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Kerosene heater for the greenhouse

What an odd thought, what image comes to mind: the world of kerosene… And now I’m in it! Purchased new today, at a healthy 35% discount, this small, rather inexpensive, KeroWorld-brand indoor kerosene heater is the core technology in the extended-spring greenhouse plan. The idea is to turn the unheated hoophouse into a barely heated one, by warming it at night so that it stays above 38°F (4°C). That way, I can put out seedlings weeks early, instead of crowding them under scarce indoor lighting until it warms up in April. It should also give the earlier-than-ever lettuce, going into the ground in the greenhouse, a smoother start. This heater is low-powered—10,000 BTU, recommended for 420 sq ft, it’s 640 sq ft out there—but only a wee bit of heat is required. I think. Last year’s propane space heater was quite efficient, but burned too much gas for every-night use, it often went out by itself, and it required lots of ventilation. Plus, I don’t really like relying on pressurized tanks. This heater will hopefully burn low and steady, and it’s pour-to-fill! Aided by a fan to keep the air moving, and row cover on the coldest nights, it should get the job done. This all reminds me of Patrick of Bifurcated Carrots’ comment a while ago about the line between good and bad technology. It seems a personal decision as much as anything. Why don’t I dream about full-blown winter greenhouses, with high-intensity lighting and industrial-strength heating and ventilation, I wonder? Dunno. I just don’t. But an extra growing month in the strengthening sun, and a little less reliance on indoor lights, traded off against some kerosene, well, THAT would be cool!

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20 Comments

  1. It looks like you made one hell of a nice investment. I lived on a farm for a few years when I was in high school; and the guy who owned the place heated his greenhouse with a little wood burning stove. I’m sure your greens are going to love it.

  2. I have a bunch of perennials, a few annuals, tomatoes, and peppers started at this point. I read that my greenhouse would have to keep a minimum temp. of 45 degrees at night before I could move everything from the house to the greenhouse. You mentioned 38 was the magic number. Is that true? I would love to move everything out there, I am way out of room inside, and would love to start my lettuces and brassicas.

  3. Reading of your decisions regarding heating the greenhouse, I thought you might find this interesting/educational.

  4. Hi Mike,

    That’s basically what I have here (I only have 2 buttons on the front, so you must have a deluxe model :-D ) and it’s what I was relying on to heat my house for 4 weeks when my central heating boiler broke down.

    What I’ve found is that you must remove the fuel tank when you switch it off. Otherwise the heat still at the burner end evaporates the kerosene and will basically empty the tank for you and fill the place with fumes.

    It does produce a lot of heat so be careful where you place it and it needs to be out of any drafts too as they risk blowing flammable things at it and also increases the amount of fuel burnt.

  5. Kelly: Yeah, I’m betting on a little heat going a long way. More Eliot Coleman influence!

    Christine: 38°F is my own magic number. I picked it as the very lowest “safe” minimum temperature to aim for when trying to keep heating costs down! I’ve heard the 45°F figure, as a safe nighttime holding temp (and 55°F as a min overnight temp for growing). I think they’re both very general and conservative. You really have to consider what you’re growing and the results want, and usually, it seems you can go quite a bit lower. In this case, I want to start one wave of seedlings on my grow racks, then move them out to hold for field transplant, making way to start another set on the racks. Seedlings are really tough in general, and if cold nights in the plugs slow them a bit, I’d rather that than growing too fast. In this case, it’s hardier seedlings (lettuce, brassicas, onions, parsley,…) that’ll be out there first, and they could probably stand 32°F air temp or even lower, no problem, especially with double protection of the hoophouse and row cover (row cover used in an unheated greenhouse can alone provide amazing results in the cold). Based on that, 38 sounds very safe. Experimenting is the thing, carefully break some “rules” and see what happens. You’ll probably be happily surprised!

    Annie: Thanks for the link! That was a good article, the kind of set-up that really makes me want to get to year-round growing more quickly. Passive solar is definitely possible, but can be so expensive. Search for “soap bubble greenhouse” (here’s a great action video!), that’s another approach I thought was gonna work out here a couple years ago, but the soap bubble generator ended up costing a fortune. This article said their costs were $18,000 for an 18×24 greenhouse. Double-walled polycarbonate greenhouses are at least 5 times the cost of a double plastic hoophouse like I have ($30/sq ft vs $5/sq ft) and that’s just the greenhouse, not the other solar stuff. So, like solar panels, it can be done, but it’s still mad expensive!! I hope I can budget in a small experimental set-up soon, at least.

