Greenhouse Heat

I have just started some plants in my greenhouse and would like to know what heat temp I should keep it at. It is a small gh and I am very new at it. I am growing mostly vegtables and perenials.
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Chuckie Wrote:

Hi Chuckie,
I don't have your answer, but you might want to ask these folks. http://tinyurl.com/5axyn
New
-- Newt
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I have also had a new problem. I cannot keep a warm temp in the greenhouse. I would like to have a 70 degree day temp and 60 or 65 night temp. It is a small gh so there are no vents or windows. It is just 7 by 5 ft. Is there any insulation tatics I can use to up the heat without having a big electric bill? Chuckie
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Does "started some plants" mean planting seeds? In that case, you need some localized bottom heat to keep the germination medium around 75F. The entire greenhouse doesn't need to be maintained at 75F to start the seeds.
For the rest, (reading your follow-up post), the very design of greenhouses makes rapid heat transfer one of the facts of life, though some (clear) materials may retard it more than others. On a sunny day, the interior can easily be 20-30 degrees warmer than the outdoors. However, this heat dissipates quiickly when the sun goes down, and will soon reach something very close to the outdoor temperature.
You have 2 problems: with no vents, the inside heat will build up enough to cook plants once it's above 60F or so outdoors. And with no additional heat source at night, if it is below freezing, they will freeze.
I don't know of many common veg or perennials that require nightime temperatures of 65 degrees. You might more reasonably shoot for 55F. There are ways other than electricity to heat greenhouses -- search on "greenhouse heaters". But you *will* have to supply supplemental heat of some sort. Unless you live in zone 9+ -- you didn't mention your local conditions.
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I have only been able to keep a 50 or 55 night temp no matter what I do. I live in norteastern ohio and for the last couple of days there really has not been any sun to speak of. Today though the sun broke through and the gh heated up to high temps. I had to open the door to keep the heat down. I do not have any plants yet I am still waiting on them to sprout but it there a temp the gh should be at when plants are growing? Chuckie NE Ohio
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As I mentioned, many (most?) common veg and flower seeds need about 75F to germinate. This is why people often start seeds in trays on the refrigerator or water heater -- bottom heat warms the planting medium and the seeds sprout. Once they're up, they need light, and can take somewhat lower air temperatures. There are various versions of heating mats that will provide localized warmth. Take a look at
http://www.gardeners.com/Shopping/department.asp?DeptPGID 690&lstCategory=0&RecGroupNum=3
These can be quite pricey, but last a long time and use very little power. People have also devised 'home-brew' heaters with electric blankets and the like. Be careful -- electric blankets aren't designed to be operated when wet!
If you have a seed-starting tray with a clear cover and bottom heat, you have a mini-greenhouse that should protect the seeds even when the big temperature inside the big greenhouse gets quite low. Once the seeds sprout, and grow enough that you have to remove the cover on the seed-starting tray, the bottom heat will still provide a fair amount of localized warmth. It is suggested that things like tomatoes and peppers not be set outside until the nighttime temperature is above 55F, so I would say that keeping the greenhouse somewhere above that temperature for the growing plants would be sufficient.
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Thank You I would actually consider heating pads but I can't afford them right now. I have been sucessful keeping the house around 73 without any sun during the day. I planted these seeds 6 days ago when will I begin to see green shoots?
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Check the seed packets, if you have them, for *average* germination times. You can also find info on the web by searching for "plant_name germination" (without the quotes). Remember these times are averages, not certainties. Do NOT dig up seeds to see how they're doing. :-)
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wrote:

What do you recommend for the bottom heat? I have a home built greenhouse with heat and cooling but it would be nice to just have to heat the bottom until the plants get up.
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wrote:

designed fot the purpose. See
http://www.gardeners.com/Shopping/department.asp?DeptPGID 690&lstCategory=0&RecGroupNum=3
(The pricey mats with metal racks -- top row, 3rd pic from left -- were a little less then.) I also got a cheaper insulated wire that one buried in the growing medium of a sort of open tray. Rather like what must be insde an electric blanket, I think, but a reasonable length and designed to work in damp/wet material. It was a little hard to coil it around to give uniform coverage, but it worked.
I've heard of people using actual electric blankets. My concerns with that would be electrical hazard and possibly range of the heat. It doesn't take much to cook a plant in an enclosed space.
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I have heard farmers and gardeners using manure under the greenhouse to produce heat during the cold months. Apparantly, it works but you have to regulate the heat with amount of rotting manure and available sunshine. Electric heat would be costly if the greenhouse is large.
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Yeah they are called Hot houses. Many of them were put right outside a basement window. They would put about three inches of manure under it and grow their plants during the winter. Apparently it works from what I have heard. Chuckie zone 5
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