If you need more space for growing plants in the winter, a\ngreenhouse seems like a logical choice. However,\nthere is still the problem of germinating seeds and keeping plants alive in the\nwinter cold.\n\n\n\nSo, how do you heat a greenhouse? An\nelectric heater or warming mat will heat a greenhouse with electricity. You can also use a gas heater or wood stove\nto heat a greenhouse without electricity. \nUsing water barrels, stones, and insulation can all help to retain heat\nin your greenhouse.\n\n\n\nLet\u2019s take a closer look at how these greenhouse heating\nmethods work, and which ones might be the best option for you.\n\n\n\nHow To Heat A Greenhouse\n\n\n\nThere are many options for heating a greenhouse in the\nwinter. We\u2019ll start off with methods\nthat use electricity, but if your greenhouse is \u201coff the grid\u201d, then skip to\nthe next section.\n\n\n\nUse An Electric Heater To Heat Your Greenhouse\n\n\n\nYou can buy all sorts of electric heaters on Home Depot,\nLowe\u2019s, Walmart, or Amazon websites. However,\nthe heating capacity and prices will both vary considerably.\n\n\n\nThere are lots of ways to heat your greenhouse, some of which require electricity.\n\n\n\nFor instance, you can find portable electric heaters that\nare suitable for residential use for as little as $25. However, these heaters are only meant to \u201ctake\nthe chill off\u201d by warming a bedroom by a few degrees.\n\n\n\nThese small heaters are not really built for constant use to\nkeep a greenhouse at 60 or 70 degrees Fahrenheit when the outside air is\nfreezing.\n\n\n\nYou would be better served with a heater that is\nspecifically built for heating a greenhouse in the winter. This will require a heater with higher output\n(higher BTUH).\n\n\n\nThe higher the BTUH (British Thermal Units per Hour), the\nmore heat energy a heater can put out, allowing it to heat a larger or colder space.\n\n\n\nFor comparison, let\u2019s compare two heaters from\ngreenhousemegastore.com.\n\n\n\nA portable electric heater goes for $65 and has a BTUH rating of 5120\/4436 (input\/output).\n\n\n\nOn the other hand, a Modine H60 heater goes for $732 and has a BTUH rating of 60,000\/48,000 (input\/output). It weighs 80 pounds.\n\n\n\nThis translates to about 12 times the cost, for about 12\ntimes the heating capacity (that is, you get what you pay for).\n\n\n\nNote that the Modine heating units and others like it\nrequire a vent pipe. They should be installed by a certified HVAC technician,\nwhich adds to the cost if you choose to heat your greenhouse with this method.\n\n\n\nOne advantage of electric heaters is that they will always work,\nas long as you have electricity connected and the power doesn\u2019t go out.\n\n\n\nOne disadvantage of electric heaters is the potential for\nuneven heat distribution. An electric\nheater works by convection. This means\nthat it warms the air in a room, which then moves around the room to heat up\nother objects.\n\n\n\nUse An Infrared Heater To Heat Your Greenhouse\n\n\n\nAnother option to heat your greenhouse using electricity is by\nusing an infrared heater. An infrared\nheater uses radiation to warm plants (similar to how the sun warms them up), as\nopposed to the convection used by other electric heaters.\n\n\n\nWhen choosing a heater, make sure to purchase one with the\nright safety features.\n\n\n\nFor example, choose a model with a metal grille to prevent\nthe heating element from coming in contact with flammable objects. If possible, choose a model that also has overheat\nprotection, which turns off the unit if it gets too hot.\n\n\n\nOne idea is to buy an infrared heater that can be mounted on the ceiling or supports of your greenhouse. This will give the same effect as a \u201cminiature sun\u201d inside the greenhouse. You can check out a ceiling mount portable infrared heater on Home Depot website.\n\n\n\nYou can also choose a unit that stands on the floor, such as this infrared heater on the Amazon website.\n\n\n\nUse A Warming Mat For Seed Germination\n\n\n\nOne other option to make your greenhouse warm enough for\ngermination is a warming mat. These mats\nare often used to keep a small amount of soil warm enough for seeds to\ngerminate.\n\n\n\nThese mats are not really meant to heat the entire\ngreenhouse, but rather, to raise the temperature of the soil enough so that\nseeds that need more heat can germinate properly, or so that young seedlings\ncan survive until spring.\n\n\n\nYou can check out a seedling heat mat on the Johnny\u2019s Selected Seeds website.\n\n\n\nHow To Heat A Greenhouse Without Electricity\n\n\n\nMaybe your greenhouse does not have electricity and you don\u2019t\nwant to run an extension cord outside. \nIn that case, there are still some options to heat your greenhouse.\n\n\n\nUse A Gas Heater To Heat Your Greenhouse\n\n\n\nYou have the option of using a heater powered by gas instead\nof electricity to heat your greenhouse. \nThere are gas heaters that use propane or kerosene, and you can often\nchoose vented or non-vented models.\n\n\n\nThe obvious advantage is that you don\u2019t need to provide\nelectricity to run a gas heater.\n\n\n\nOne disadvantage of a gas heater is that you will need to\nkeep it filled with fuel - more so in the coldest months when they will be\nrunning almost constantly.\n\n\n\nAnother disadvantage of gas heaters is that some of these\nmodels will need to be vented outside. \nThis adds another potential source of heat loss in your greenhouse.