Greenhouse Heating Options
 

March seems to be the Winter that wont end. Im looking out the windows, and its snowing, again. For my area, this is highly irregular. Usually during March we get a cold snap that is about a week long, and its over. Not this year. Its really putting everybody to the test.


My poor little plants are suffering. Dont know for sure, but im guessing the combo of gray days and overnight cold is doing its damage. In about a week and a half I should start selling, and its not looking promising. Ill have some flats, but not a lot by any means. Which is really disheartening. On a side note, I was at my Wholesaler a couple days ago, and even some of their plants have some stress. So it can happen to anybody.


So, I have come to the point that to build my plant business, I have to seriously consider real heating options for when the weather gets like this. Im not looking to keep the GH's at 75 degrees, but warm enough that seedlings dont become damaged when the temp. bottoms out.


3 realistic options. Propane, Nat. Gas, and Wood. I left electric out, because that would cost a bloody fortune. Especially considering Duke Energy is wanting a 16% increase, to pay for a mess that they made and are being forced to clean up... But thats another topic for another day.


Natural Gas. I have natural gas already piped to my house. We have a gas furnace and a gas stove. Thats it. We have the bill set up to average out over the course of the year. Mainly because we were tired of paying the minimum in the summer for the stove, and then getting hit with a high bill in the winter. It just makes sense.


I could trench a line, about 150 feet, out to the seedling house, and install some sort of gas heaters. The additional cost would obviously just factor into the average bill. Im not sure there is a way to estimate how much that would add.


Propane. The people at Tractor Supply have kept me going. Or maybe I have been keeping their propane business going. The young lady at the register yesterday actually said "you sure do buy a lot of propane". Luckily they charge by the gallon. The current price is $2.69 a gallon. I have used all sorts of propane heaters. I prefer the blue flame over radiant.


Bulk propane is available. Last year when I checked, it was actually more expensive per gallon to have it delivered. Plus, a lot of complaints from folks who have home delivery. My understanding is to read the fine print, very carefully. I would probably be better off to purchase 100 pound tanks and haul them to TSC. I could strap them to a dolly and roll right up into my cargo trailer. It has a ramp to lower down. Would be much easier then lifting into the back of my truck.


Wood. I have an unused Wood Insert. I could drag it out there and start feeding it. Couple of draw backs to wood. Its a semi-permanent install that takes up a fair amount of space. And, you have to keep feeding it, all night long. I like sleeping myself. But on a positive, I currently have a metric ton of free firewood on my own property. That is a bonus.


Yesterday I went to Lowes and bought 2 more propane heaters. These were on clearance for $45. Had been $135. The reviews were mixed, but for the price its worth a shot. Plus if these do work out, they are duel fuel. Propane OR Nat. Gas.


[URL]https://www.lowes.com/pd/Thermablaster-10-000-BTU-Wall-Mount-Natural-Gas-or-Liquid-Propane-Vent-Free-Convection-Heater/999977962[/URL]


I mounted both on the West wall of the seedling house. Each has its own propane tank. They are spaced about 8 feet apart. Although a combined 20000 BTUs isnt that great, Its doing the job. The current temp. outdooors is 33 degrees. Inside the seedling house its 46 degrees. As I have typed this, its warmed 2 degrees. I do have a fan at the peak that is running very slowly, just to keep the air stirred a bit.


Are there any other realistic options that I have missed?

A crappy pic, but you can see how the heaters are mounted. This was quick and dirty yesterday afternoon, but it got the job done. I screwed scrap 2x3s to the upright supports. The heaters have keyhole mounts on the backside.


[img]https://i.imgur.com/iQVBungl.jpg[/img]

You propane system looks good to me, especially if you only need it for March. How are you venting it?

Heating a greenhouse is a difficult endeavor, to say the least.

At the moment, I am able to heat a 4' x 40' section of greenhouse bench with just a small electric space heater. The cost is maybe $1 per evening. I put hoops over the benches, cover those hoops with plastic each evening, and place the heater underneath. The middle bench is about a foot higher than the others. The heater is under it, and the warm air flows upward out each end, and then fills the plastic tunnel of benches. I'm getting about a 20-30 difference in temperature, which is huge in terms of greenhouse heat. To make the entire greenhouse that warm would take a colossal amount of energy.

