Heating mat question

Check out THIS heating mat....

http://allthingsplants.com/thread/view/7543/How-ingenious/

Gymgirl - thanks for the link - I have never heard of an electric roaster. I had thought of Horseshoe's idea of using the oven, but then thought of the mess I'd have to clean up if I spilled "dirt" in it!

A roaster would be PERFECT! Almost like an incubator.

Brilliant idea! Now I just have to find a roaster! LOL Leave it to Patricia to come up with a wonderful idea.

BTW, I saw several roasters at the goodwill for sale for cheap when I dropped off donations the other day.

If you do many flats you would need lots of roasters!

Stagger the germination.

You could probably rig a way to stack them in the roaster, too.

I have never really understood the need for heat mats... maybe because I have my seedlings starting in a spare room which is the same temp as the rest of the house... roughly 70F. But I find that my shop lights give off quite a bit of heat for the shelf above it. Works good enough for me, so I simply can't justify spending so much money on mats. I start my plants from seeds for two reasons... first, as a hobby, and second, to save money on buying plants in spring.

I hear yah, Lorvan. Same here!

And, with the Roots Organic potting soil I just started some seeds in (as an experiment compared to seeds started in Sunshine Plug and Seed Starter mix, with no amendments), unless you live in the North Pole, you should NEVER need a heating mat!

I never saw seedlings take off so fast and turn out so healthy! The stuff is $$$ for a lot of us at-home gardeners (me included), but, it's worth a shot to buy one small bag and see what it does. You can decide from there to continue or not.

In my case, I'm going to work on purchasing the amendments individually, and mix up my own stuff. I think I could come out a lot cheaper and get close to the same soil make-up.

Linda

Doggobnit- I gotta go find some Roots Organic! Just can't stand hearing all the good about it and not having any!!!

>> unless you live in the North Pole, you should NEVER need a heating mat!

I keep my house around 56 F when I'm not home or asleep (almost all day 5 days per week), and 60 F when I am home and awake, uless I have guests.

A lot of seeds germinate faster and more consistently at 70-75 than at 55-60.

I luv my heating mat

Me too- heating mats do get the seeds motivated to pop---

Yep. Peppers & eggplant, cukes and squash (started in peat pots, nice if you're up north with a short season or just impatient ;o). Just to name a few more common ones. There are a lot of tropical plants that need more heat to germinate, and if you want blooms or fruit the first year that's a good way to do it. Heat mats only require the space they take (they come in a variety of sizes), an electric outlet and maybe a grow light. It sure beats building an entire hot bed or cold frame if you don't need that much. And if taken care of (not left bent or under piles of heavy boxes, or stepped on) they should last a long time.

I'm really appreciating mine right now. I've got peppers and eggplant started that would be rotting in my garage otherwise (just hear they've dropped the overnight forecast again - to 23ºF! Sure wish that global warming would get here! [vbg]

-Rich

Update to my January 29th Post #8986409

I have been delighted with the heat mat and thermostat. I've been using them in conjunction with a Jiffy greenhouse I purchased at W-mart. It has the same dimentions as the heat mat.

I did not use the pellets that came with the greenhouse as I prefer my own soil recipe. The 3oz plastic Solo cups I use for germinating seeds fit perfectly under the greenhouse's dome. I had to cut a small up-side-down "V" in the side of the dome to accommodate the heat map's probe.

Today, I purchased three more Jiffy greenhouses.

Two questions: Is there a way I can join more heat mats to the thermostat? Or do I have to purchase a thermostat for each heat mat.

Honeybee,
Maybe you could use a 6 prong power strip, plug the mats into that, the strip into the thermostat, and the thermostat into an outlet. Or a multi pronged extension cord, depending on how many mats you have. Someone else who knows more about electricity than I do would have to tell us if this could overload the system! The only problem I see with it is that each mat might be at a different temp so that it would be hard to regulate more than one at a time! Just thinking out loud. I love to solve problems even if I don't know what I am talking about but I would probably have tried this route first. I also have two mats so would like an answer to your question that is safe and works!

gardadore - thanks for your answer. I, too, wondered whether plugging more than one mat into the thermostat would overload it in some way.

Guess we'll both be waiting for someone more knowledgeable to give us an answer. ^_^

Honeybee,

You may want to consider a thermostat per heat mat. The problem with tying together is that the mats may heat differently, or the soil characteristics in each tray may differ (moisture, air, etc.) One tray, with the sensor, might be fine, but the other mats, that were heating trays without sensors could vary in temperature --to hot and the seeds are cooked, too cool and they germinate slowly or not at all.

