Cheaper Heat Mat: improvised heat mat

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Cheaper Heat Mat

By Gymgirl
February 2, 2013

A heating pad set on low and placed underneath a cookie rack makes a great impromptu bottom-heat source for tomato, pepper and other seeds! Just set the tray on the mat until the seedlings germinate. Do NOT leave the pad on while you're away from home!

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Name: Rick Corey
Everett WA 98204 (Zone 8a)
Sunset Zone 5. Koppen Csb. Eco 2f
I helped beta test the first seed swap Plant and/or Seed Trader Seed Starter Region: Pacific Northwest Photo Contest Winner: 2014 Vegetable Grower
Avid Green Pages Reviewer Garden Ideas: Master Level Garden Sages I was one of the first 300 contributors to the plant database! I helped plan and beta test the plant database. Charter ATP Member
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RickCorey
Feb 1, 2013 6:21 PM CST
Great tip! I love the idea of a cookie rack as a "heat spreader! I've been looking for a suitable slab of sheet metal for a few years, but your idea should work better.

Maybe find a store that sells or "recycles" used appliances. They may have a stack of cheap wire shelving from ovens and old fridges that could not be fixed and have been cannibalized.

For any kind of heat, you can get twice as much heat from it if it sits on top of a good insulator. Wood would do, but wood has gotten expensive. "Sheet rock", a.k.a. drywall, a.k.a. gypsum board, is a great insulator, and is also fireproof. Lay down a 3/4" sheet or 1/2" sheet of drywall, then your mat, then the cookie rack, then something waterproof, THEN your trays of seedlings.

Assuming that you're spreading one heat mat over several trays, you might want to capture all the heat you can. Heat rises - that is, heat is lost to the air, and warm air rises, carrying away the heat.

If you can make some kind of tent over the whole stack trays and heat pads, the warm air will be trapped and your overall temperature gain will be much greater.

However, humidity will also be trapped and air circulation prevented. That will cause damping off and even mold. You'll have to strike a balance between heat efficiency and the required amount of air circulation. Maybe some deliberate vent holes or intermittent venting with a fan.
Name: Karen
Cincinnati, Oh (Zone 6a)
Forum moderator I was one of the first 300 contributors to the plant database! Cut Flowers Winter Sowing Charter ATP Member Seed Starter
Echinacea Plant and/or Seed Trader Region: Ohio Region: United States of America Butterflies Hummingbirder
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kqcrna
Feb 1, 2013 7:05 PM CST
Hey Linda! Good to see you. I thought you'd vaporized.

Karen
Name: woofie
NE WA (Zone 5a)
Charter ATP Member Garden Procrastinator Greenhouse Dragonflies Plays in the sandbox I was one of the first 300 contributors to the plant database!
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woofie
Feb 1, 2013 7:59 PM CST
Hey Rick, I do hope you're saving your bubble wrap. Works great for draping over flats to help hold in the heat overnight.....which helps cut down on my GH heating costs! (Of course, that only works if you already have humidity domes to keep the bubble wrap off the seedlings!)
Confidence is that feeling you have right before you do something really stupid.
Name: Karen
Cincinnati, Oh (Zone 6a)
Forum moderator I was one of the first 300 contributors to the plant database! Cut Flowers Winter Sowing Charter ATP Member Seed Starter
Echinacea Plant and/or Seed Trader Region: Ohio Region: United States of America Butterflies Hummingbirder
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kqcrna
Feb 1, 2013 8:50 PM CST
And you're leaving out a minor detail: you need to have a greenhouse.

K.
Name: Rick Corey
Everett WA 98204 (Zone 8a)
Sunset Zone 5. Koppen Csb. Eco 2f
I helped beta test the first seed swap Plant and/or Seed Trader Seed Starter Region: Pacific Northwest Photo Contest Winner: 2014 Vegetable Grower
Avid Green Pages Reviewer Garden Ideas: Master Level Garden Sages I was one of the first 300 contributors to the plant database! I helped plan and beta test the plant database. Charter ATP Member
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RickCorey
Feb 1, 2013 9:06 PM CST
I want a greenhouse!

I do save bubble wrap, and I should use it on the trays I put on my one heat mat. I don't have enough humidity domes, but I have plenty of 18" wide Saran Wrap, and min i-blind slats cut narrow enough to fit even in the little cells in a 128-cell plug tray.

Never do it the easy way if there is a cheaper "MY way"!

I worry that I don't have a soil thermometer ...