I do have to make sure to get up in the morning and remove the plastic, especially on sunny days, so I don't cook everything. And this method does not work as well when my plants get bigger, because the leaves really hate touching the plastic, but it will get me through March, when I have my coldest spring weather. I will have plants to sell this Saturday, March 24th, at my first market of the spring.

I recommend using a online heating fuel comparison calculator or downloading the app Heating Fuel Comparison. Enter your cost for electric, propane, and natural gas and it will tell you what will be most economical for you. Most likely it will be natural gas.

Many people think electric is so expensive, but in our neck of the woods, it is much cheaper than propane.

The vent free heaters can be a concern, if the room is fairly tight, eventually you run out of oxygen. If they don't burn correctly, they will produce carbon monoxide.

[QUOTE=Salsacharley;690644]You propane system looks good to me, especially if you only need it for March. How are you venting it?[/QUOTE]

The heaters are vent free. Even if they werent, the GH is leaky enough that it doesnt really matter. This is an area that I could improve in as well. I need to get more wiggle wire and track, in order to seal down the edges of the plastic better.


In the long term, I plan to be utilizing at the seedling house all year, so heat needs to be available as needed. Some flowers take forever to grow, as well as keeping potential Mother Plants for cuttings. But that is later on, not a high priority this second.

[QUOTE=Cole_Robbie;690673]Heating a greenhouse is a difficult endeavor, to say the least.

At the moment, I am able to heat a 4' x 40' section of greenhouse bench with just a small electric space heater. The cost is maybe $1 per evening. I put hoops over the benches, cover those hoops with plastic each evening, and place the heater underneath. The middle bench is about a foot higher than the others. The heater is under it, and the warm air flows upward out each end, and then fills the plastic tunnel of benches. I'm getting about a 20-30 difference in temperature, which is huge in terms of greenhouse heat. To make the entire greenhouse that warm would take a colossal amount of energy.

I do have to make sure to get up in the morning and remove the plastic, especially on sunny days, so I don't cook everything. And this method does not work as well when my plants get bigger, because the leaves really hate touching the plastic, but it will get me through March, when I have my coldest spring weather. I will have plants to sell this Saturday, March 24th, at my first market of the spring.[/QUOTE]


Im sure you can appreciate the problem of running out of room. Because you will eventually. Especially with getting into Hanging Baskets, Potted Flowers, etc. There is only so much bench space.

[QUOTE=Rockandrollin;690721]I recommend using a online heating fuel comparison calculator or downloading the app Heating Fuel Comparison. Enter your cost for electric, propane, and natural gas and it will tell you what will be most economical for you. Most likely it will be natural gas.

Many people think electric is so expensive, but in our neck of the woods, it is much cheaper than propane.

The vent free heaters can be a concern, if the room is fairly tight, eventually you run out of oxygen. If they don't burn correctly, they will produce carbon monoxide.[/QUOTE]


You bring up some interesting points. Thanks for the advice on the app.

Cole Robbie's trick of heating below the bench / under cover is a really good one. I tried running a space heater in my greenhouse once and it was useless. Wasted energy and nothing got warm. If I had to try again, I would follow your example Cole. :yes:
Can't do that with propane though. The heaters look good FourOaks but I would be concerned about venting. Better safe than sorry! :?!?:

Well, its a good thing I have 2 heaters with 2 seperate tanks in the seedling house, cause 1 tank ran dry. :evil:


This cold needs to move on out of here. Next 2 days are supposed to be sunny, around 60 degrees. Then more gray days. :no:


Least the sun has been shining since sunrise. Its already 62 under the plastic.

I'm out of space now, and of course the weather has turned unseasonable cold, with lows right around freezing for several nights this week. I bought a diesel/kerosene salamander/job site heater last fall. I have problems with it shutting off, so I put it on a timer, and that helped a little. But I can tell from the fuel consumption that it is not running enough. So I just now built a fresh air intake for the heater, which is a blower connected to a wall so that it draws in fresh air. The idea of pulling in cold air into a structure I am trying to heat is counter intuitive, but if it keeps the heater running, then it will more than compensate for the cold air it draws in.