\n\n\n\nUse A Wood Or Pellet Stove To Heat Your Greenhouse\n\n\n\nIf you don\u2019t want to deal with gas, a wood or pellet stove\nis another option to heat your greenhouse.\n\n\n\nOne advantage of a wood stove is that you can use branches\nor cord wood harvested from your own property.\n\n\n\nOne disadvantage of a wood stove is the smoke that is\nproduced, along with the obvious danger of burning down your greenhouse due to\nopen flame.\n\n\n\nMake A Compost Pile In Your Greenhouse To Heat It Up\n\n\n\nA compost pile can heat up to a temperature of 170 degrees\nFahrenheit (76.7 degrees Celsius). When\na large compost pile really gets going, it can generate enough heat to warm up\nthe air inside your greenhouse.\n\n\n\nA compost pile can generate some heat to warm up your greenhouse in the winter, but only if you feed the bacteria with new material!\n\n\n\nYou can continue to add both brown (carbon-rich) and green\n(nitrogen-rich) materials to your compost pile throughout the winter to keep\nthe bacteria working to produce heat.\n\n\n\nI would not rely on this method alone to heat your\ngreenhouse in the winter. However, when\ncombined with some of the other suggestions outlined here, a compost pile can\nmean the difference between survival and death for the plants in your\ngreenhouse.\n\n\n\nBuild Your Greenhouse On The South Side Of Your House\n\n\n\nThis trick is not as useful if your greenhouse is already\nbuilt. However, if you are thinking of\nrebuilding or upgrading to a larger greenhouse, then it may be worthwhile.\n\n\n\nWhen you build your greenhouse right next to the south side\nof your house, you get two benefits.\n\n\n\nFirst of all, the greenhouse will get the maximum amount of\nsun (assuming you are in the northern hemisphere).\n\n\n\nSecond, the greenhouse will absorb some of the heat from\nyour house, allowing you to save on heating costs for the greenhouse itself\n(electricity or gas).\n\n\n\nHow To Retain Heat In A Greenhouse\n\n\n\nIt\u2019s one thing to heat up your greenhouse, but keeping the\nheat inside is just as important. Here\nare some ways to retain the heat that you generate inside your greenhouse.\n\n\n\nUse Water Barrels To Retain Heat In Your Greenhouse\n\n\n\nPlacing water barrels in your greenhouse will help to retain\nheat, especially if you paint the barrels black.\n\n\n\nWhen the sun hits the barrels, it will warm up the barrel\nitself and the water inside. As the sun\ngoes down and temperatures drop, the warm water will start to release its heat\nto the air inside the greenhouse.\n\n\n\nThe water in a barrel will retain heat from the sun and release it after nightfall to keep the greenhouse warmer.\n\n\n\nAs an added bonus, these barrels can be used for easy\nwatering of seeds, seedlings, and plants in your greenhouse. Just make sure to keep the barrels full to\nmake sure that you get the maximum benefit from the sun\u2019s energy.\n\n\n\nUse Stones Or Cinder Blocks To Retain Heat In Your Greenhouse\n\n\n\nYou can also use stones or cinder blocks to retain heat in\nyour greenhouse. Although not as\neffective as water, stone will still retain some heat from the sun and release\nit as temperatures drop after nightfall.\n\n\n\nEither stones or cinder blocks will work (the darker the\nbetter).\n\n\n\nUse Insulation To Retain Heat In Your Greenhouse\n\n\n\nBy insulating the walls of your greenhouse, you can retain\nthe heat energy from the sun.\n\n\n\nBubble wrap is one good choice to insulate against the cold\nair outside and to trap heat inside. \nTraditional bubble wrap used in packaging and shipping can work, but you\ncan find bubble wrap specifically for greenhouses at garden supply centers or online.\n\n\n\nBubble wrap is one option for insulating the walls of your greenhouse to retain heat.\n\n\n\nYou can also use reflective foil insulation from Amazon, which contains air bubbles but also reflect more of the radiant heat in a greenhouse.\n\n\n\nUse Caulking To Seal Cracks And Openings In Your Greenhouse\n\n\n\nA quick way to keep your greenhouse warmer is to us caulking\nto seal any cracks or holes from nails, screws, or at joints where the\ngreenhouse was put together.\n\n\n\nUse caulking to seal any cracks or holes in your greenhouse and keep the heat inside where it belongs!\n\n\n\nIf you need to vent a heater, make sure to caulk around the\nopening to prevent cold air from coming in.\n\n\n\nUse Row Covers Or Cloches To Cover Plants Inside Your Greenhouse\n\n\n\nIf the above steps just aren\u2019t enough by themselves, then you\ncan use row covers or cloches to offer another layer of protection to the\nplants in your greenhouse.\n\n\n\nA cloche doe not need to be this fancy - you can use a plastic water bottle to keep plants a little warmer in the winter.\n\n\n\nA row cover is made of fabric and is used to protect an\nentire row of plants by insulating them from cold. A cloche is often made of plastic and is used\nto protect one small plant or seedling from the cold (it can also retain\nmoisture).\n\n\n\nFor more information, check out my article on how to protect your plants from cold and frost.\n\n\n\nConclusion\n\n\n\nBy now, you have some idea of how to heat your greenhouse,\nwhether you have electricity connected or not. \nYou also know how to retain the heat that you generate from the sun or\nfrom electricity.\n\n\n\nI hope this article was helpful \u2013 if so, please share it\nwith someone who can use the information. \nIf you have any questions about how to heat a greenhouse, please leave a\ncomment below.