BTW, my bubble wrap is mostly anti-static bubble wrap. I have no fear of electrostatic damage to my seedlings!
Name: woofie
NE WA (Zone 5a)
Charter ATP Member Garden Procrastinator Greenhouse Dragonflies Plays in the sandbox I was one of the first 300 contributors to the plant database!
The WITWIT Badge I helped plan and beta test the plant database. Dog Lover Enjoys or suffers cold winters Container Gardener Seed Starter
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woofie
Feb 1, 2013 9:34 PM CST
Aw, Karen, you're just jealous! Hilarious!

Gee, Rick, you don't think a little *zap* might actually stimulate your seedlings to unprecedented growth? Green Grin!

I do like the idea of using the cookie racks, tho! I have some heat mats that I got cheap that really get too warm, and a cookie rack would work very nicely to moderate the heat! Think I'll look around at the goodwill for some spare racks!

And Rick, you can use the outdoor probe from one of those inexpensive indoor-outdoor thermometers to monitor soil temperatures. Our local hardware store has them for around $10. Smiling (At least that's what they USED to cost; sigh, haven't looked lately Rolling my eyes. )
Confidence is that feeling you have right before you do something really stupid.
Name: Rick Corey
Everett WA 98204 (Zone 8a)
Sunset Zone 5. Koppen Csb. Eco 2f
I helped beta test the first seed swap Plant and/or Seed Trader Seed Starter Region: Pacific Northwest Photo Contest Winner: 2014 Vegetable Grower
Avid Green Pages Reviewer Garden Ideas: Master Level Garden Sages I was one of the first 300 contributors to the plant database! I helped plan and beta test the plant database. Charter ATP Member
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RickCorey
Feb 1, 2013 10:01 PM CST
>> the outdoor probe from one of those inexpensive indoor-outdoor thermometers

AHHH! Good idea! I was going to steal the meat thermometer when Becky wasn't watching, but the difference between 75 and 90 is barely big enough to see with my eyes ... and probably off by 10-20 degrees!

>> Gee, Rick, you don't think a little *zap* might actually stimulate your seedlings to unprecedented growth?

(Gene Wilder / Young Frankenstein flashback)

"It's A L I I I I I I V E !!!!"
Name: Karen
Cincinnati, Oh (Zone 6a)
Forum moderator I was one of the first 300 contributors to the plant database! Cut Flowers Winter Sowing Charter ATP Member Seed Starter
Echinacea Plant and/or Seed Trader Region: Ohio Region: United States of America Butterflies Hummingbirder
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kqcrna
Feb 2, 2013 4:53 AM CST
Maybe so, Woofie! But with the storms and wind we get, just keeping a roof and siding on the house is challenging enough. I can't even imagine a small greenhouse weathering our conditions. That's why I've never seriously considered a greenhouse or even a coldframe.

Karen

Garden Ideas: Level 1
sewNsow
Feb 2, 2013 9:11 AM CST
I've used a heating pad practically forever in this drafty old house. Never thought to use a cooling rack,tho.Good thinking!
Name: Linda
Medina Co., TX (Zone 8a)
Charter ATP Member Salvias Herbs Bluebonnets Native Plants and Wildflowers Lover of wildlife (Raccoon badge)
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LindaTX8
Feb 2, 2013 9:30 AM CST
Most of the heating pads nowadays shut themselves off after a certain amount of time. Irritating, sometimes.
I would feel more optimistic about a bright future for man if he spent less time proving that he can outwit Nature and more time tasting her sweetness and respecting her seniority. E. B.White
Integrity can never be taken. It can only be given, and I wasn't going to give it up to these people. Gary Mowad
Name: Anne
Summerville, SC (Zone 8a)
Be a voice - not an echo!
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Xeramtheum
Feb 2, 2013 10:07 AM CST
Most excellent idea .. I use heating pads too! The newer digital heating pads have an auto shut off which can be a problem. I contacted all my kin and was able to get 2 more analog. I only turn mine on at night since I keep the house cold at night .. in the morning the temperature is usually in the upper 70's.

The best thermometers are darkroom thermometers ... they are not easy to find anymore since everything is digital. They are encased in glass and I usually bury one in a pot with dirt (you want it in the middle of the pot not touching the bottom) in the middle of my seed cups. You can probably find one online.

I use those extra large zip bags you can get at the dollar tree.


Thumb of 2013-02-02/Xeramtheum/2fc174
"We were all humans until race disconnected us, religion separated us, politics divided us and wealth classified us."

