germination. This mat works very well, and keeps a consistent temperature. It has a temperature sensor with a suction cup, which is easily attached to the inside of a plastic greenhouse dome. I was able to place it in a bright location, so when the sun does shine, the small seedling leaves can get some light along with the heat. I envision this working great in a small enclosed greenhouse to keep it hot and humid--maybe next year, but this year I was able to use it with the tray and plastic dome. You can adjust the mat to different temperatures based on the recommended germination temperature for your seedling species. Some plants require a consistent temperature above 60 degrees, so this is great for that. The only complaint I have about this product is that it works too well. At the end of the day, I'd often find my soil had completely dried out from the consistent heat, and I'd have to consistently water the tray at morning and night. Perhaps in the future I will keep the heat on just during the day, to emulate a more natural environment. The consistent heat was not an issue for my garlic plant, which was in considerably more soil than the seedling tray. It held the moisture throughout the day and grew quite quickly with the mat's heat. Maybe I will use a thicker seedling tray next year.
Date published: 2016-05-14
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