    Deborah: Thanks for the tank tip! Like everything else, applying this simple kerosene heater to this particular purpose will have it’s own little learning curve…

  6. Terry

    I was searching the web using the subject ‘kerosene heater in greenhouse’ as my search subject- and you came up. This is my first time at your site here, but I don’t think it will be my last. It seems we have a lot in common- but you are a bit more advanced in experience than I am at this point.
    I was interested to read the comments. Yours wasn’t the first info that I read, but it was the most ‘personal’. I read several articles and most said in essence- “Kerosene? Forget it”.
    I bought a used greenhouse (affordable for me) and when I priced the cost of instalation of the 100gal propane tank and fuel that the previous owners had used when they had the greenhouse up and running, I decided to explore other fuels. This is my first spring with the greenhouse, and I am TOTALLY new at this! Reading your blog has been helpful. I have just enough room in the house under some lights to hold the seedlings for now.. But if I could just get the greenhouse up and running sooner, I could really get efficient use of this greenhouse. I liked your idea of using floating row covers in the greenhouse on cold nights, too. It seems that you have experience working in a cooler greenhouse., Do you have any advice for me? Is there somewhere I can go read about this? Thanks in advance, I really do like your website.! By the way, as I was exploring- I realise that you are talking about the Southern Tier! I am here, also! I can throw a stone at the Pennsylvania/NY border, and live about 20 min south of Elmira, NY. So, how-do, neighbor! Terry

  7. Terry: Thanks for the in-depth comment… I found it interesting how you noted that it’s the most “personal” of the sites you’ve been looking at for info. I’ve been thinking about that lately. I realize from comments and email that some readers are taking what I’m doing as advice, which is fine, but in the end, I’m mainly keeping a journal of what I’M doing, which isn’t always necessarily “right”! I try to point this out here and there, like, “this is an experiment” or “we’ll see what happens”. On the other hand, it’s kinda silly and tedious to always qualify everything, so I’m going to go ahead and just keep writing about what I’m doing and how it turns out… :)

    Re the kerosene, I didn’t do any specific greenhouse research on kerosene vs anything else, because I’m not going for any sort of traditional greenhouse heating, this minimal heating is a whole other thing. Kerosene is more expensive than propane, but you need a proper propane heating set-up (which it sounds like you may have). I used a propane space heater last year, it puts out more BTUs for the dollar, but it wasn’t too reliable or safe to leave it running unattended all night. I also have a couple of different small (1500W) electric heaters that I can run out there as well. But kerosene seemed worth trying as well, and I can also use it indoors in the seedling room if power goes out earlier in winter. So it’s a mix of economies and experiments.

    For minimal heating in the relatively small (640 sq ft) seedling greenhouse, I only need a very small amount of steady heat, plus air circulation, plus row cover. It’s a trial and error thing…

    You should check out Eliot Coleman’s books for cold-weather stuff. He’s done a lot of unheated and minimal heating work, and in the cold winters of Maine. His books, The New Organic Grower and Four Season Harvest are both well worth having, for hoophouse/cold weather stuff and for general market gardening. He also has a self-published book, Winter Harvest Manual, that you can order direct, and also well-worth it.

    Hope that’s useful…

  8. Terry

    Thanks for your great reply!
    I was actually thinking about getting the book “Four Season Greenhouse” Now I know I’ll be going to Amazon.com before I sign off the computer today.
    I am aware that you are reporting your experiences, and not offering ‘advice’ per se. But I have always learned best by reading the ‘experts’ and then asking for practical advice from people who are actually using the methods I have read about. I find that the experts don’t know everything! And people who are actually ‘doing’ whatever- have usually tweaked the method to make it better.
    Kerosene might be more expensive per gallon, but the initial cost of setup for the propane has been quoted at more than $460.00! I realize that this would be a one-time expenditure, but I just don’t have the cash right now. My husband and I discussed our options in-depth and perhaps if I sell off my extra plants and veggies this season, we can do the propane in the fall. By then, the price of gas will probably be even higher, but you can only do what you can do, Right?
    A kerosene heater would be useful in other applications, so it wouldn’t be a waste to get one. We heat with an air-tight wood stove with natural gas driven radiators as back up. So our old farmhouse (1853) is always toasty. But we have a workshop in an outbuilding that has no heat and in the dead of winter it is just too darn cold to work out there! A kerosene heater could be used out there.
    I was just curious about fumes/plants. I also have several small electric heaters that would be useful-IF-I had the ability to get electricity out to the greenhouse. But the greenhouse is situated a little more than 200 ft away from the nearest power source, and that is just too far for extention cords to make me feel safe.
    SOOOOO, I guess I will keep reading and learning this year to be ready for next year. As I said before, you can only do what you can do…Happy St, Pat’s!

