Whether you are a new or experienced gardener, you might be\nwondering what a hoop house is, and what they are used for. I was wondering the same thing, so I did some\nresearch to find out.\n\n\n\nSo, what is a hoop house? \nA hoop house is a semi-circular tunnel\nstructure, used to grow plants in a protected microclimate. A hoop house allows you to control the\ntemperature, humidity, and ventilation inside the structure by using doors or\nflaps.\n\n\n\nLet\u2019s take a closer look at hoop houses, including what they\nare for, how they work, what they are made of, and how much they cost. We will also see how hoop houses are\ndifferent from greenhouses, and when you might want to choose each one.\n\n\n\nWhat Is A Hoop House?\n\n\n\nA hoop house (also called a high tunnel or polytunnel) is a\nrectangular tunnel structure with a semi-circular roof. It is tall enough to walk in, so that you don\u2019t\nneed to hunch over. In fact, many\nfarmers build hoop houses that are tall enough to accommodate farming equipment\ninside.\n\n\n\nA hoop house is warmed by the sun and cooled by the wind,\nand it also has a door and vents that can be opened or closed as needed. This allows you to create a \u201cmicroclimate\u201d\ninside of the structure to grow a particular crop based on its need for temperature,\nhumidity, and ventilation.\n\n\n\nA hoop house is warmed naturally by the sun, and usually does not contain any heating or cooling equipment like a greenhouse would.\n\n\n\nYou can also use cloches or row covers inside a hoop house\nto provide an additional layer of insulation to protect plants from cold.\n\n\n\nFor more information, check out my article on how to protect plants from cold and frost.\n\n\n\nYou can also choose different materials for the \u201cskin\u201d or\nwalls and ceiling of the hoop house, depending on how much light you want to\nlet in to the structure. You can change\nthe skin depending on the season, to protect sensitive plants from too much\nlight when the sun is strong.\n\n\n\nA hoop house is usually 14 to 21 feet (4.2 to 6.4 meters)\nwide, and they can be as long as a few hundred feet (100 meters). Hoop houses are often portable and perhaps\nmodular, so that they can be moved easily to cover crops that need protection.\n\n\n\nFor more information, check out this article on hoop houses (polytunnels) from Wikipedia.\n\n\n\nWhat Is The Purpose Of A Hoop House?\n\n\n\nA hoop house has several purposes, all of which are aimed at\nhelping gardeners and farmers to get a better yield per acre of land.\n\n\n\nA hoop house can be used to extend the growing season by\nwarming the air and soil inside the structure. \nTemperatures inside a hoop house are warmer than the outside air, often by\n4 to 6 degrees Fahrenheit (2.2 to 3.3 degrees Celsius).\n\n\n\nThis makes a hoop house a good place to harden off seedlings\nin the spring, especially if you live in a cooler climate with a shorter\ngrowing season.\n\n\n\nA hoop house is also helpful for keeping plants alive that could\nnot otherwise survive the winter, by protecting them from cold, wind, rain, and\nhail. A hoop house can even serve to\nprotect livestock from winter weather.\n\n\n\nA hoop house can be used to protect plants or animals from the weather. Image by Brian Johnson and Dane Kantner. Image from: https:\/\/commons.wikimedia.org\/wiki\/File:Pigs_in_hoop_house,_Polyface_Farm.jpg\n\n\n\nIn addition, a hoop house helps to control moisture levels\nin the soil and humidity levels in the air. \nOn dry, windy days, you can close the doors and flaps of the hoop house\nto prevent water from evaporating out of the soil.\n\n\n\nFinally, a hoop house can be used as a shade house if you\nuse different material for the skin, or covering. For example, you can use material that does\nnot allow much light or heat through to grow cool weather crops, such as\nlettuce, when temperatures rise in the summer.\n\n\n\nA hoop house lets you manipulate the inside environment to create\na microclimate. This microclimate will\nhave the perfect temperature, humidity, ventilation, and light levels to grow a\nparticular crop.\n\n\n\nHow Do Hoop Houses Work?\n\n\n\nA hoop house works similarly to a greenhouse. The sun\u2019s light goes into the hoop house through transparent covers (ceiling and walls), heating up the soil and air inside.\n\n\n\nA hoop house works just as a greenhouse does, by trapping heat from sunlight in the air and soil.\n\n\n\nThe heat then becomes trapped inside the hoop house, taking longer to escape and keeping the air and soil inside the structure warmer than outside.\n\n\n\nThink about how warm a car or house can get on a sunny day with no clouds, even if it is windy outside, and you will have a better idea of how a hoop house works.\n\n\n\nA hoop house also allows air to circulate via doors and\nopenings in the structure, which can be opened or closed to allow for changes\nin temperature or humidity.\n\n\n\nWhat Are Hoop Houses Made Of?\n\n\n\nHoop houses are made of many different materials, including\nmetal, wood, and plastic.\n\n\n\nImage by Dwight Burdette. Image from: https:\/\/commons.wikimedia.org\/wiki\/File:Interior_of_a_Hoop_House_on_the_Farm_at_Saint_Joe%27s,_Superior_Township,_Michigan.JPG\n\n\n\nA common way to start building a hoop house is to drive metal\npoles into the ground at a 30 degree angle, pointed towards the top of the hoop\nhouse.