David

David,

I think you are right. That is something I also wondered about above (besides possibly burning the house down!), that each mat would have different trays on it with various needs. Actually I find that I don't need a thermostat at all. I monitor the trays several times a day and when something sprouts it immediately goes under the lights so the plants don't get too tall and leggy. I also shade the trays with cardboard bent on its sides so that the sun doesn't hit the trays directly (They are on the floor in front of a picture window) which could heat things up too much, especially since the trays have plastic covers on them to keep the moisture in.

When my heat mat is giving too much heat to the seedling tray, I place the mat directly on a piece of ceramic tile. That way the heat is disbursed down to the tile and away from the seedling tray. If I want more heat to the seedling tray, I will use a standard dining place mat, which happens to be the perfect size, to insulate between the piece of tile and the seedling tray. This sends more heat up to the tray and away from the tile. Not very high tech but it does work.

I just use a couple small pieces of wood to elevate the seedling trays so they are not sitting directly on the mat. Worked great so far this year.

David, I think you are correct in thinking each tray should have it's own thermostat. Guess I'll have to re-write the gardening budget (again) for next season LOL

gardadore, Mary, and postmandug

I have the heat mat on a wooden shelf. So far this has worked out very well.

There has certainly been a difference in the number of successful seeds sprouting, and the time between sowing and sprouting has increased exponentially.

Heat mats are very low-current low-power devices. A 4-tray mat pulls about as much as one 48" flourescent bulb,
so one 2-tube shop light pulls about as much power as enough heat mats for 8 trays.

I see a one-tray heat mat rated at 17 watts, and a 20"x20" (4-tray) mat rated at 45 watts.

I don't think many of us could afford to buy to buy enough heating mats to overload a circuit breaker, size-outpet strip or a thermostat. I saw one thermostat rated at 1,000 Watts maximum, which woiuld be 140 of the single-tray mats or 22 of the 4-tray mats.

A 20-amp circuit breaker ought to be around 2,400 Watts (so there seems to be plenty of safety margin inless you have 2,000 Watts of light bulbs ... which would be 37 to 62 48" flourescent tubes.

I think a 48" T5 one-tube flourescent tube pulls around 54 W
and a 48" T8 tube pulls 32 W.
Standard old-fashioned T12 48" tubes pull 40 Watts (but give less light).
(There are probably other models with somewhat different ratings).


But if my numbers are right, you could run all these together on one curcuit:
- 8 48" T5 2-tube flourescent fixtures PLUS
- 8 48" T8 2-tube flourescent fixtures PLUS
- 8 20"x20" 4-tray heat mats
...
for a total of only 1,480 W ...
and one 20-Amp curcuit breaker could handle it all with 920 W to spare.

Do flourescent fixtures have startup inrush currents of double their rating?
Maybe check with an electrician if you have more than 12-16 shop lights all starting up simultaneously.

Those are good guesstimates, Rick/Corey. I'd feel perfectly comfortable going with that.

"David, I think you are correct in thinking each tray should have it's own thermostat. Guess I'll have to re-write the gardening budget (again) for next season"

Honeybee, you won't need a separate thermostat for each mat. I run 25 feet of heat mats off ONE (edited cus I wrote "off" twice instead of "one-sorry) thermostat and have done so for quite a few years now.

What IS important though is to keep in mind your pot size, or tray size, and the soil medium. (I think someone above may have touched on this.) Since you would normally be using the same seed starting soil/medium you should have no problem with the medium differences. What would come into play would be having your thermostat probe in a 4" in pot (for example) but then have your seed trays in various/different sizes (row trays, quart pots, gallon pots, etc). If your probe in the 4" pot is telling the thermostat to cut on or off according to the temp of that pot then your other pots, be they larger or smaller, will either never be heated enough or could be heated more than necessary. So...

...basically, keep your seed starting containers the same size as the container the probe is in and you will be good to go.

Hope this helps.
Shoe

This message was edited Mar 31, 2012 12:22 PM

Thanks, Shoe, that was very helpful and should solve the problem for a number of us!!

Jessica

You're welcome. I couldn't do w/out my heat mats, starting thousands of seeds on them as well as keeping the seedlings at a much warmer temp than they would normally be due to my refusal to heat my whole greenhouse. It is much easier (and cheaper) to heat the soil than to heat the air space in a big room or greenhouse.

Shoe

Shoe-Hi- haven't heard from you in awhile- now I see why!!You been growing! That's a nifty setup- I'm doing the same thing on a much smaller scale- I keep clear plastic tents around my trays that are on the heat mat.

Howdy, Jo...

Your tents are a great idea and will help keep your heat mat electricity down, too by holding in the heat longer. And I know you well enough that you are venting them so the moisture build-up isn't excessive.

Yes, very busy here so can only post when entirely exhausted or fizzled out! *grin. This morning I splurged and had extra coffee (Luzianne!) so used that excuse to read some DG!