I am probably going to have to stay up and watch it. If the heater shuts off and the blower continues to run, that would be bad.

I am switching next year from electric to kerosene. Much cheaper in Georgia.

Back to the drawing board, the intake blower does not help at all. The heater still shuts off after about five minutes, and the little light on it blinks. It makes the greenhouse smoky on the inside. I don't know what else to do except place it outside.

From old school thinking and experience:

Cole, not that I know anything about greenhouses, but the kerosene salamander should work better outside blowing in. If it is anything like the ones we used in the 1980s and 90s - the thermostat kicks in by the temperature of air going into the unit - causing it to shut off when the intake air is warm enough. In theory, that works, but it can get too cold before the unit turns back on. Keeping it outside blowing in could also cause it to never shut off. You're going to need to do some math on using that timer.

Like I wrote in the beginning of my post - it comes from old school thinking and experience.

I've been using a kerosene heater this spring. It's about a 10000 BTU unit. I'm loving it. It's just right for my 10' X 12' little greenhouse. My greenhouse could benefit from a fan in the peak, and additional draft-sealing.

Battery-powered carbon monoxide alarms are inexpensive and readily available.

If you are using a fuel burning unit in a GH, particularly one that is not vented to the outside, it will be the [I]best[/I] $20 you ever spent. :yes:

We had a diesel powered Webasto heater in our box van, the darn thing was always breaking down.
Not good at 30 below.

Worth

[QUOTE=Cole_Robbie;693200]I'm out of space now, and of course the weather has turned unseasonable cold, with lows right around freezing for several nights this week. I bought a diesel/kerosene salamander/job site heater last fall. I have problems with it shutting off, so I put it on a timer, and that helped a little. But I can tell from the fuel consumption that it is not running enough. So I just now built a fresh air intake for the heater, which is a blower connected to a wall so that it draws in fresh air. The idea of pulling in cold air into a structure I am trying to heat is counter intuitive, but if it keeps the heater running, then it will more than compensate for the cold air it draws in.

I am probably going to have to stay up and watch it. If the heater shuts off and the blower continues to run, that would be bad.[/QUOTE]

Cole, before I bought the Thermablaster Heaters, I was going to buy a Propane Forced Air Heater, cousin to your Kerosene Heater. But naturally, by that point most retail locations were already sending back stock to make room for spring and summer goods. Thats why I had to get what I got, but at least I got a good price on them.


Meanwhile....


I know of a small nursery business that uses the forced air heaters in their tunnels. So, they definitely work. But I think moving the heater outdoors, with it blowing into some ductwork would give you better results. I know they say specifically to NOT do that, but whats the worse that can happen?


Or maybe, prop open a door, placing the heater right there, then some scrap plastic to help seal the opening?

[QUOTE=FourOaks;693486]
Or maybe, prop open a door, placing the heater right there, then some scrap plastic to help seal the opening?[/QUOTE]

That's what I did for last night. It ran fine when I tested it at about 11 pm. I hooked up the timer and left it. I will be able to tell from fuel consumption if it ran as programmed.


edit: oh I hooked up the timer, all right....and then didn't plug the cord into the timer, so the heater didn't run all night. Low was 32 for several hours, but clear sky. Almost all my stuff is now freeze-nipped, especially what I was going to take to market next week. Nothing is dead, but a lot of it is damaged enough to where no one will buy it, which is worse than being dead, continuing to take up time, money, space, and a lot of wasted effort.

In my area nothing can beat natural gas price wise, and I use a bunch of it. LOL Some days 2 million BTU's an hour. If you want to do it right, buy a natural gas heater, vent it, and use circulating fans to blow the air around your GH. Set your t stat on 62, and you should have some incredibly healthy happy starts. Just my two cents, this is how we do it in the far north, where it is very cold sometimes.