  9. I’ve been unlucky enough to be an avid gardener in many cold places in Canada, so I’m always looking for more ways to (cheaply!) make it bearable for my plants. I have a woodframe greenhouse that’s 18’x45′ that I grow all my veggie starts in, even when it’s really cold. I scrounge as many water holding devices that I can – surge tanks, hot water heaters, barrels…you get the picture. As soon as it’s thawed out in there, sometimes I help that along with burning mill ends in the airtight heater for a week or so, I fill all the tanks and then they don’t seem to re-freeze. Apparently, water is the top heat sink material over anything else! Seems to work for me. Of course, I do what Mike does and start all the tough cookies first, the brassicas, lettuce etc.

  10. […] adding up, until there’s not enough LIGHT to go around. Into the equation, there’s the barely heated seedling greenhouse and the WEATHER: as soon as it’s reasonably warm enough at night, I can […]

  11. EtienneG

    Heating greenhouse with combustible is also something I am looking into, and like Terry above, I was wondering about the effect of fume and exhaust from the heating system, particularly when burning fossil fuel.  I plan on investigating alcohol burner (aka ethanol) as I understand it release only CO2 (which actually happen to be beneficial for plants!), although I doubt it will be competitive in term of cost.

  12. We have an overstock of 10,600 BTU kerosene heaters that we bought for the community during the recent ice storm. We have over 1000 in stock and   are selling below cost at $68. Price is negotiable based on quantity.
    Thank you for your interest, call me direct 812-542-2960.

  13. Kerosene indoor heater for the greenhouse Tiny Farm Blog | Portable Greenhouse

    […] Kerosene indoor heater for the greenhouse Tiny Farm Blog Posted by root 17 minutes ago (http://tinyfarmblog.com) This heater is low powered 10000 btu recommended for 420 sq ft terry thanks for the in depth comment i found it interesting how you noted that it the re the kerosene i didn 39 t do any specific greenhouse research on i 39 ve been unlucky enough to be an a Discuss  |  Bury |  News | Kerosene indoor heater for the greenhouse Tiny Farm Blog […]

  14. PENNY

    I got my double wall polycarbonate green house this spring and I am having such a great time trying to grow things that I would like to grow all winter as well so I am looking for  propane heater that still produces heat if the we lose power. We have a large torpedo propane tank  close to our green house and the propane is used only for generator back up for our house. I can get a company here to install the propane heater in my green house but I can not find where I can buy the heater. does anyone have any idea where I can but this sort of heater?
    This is the best site I have found and reading every one’s comments is very interesting,
    thanks,
    Penny

  15. Penny: Try a Google (or other search engine) search for “propane greenhouse heater”—there seem to be a lot of sites to check out!

  16. Kerosene heaters Opinion

    Which one better for the safety factor, using gas or propane as source power for heating or electric models? Hmmm… I prefer to use electric in spite of the cost is just little bit higher than others.
    But for a moment I also prefer to use kerosene heater, because I don’t no! Maybe it looks more unique or else ha4x!….
     
    Thank you
     

  17. Badbird

    We live in coastal SC and are using our vinyl (removable/sliding)widowed porch as a winter greenhouse.
    Typically, we don’t get too many really cold days (by Yankee standards), but are are trying to “winter over” our tropical plants (Hibiscus, Mandeville, etc.
    In the past we simply used a small electric heater with success, but we are now looking at either a small kerosene or propane heater.
    Our porch is about 25×30 with 3 exposed vinyl sides.
    We are comcerned about any fumes that may be the by product of combustion.
    Should we just bite the $$$$ bullet and stay with electric, or consider switching to kerosene or propane? We want something that can be safely left running all night.
    I currently use a tank mounted propane heater for working in the garage, but don’t leave it running all night – just when I’m out there.

  18. Exciting post. I have been searching for some good resources for solar panels and discovered your blog. Going to bookmark this one!

  19. Greetings from Carolina! I’m bored to tears at work so I decided to browse your blog on my iphone during lunch break.
    I love the info you present here and can’t wait to take a look when I get home.
    I’m amazed at how quick your blog loaded on my phone ..

    I’m not even using WIFI, just 3G .. Anyhow, fantastic site!

  20. Alan Gorkin

    hi- did you have any damage to your plants from the fumes, i thought you need a source of fresh air?

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