Shoe

Yes, I pull the plastic back and open the greenhouse up during the sunny days. I have both heat & fans when needed.My little tomatoes are looking good. Funny, though- the best looking ones right now are from a delicious Roma tomato from Albertson's! I am aware that it may not come out a desirable tomato, but I like to experiment.

Rich, as I understand it, global warming just makes weather more extreme, not necessarily hotter everywhere.

Horseshoe -

That's very reasuring.

How do you hook them up to each other? (I'm not very electrically minded - LOL)

Shoe,

I loved the "shrink-wrapped shelving unit" inside a hoop greenhouse.

Do you have any clear plastic domes
over the trays,
inside the shrink-wrap
under the hoop tunnel
that Jack built?

I read about someone who grew lettuce all winter in Maine. He had at least three layers of heat protection. I think it was:
1. floating row covers
2. a low hoop tunnel, like 6" to knee-high
3. a walk-in big tunnel.

I like to think that he started his seeds under cloches under the row cover under the low tunnel under the hoop-house!

Since I worried even more about humidity in the past than I do now, I took off my "humidity domes" ASAP. But I kept a sheet of drywall (sheet rock) UNDER the heat mat, so al;l the heat went up and none went down.

Now I think that my sheetrock Bottom should have had Sides, so that it became a Hot Box.

Honebee...

Your thermostat has a plug-in (outlet) where you plug in your heat mat. That is where you would plug in a power strip. (Those are what give you more than one plug-in, perhaps like you have for your tv, dvd player, am/fm stereo, etc.) Then you plug in your heat mats to the power strip. Your thermostat will cut on and off according to the temperature sensor you've stuck in a selected pot/tray/whatever. Each mats temp will be governed by the pot/tray/whatever that your sensor probe is in, which is why it is important to have them close to the same size, same soil medium, etc.

RickCorey...

When I have a few trays on the heat mats, especially peppers or egg plant seeds, I put the plastic domes on them to help hold in moisture and heat. Once they germinate I take them off so there is no excessive build-up of moisture and they get proper air/gas exchange.

The "heat cabinets" (as I call them) do double duty sometimes and during those times I'll put umpteen trays of other seedling in them by cross-stacking them. The plants/seeds that need the direct heat are on the mats themselves; the germinated trays that need heat but not as much go on top of the others. IN order to do this I'll put another tray, as a lid, over the bottom trays (on the mat). Those trays hold in the heat for the still-germinating seeds and also give support to the trays on top of them. Once the plastic is pulled down for the night all is comfy and cozy.

Hope this helps.
Shoe

Shoe - thanks for the info. I have a couple of spare power strips, so I'll use one as you directed:

I plug each heat mat into a power strip.
Plug the power strip into the thermostat
Plug the thermostat into the wall outlet
Poke the temperature sensor into one of the pots

Did I get that right?

The cups and soil I use are all the same, plus I'll be sowing seeds that require pretty much the same temperatures as each other.

You got that perfect, Honeybee. Exactly correct.

And yes, having all the trays the same size helps for even germination. As time goes on you might want to get double-duty from your mats by cross-stacking some trays with seedlings that will benefit from the upward rising heat but yet not be the same (80º) temp as what is on the mat.

Shoe (off to check my g-house plants)

>> I'll put umpteen trays of other seedling in them by cross-stacking them. The plants/seeds that need the direct heat are on the mats themselves; the germinated trays that need heat but not as much go on top of the others. IN order to do this I'll put another tray, as a lid, over the bottom trays (on the mat). Those trays hold in the heat for the still-germinating seeds and also give support to the trays on top of them. Once the plastic is pulled down for the night all is comfy and cozy.

That's a new one on me! Stacking trays inside a heat box. Great idea. After all, heat isn't "used up" by passing through one tray. It's only lost if there is an air leak out of the enclosure, or by conduction through the plastic.

Shoe, and Rick,

Thanks for the great ideas which are practical and will save energy.

"That's a new one on me! Stacking trays inside a heat box."

Yeh, it just kinda evolved out of necessity, Corey. I think I'm going on more than a decade using that "system". I admit it is time consuming morning and evening because unload those heat cabinets and put all the seedlings on the g-house tables so they get their daily sunlight, then move them back, restacking them in the evening so they get their required heat. Boy did I used to grumble alot but nowadays it is just a given, needs to be done.

Honeybee, your heat mat will open up a whole new world for you. Enjoy it!

Shoe

Shoe -

It has and I am ^_^

Wish I had the mat during the spring of 2011 when it was so cold! I had a terrible time getting anything to sprout.

I'm already planning to purchase three more mats to go with the one I have, and use them with your idea of plugging them all into to the one timer.

The shelving unit I use to sprout seeds has room for at least three more 4ft shop lights. Hopefully I'll have some cash to buy those too next year.