\n\n\n\nFrom there, put lengths of hollow plastic pipe over the\nmetal poles, bending them to form the curved tunnel of the hoop house. Lengths of new 2-inch diameter PVC pipe are\nrecommended for this step. Older lengths\nof PVC pipe are more likely to become brittle with age, and are more likely to crack\nor break instead of bending.\n\n\n\nOnce the PVC semi-circles (hoops) are in place, use lengths\nof wood for baseboards along the ground. \nThis wood will form an outline around the entire hoop house structure.\n\n\n\nNext, run tubular braces along the length of the hoop house\n(attached to the PVC hoops) for extra support and irrigation.\n\n\n\nThen, attach a plastic greenhouse cover to the structure to\nact as a skin. Be sure to install this\nplastic cover when there is no wind, and make sure you have helpers available.\n\n\n\nIt is recommended that you use a polyethylene greenhouse cover,\ntreated with a UV inhibitor. These are\nguaranteed to last 3 years, while an unprotected plastic cover will break down\nwithin a year due to sunlight damage.\n\n\n\nFinally, you can use plywood or greenhouse plastic to make\nthe walls to close in the ends of the structure. Make sure to mark a space on the plywood or\nplastic for a door, and cut it out before attaching the ends.\n\n\n\nFor more information, check out this article from New Mexico State University on building a hoop house.\n\n\n\nHow Much Does A Hoop House Cost?\n\n\n\nA hoop house costs anywhere from $0.75 to $3.00 per square\nfoot, so a larger hoop house will cost more. \nOf course, costs will vary depending on the material used for the hoop\nhouse, and whether you perform the construction labor yourself or hire someone\nto help.\n\n\n\nTo get an idea of the materials you will need, you can check out this article from New Mexico State University. Note that the prices listed are from 2005, so while the materials are still valid, the prices will not be.\n\n\n\nYou can also check out this article from the University of Arkansas on constructing a metal hoop house and this article on hoop house prices and types from the USDA.\n\n\n\nWhat Is The Difference Between A Hoop House And A Greenhouse?\n\n\n\nSo far, it sounds like hoop houses and greenhouses are very\nsimilar. However, there are several key\ndifferences between a hoop house and a greenhouse.\n\n\n\nFirst of all, a hoop house usually has no heating element or\nventilation fan, instead relying on sun and wind to heat and cool the air and\nsoil inside. A greenhouse is often\nheated and cooled by fans or a heating unit.\n\n\n\nAlso, all of the plants in a hoop house are grown directly\nin the ground. The plants in a greenhouse\nmay be grown in the ground, or they may grow in raised beds, pots, grow bags,\ntrays, or other containers on tables or benches within the greenhouse.\n\n\n\nA greenhouse, like the one shown here, will often have plants grown on raised beds, tables, or benches. A hoop house grows plants directly in the ground. Image by Dwight Burdette. Image from: https:\/\/commons.wikimedia.org\/wiki\/File:Interior_of_a_Hoop_House_on_the_Farm_at_Saint_Joe%27s,_Superior_Township,_Michigan-2.JPG\n\n\n\nIn addition, a hoop house does not use reflective ground\ncover, since all of the plants are growing in the ground. A greenhouse will often contain reflective\nground cover to reflect reflects heat onto seeds growing in trays on raised\ntables.\n\n\n\nFinally, a hoop house is much more affordable than a\ngreenhouse. Since a hoop house does not\ncontain heating or cooling elements, it does not need an electrical connection.\n\n\n\nFurthermore, there is no need to spend additional money on\nbenches, containers, reflective ground covers, or other gardening equipment,\nsince everything in a hoop house is grown in the ground.\n\n\n\nFor more information, check out this article on hoop houses from the BTL Liners website.\n\n\n\nHow To Pollinate Flowers In A Hoop House\n\n\n\nThere is one more thing to remember about hoop houses: the\nplants inside still need to be pollinated in order to produce fruit and\nvegetables! If the hoop house is always\nclosed off, there is no way for this to happen.\n\n\n\nYou need to open the doors or windows of your hoop house to allow bees and other pollinators inside if you want your flowers to yield fruit!\n\n\n\nTo solve this problem, open the door or window of the hoop\nhouse on a warm day to allow bees inside. \nYou may also want to plant some attractive flowers nearby to bring the\nbees to the area, where they can easily find the hoop house.\n\n\n\nOne exception is self-pollinating plants, such as tomatoes. You can hand pollinate tomatoes with a\ntoothbrush (among other things), without help from bees or other pollinators.\n\n\n\nFor more information, check out my article on how to hand pollinate tomato plants.\n\n\n\nConclusion\n\n\n\nBy now, you know what a hoop house is, and why you might use\none in your garden. You also have an\nidea of what materials to use to build a hoop house.\n\n\n\nI hope you found this article helpful. If so, please share it with someone who can\nuse the information. If you have any\nquestions about hoop houses, please leave a comment below.