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Name: woofie
NE WA (Zone 5a)
Charter ATP Member Garden Procrastinator Greenhouse Dragonflies Plays in the sandbox I was one of the first 300 contributors to the plant database!
The WITWIT Badge I helped plan and beta test the plant database. Dog Lover Enjoys or suffers cold winters Container Gardener Seed Starter
Image
woofie
Feb 2, 2013 10:35 AM CST
I understand, Karen. A normal GH wouldn't survive the winds we get here, either! I remember reading a thread a while back where a guy had one of those small Harbor Freight greenhouses and the winds blew it over! Mine is really not a proper greenhouse, but it's a wood-framed building with clear siding.....and it's HEAVY!!!! And it has been a pain trying to add additional layers to insulate it, and the wood attracts wasps. Sigh, it's a pain, but our growing season is so short, it's really the only way I can grow a lot of the things I want. And DH insisted on getting it for me....I think he thought that would get the plants out of the house.... Rolling on the floor laughing Rolling on the floor laughing Rolling on the floor laughing Dreamer!!!
Confidence is that feeling you have right before you do something really stupid.
Name: Karen
Cincinnati, Oh (Zone 6a)
Forum moderator I was one of the first 300 contributors to the plant database! Cut Flowers Winter Sowing Charter ATP Member Seed Starter
Echinacea Plant and/or Seed Trader Region: Ohio Region: United States of America Butterflies Hummingbirder
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kqcrna
Feb 2, 2013 11:40 AM CST
Hilarious!
Surprisingly GREEN Pittsburgh (Zone 6a)
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Dog Lover Birds Plant and/or Seed Trader Bulbs Echinacea Irises
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crittergarden
Feb 2, 2013 4:14 PM CST
All the heating pads I've bought since the 90s have had shutoffs after an hour or less.
SHOW ME YOUR CRITTERS! I have a critter page over at Cubits. http://cubits.org/crittergarden/thread/view/73275/
Name: Anne
Summerville, SC (Zone 8a)
Be a voice - not an echo!
Plant and/or Seed Trader Enjoys or suffers cold winters Hybridizer Birds Seed Starter Cat Lover
Pollen collector Morning Glories Greenhouse Bookworm Garden Ideas: Master Level Garden Sages
Image
Xeramtheum
Feb 2, 2013 4:32 PM CST
If you or someone you know is electronically inclined you can usually find instructions on how to bypass the auto shut off on the net.
"We were all humans until race disconnected us, religion separated us, politics divided us and wealth classified us."

Unknown

Surprisingly GREEN Pittsburgh (Zone 6a)
Rabbit Keeper Bee Lover Cat Lover Lover of wildlife (Black bear badge) Butterflies Hummingbirder
Dog Lover Birds Plant and/or Seed Trader Bulbs Echinacea Irises
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crittergarden
Feb 3, 2013 6:04 AM CST
AHA!
SHOW ME YOUR CRITTERS! I have a critter page over at Cubits. http://cubits.org/crittergarden/thread/view/73275/
Name: Karen
Cincinnati, Oh (Zone 6a)
Forum moderator I was one of the first 300 contributors to the plant database! Cut Flowers Winter Sowing Charter ATP Member Seed Starter
Echinacea Plant and/or Seed Trader Region: Ohio Region: United States of America Butterflies Hummingbirder
Image
kqcrna
Feb 3, 2013 6:28 AM CST
I use several of these cheap heat strips. They work great for me.

http://www.wormsway.com/detail.aspx?t=prod&sku=FGP301

Karen
Surprisingly GREEN Pittsburgh (Zone 6a)
Rabbit Keeper Bee Lover Cat Lover Lover of wildlife (Black bear badge) Butterflies Hummingbirder
Dog Lover Birds Plant and/or Seed Trader Bulbs Echinacea Irises
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crittergarden
Feb 3, 2013 8:24 AM CST
Also, someone told me that I could use the "pipe wrap" under a towel.....
SHOW ME YOUR CRITTERS! I have a critter page over at Cubits. http://cubits.org/crittergarden/thread/view/73275/
Name: crystal lupton
north wilkesboro ,nc (Zone 7a)
Garden Art
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RainRabbit
Mar 22, 2013 4:30 AM CST
heat tape made for winterizing water pipes is what i use . you get it at lowe's or home depot . it is much cheaper than heat pads or heat tape made for greenhouses and works great . i put it on my tables in the greenhouse under a layer of sand .
~~~RainRabbit~~~
Name: Cheryl
Kingwood, Texas (Zone 9a)
Region: Texas Greenhouse Composter Plant Identifier Plant Lover: Loves 'em all! Amaryllis
Plumerias Ponds Foliage Fan Enjoys or suffers hot summers Tropicals Garden Ideas: Master Level
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ShadyGreenThumb
May 25, 2013 11:26 AM CST
I have starred everything on this thread! I need to get better at seed-starting. I suck at it. I think the heat mat will help! Thanks. Hurray! btw, check with metal/junk/appliance haulers. Many ovens are given away with their racks.
Life is short, Break the rules, Forgive quickly, Kiss slowly, Love Truly, Laugh
uncontrollably, And never regret anything that made you Smile.

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