[QUOTE=AKmark;693536]In my area nothing can beat natural gas price wise, and I use a bunch of it. LOL Some days 2 million BTU's an hour. If you want to do it right, buy a natural gas heater, vent it, and use circulating fans to blow the air around your GH. Set your t stat on 62, and you should have some incredibly healthy happy starts. Just my two cents, this is how we do it in the far north, where it is very cold sometimes.[/QUOTE]

2 Million BTUs! I have a 2.5 ton natural gas furnace on my house blowing around 100,000 BTUS. I know how much that costs. I couldnt imagine 20 times that amount. Maybe they would give me a price break?:lol:


Seriously though, I do run a fan at the peak of the seedling house on a really low speed. My thoughts are that it should help to circulate the air a bit.

[QUOTE=Cole_Robbie;693504]That's what I did for last night. It ran fine when I tested it at about 11 pm. I hooked up the timer and left it. I will be able to tell from fuel consumption if it ran as programmed.


edit: oh I hooked up the timer, all right....and then didn't plug the cord into the timer, so the heater didn't run all night. Low was 32 for several hours, but clear sky. Almost all my stuff is now freeze-nipped, especially what I was going to take to market next week. Nothing is dead, but a lot of it is damaged enough to where no one will buy it, which is worse than being dead, continuing to take up time, money, space, and a lot of wasted effort.[/QUOTE]


Cole.. just saw your update. Dont fret, my stuff was looking absolutely horrible. Once the temps went back up, and we started getting sunshine, they have come out of it. Most stuff anyways. I have just a few flats that I will probably toss. Not bad out of roughly 200 or so.


On another note, I was surprised last week at my Market. I sold quite a few plants that had cold damage. I explained the damage, and the customers didnt mind at all. I was shocked.

I'm probably going to build a passive solar greenhouse. I can't see ever overcoming a huge heat bill in sales. I can get 50 gallon drums for free and can build the frame with 2x4s. Just something long and skinny I can fit about 50 flats in. That would get me through the early season.

FourOaks, I'm glad to read that most of your plants are looking better, and they are selling. I do wish I could have offered helpful info for you.

If I had a greenhouse here in this part of Texas - I would need heaters and an air conditioner. :lol:

[QUOTE=BigVanVader;693585]I'm probably going to build a passive solar greenhouse. I can't see ever overcoming a huge heat bill in sales. I can get 50 gallon drums for free and can build the frame with 2x4s. Just something long and skinny I can fit about 50 flats in. That would get me through the early season.[/QUOTE]

Just 50 flats? You know what they say about building a bigger greenhouse then what you think you need. :yes:


If you do this, please do post any and all results. Im really curious about the water barrel designs. I have researched them and understand the pros and cons. For instance, lack of Sunshine. Without it, they dont heat up. For us, the month of March was absolutely horrible. I have never seen so many gray overcast days. We would have 1 sunny day a week. It was that bad.


As far as overcoming the cost of heat. I think the strategy is to cram as much as possible in the GH, to maximize the profit. I need to go over my receipts and see where I stand on propane purchases.

[QUOTE=AlittleSalt;693589]FourOaks, I'm glad to read that most of your plants are looking better, and they are selling. I do wish I could have offered helpful info for you.

If I had a greenhouse here in this part of Texas - I would need heaters and an air conditioner. :lol:[/QUOTE]

Oh believe me, they get hot here too. The other day the seedling house got upto 115 degrees. I finally decided to roll up the plastic. :lol:

While Im thinking about it, some observations.


I probably should write this down somewhere, but I took note of some cold damage hardiness. Some stuff just took it better then others. Which is really no surprise. Most of the damage was brown crispy leaves. Most plants went into a state of dormancy. Now the weather is getting better, most plants have new growth and are turning nice and green.


Tomatoes - Most varieties showed signs, and slowed down in growth. To the point of looking dormant. Interestingly the variety "Aunt Rubys German Green" never showed any signs of damage. Just slowed down. Maybe it has cold hardiness?? The worst was "Large Red Cherry". Most have never recovered.


Peppers - Very similar to the Tomatoes, and are finally starting to come out it. The worst was Jalapenos. The best, Cal-wonder. edit: Actually the worst is a toss up between Poblano and Anaheim. They might just be trashed. Maybe not. Kinda curious what the end result will be.


Eggplant - Only started "Stars and Stripes". Will probably be trashed.


Artichokes - Imperial Star is the only variety, and they cruised thru the cold like it was nothing. These also sold at the Farmers Market like Hotcakes. Next year, Im going to start a lot more. Thats for sure.


Herbs - Sage, Oregano, Parsley, Thyme all slowed down. The Oregano and Sage showed some crispy leaves, thats about it. Basil slowed but the true leaves never showed signs. Which surprises me, based on everything I read about Basil hating the cold.


Lettuces and Cabbages no damage.


Snap Peas in the raised beds took forever to sprout. But they are growing now. My main concern is that it will get hot before they produce. So now I have a race on my hands.


Sunflowers - No damage whatsoever. Just slowed down.


Stock - No damage.


Dahlias - Only lost 1 or 2 plants out of 5 flats? Think that was due to critter damage. Otherwise, no signs of cold damage.


Marigolds - Strawberry Blonde showed the most damage. They are very slowly coming out of it. Petite Mix, and French Vanilla showed some signs but nothing like SB. Eskimo just slowed a little bit. No noticeable damage.


Sweet Pea - no damage.


Cosmos - no notable damage. Just slowed way down.


Zinnias - Surprisingly no damage. Just slowed down. Maybe lost 1-2 plants to unknown causes.


Thats all off the top of my head. Other stuff like Cucumbers and Various Squashes never got exposed to the extremes in March, so they are growing just fine.

It is plenty sunny here to use a passive solar design. I would likely add a heated/circulating system for backup (like AKMarks wood stove/water system) though to warm the water when/if needed. Another positive is that they regulate heat very well so useful here even in the dead of summer. A reg greenhouse would be useless here in the summer temps, Id have to open the ends to keep it cool enough.

50 flats is a lot for me to do by myself b/c I work full-time + 3 kids. I like to have a balanced workload so I still enjoy growing and have a little free time. Plus many times people get into the more money for more stuff hamster wheel and never get off. I do want to do this full time at some point, but I think growing slowly as my customer base does w/o ever going in debt for anything is the way I'm comfortable doing it. Otherwise I feel like I'm being self-centered about my hobby. This Spring has been a wild fun ride though! Hoping all these freaking flowers sell by Mothers Day!

As long as you have a backup plan, then go for it.


I think the next 2 tunnels that I plan to build will have plastic that either rolls all the way up to the top, or sections that are entirely removable.


The heat is a killer, thats for sure.

My plan for tonight, since it is going to rain and snow, and I need to cover my heater, is to put the topper shell off my truck over it, supported by a block under each corner so that enough air can get to the heater. I feel like redneck MacGuyver.

[IMG]https://img.memecdn.com/MacGyver_o_49416.jpg[/IMG]

[QUOTE=Cole_Robbie;693715]My plan for tonight, since it is going to rain and snow, and I need to cover my heater, is to put the topper shell off my truck over it, supported by a block under each corner so that enough air can get to the heater. I feel like redneck MacGuyver.
[/QUOTE]

What? No Duck Tape?:lol:

Apparently, I should have run the heater all night constantly and not used the timer. Almost everything has freeze-damage now, especially my tomato plants. I will be culling and giving away a lot of plants next week. They will all live just fine, but no one will buy them with burnt-off edges. The plant selling season has been a complete bust so far. I'm not even sure when I will be back at market.

I'm also coming to despise that diesel heater, especially the smell. Just being in the greenhouse after it has run makes my clothes and hair stink. The smell seems to follow me around. I may have to experiment with kerosene to see if it stinks less.

Is propane out of the question?


Im trying to hash together a plan for this winter into next spring. I have a Wood Burner, but hate the idea of constant feeding. I have plenty of accesible firewood.. that helps to ease some pain.


Or maybe, something like a pellet burner? They have an auger, and burn plenty clean.