ints:greenhouses

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ints:greenhouses [2025/11/30 17:12] – asimongints:greenhouses [2025/12/17 04:30] (current) – external edit 127.0.0.1
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 Greenhouses and polytunnels are permanent or semi-permanent structures made of transparent material such as glass or plastic that protect plants from the cold and wind. They allow through the whole spectrum of sunlight, but trap the (infra-red) radiation that is reflected from the earth or plants (plus the warmed air is prevented from mixing with cooler air from above), which causes temperatures to rise. Carbon dioxide also allows sunlight through, but traps reflected infra-red radiation from the earth - which is why it's called a '[greenhouse gas](http://en.wikipedia.org/wiki/Greenhouse_gas)'. Greenhouses and polytunnels are permanent or semi-permanent structures made of transparent material such as glass or plastic that protect plants from the cold and wind. They allow through the whole spectrum of sunlight, but trap the (infra-red) radiation that is reflected from the earth or plants (plus the warmed air is prevented from mixing with cooler air from above), which causes temperatures to rise. Carbon dioxide also allows sunlight through, but traps reflected infra-red radiation from the earth - which is why it's called a '[greenhouse gas](http://en.wikipedia.org/wiki/Greenhouse_gas)'.
  
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 The cultivation of plants under controlled conditions within structures has been practiced since Roman times, but greenhouses proper arrived in Europe after the Renaissance and massively increased in number in the UK in the 19th century. They're now much more affordable. In rural or suburban areas, domestic greenhouses around 2-3 metres long are common in gardens. Polytunnels are cheaper per cubic metre than greenhouses, and therefore tend to be used for larger-scale growing. The cultivation of plants under controlled conditions within structures has been practiced since Roman times, but greenhouses proper arrived in Europe after the Renaissance and massively increased in number in the UK in the 19th century. They're now much more affordable. In rural or suburban areas, domestic greenhouses around 2-3 metres long are common in gardens. Polytunnels are cheaper per cubic metre than greenhouses, and therefore tend to be used for larger-scale growing.
  
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 Greenhouses can be of traditional wood and glass (the more environmentally-friendly but more expensive option) or of polycarbonate sheet and aluminium frame. They can also be made of unusual materials like recycled plastic bottles or lego. They can be free-standing, pop-up or lean-to (against the house or a wall). Polytunnels are free-standing, and usually made of polyethylene sheet stretched over a semi-circular frame of steel or aluminium tubes. Greenhouses can be of traditional wood and glass (the more environmentally-friendly but more expensive option) or of polycarbonate sheet and aluminium frame. They can also be made of unusual materials like recycled plastic bottles or lego. They can be free-standing, pop-up or lean-to (against the house or a wall). Polytunnels are free-standing, and usually made of polyethylene sheet stretched over a semi-circular frame of steel or aluminium tubes.
  
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 High-tech, experimental greenhouses have been developed, that can involve technologies such as: soap-bubble shading/reflecting (to capture warmth in winter and reflect excess heat in summer); trapping surplus daytime heat in heat-stores for slow release at night; internal recycling of water to reduce usage; hydroponics / aeroponics / aquaponics to maximise yields and minimise use of water, energy, time and space. High-tech, experimental greenhouses have been developed, that can involve technologies such as: soap-bubble shading/reflecting (to capture warmth in winter and reflect excess heat in summer); trapping surplus daytime heat in heat-stores for slow release at night; internal recycling of water to reduce usage; hydroponics / aeroponics / aquaponics to maximise yields and minimise use of water, energy, time and space.
  
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 - You don't get wet in the garden if it's raining - You don't get wet in the garden if it's raining
  
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 Start small: it’s cheap and easy to build your own small structure to get started, and it can be fun to use your creative and practical skills to make something from scratch (from recycled materials). A few poles (old tent-poles will do, or bamboo poles tied together to make an A-frame) and some plastic sheeting is all you need for a miniature polytunnel. You can also get cheap kits from garden centres. Remember that you'll need to water regularly, as the plants won't be getting any rain, and that may involve lifting the structure off - but, if you find that your yields increase, you could up-scale to larger structures in subsequent seasons. Start small: it’s cheap and easy to build your own small structure to get started, and it can be fun to use your creative and practical skills to make something from scratch (from recycled materials). A few poles (old tent-poles will do, or bamboo poles tied together to make an A-frame) and some plastic sheeting is all you need for a miniature polytunnel. You can also get cheap kits from garden centres. Remember that you'll need to water regularly, as the plants won't be getting any rain, and that may involve lifting the structure off - but, if you find that your yields increase, you could up-scale to larger structures in subsequent seasons.
  
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 There are numerous suppliers of greenhouses, polytunnels and the materials and information required to make them. Search online and you’ll find thousands, or visit your local garden centre. Greenhouses are usually cheaper at the end of the season, in the autumn. Look on [Freecycle](https://uk.freecycle.org/) or other freebie websites, or in the classified section of the local press - although they're usually snapped up quickly, and you'd probably have to dismantle and transport it. There are numerous suppliers of greenhouses, polytunnels and the materials and information required to make them. Search online and you’ll find thousands, or visit your local garden centre. Greenhouses are usually cheaper at the end of the season, in the autumn. Look on [Freecycle](https://uk.freecycle.org/) or other freebie websites, or in the classified section of the local press - although they're usually snapped up quickly, and you'd probably have to dismantle and transport it.
  
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 Here's an idea for a [£30 DIY greenhouse](https://www.permaculture.co.uk/readers-solutions/how-build-%C2%A330-diy-greenhouse) from Permaculture Magazine. Here's [how to buy, dismantle and re-build a second-hand greenhouse](http://lowimpactorg.onyx-sites.io/how-to-buy-dismantle-and-re-build-a-second-hand-greenhouse/), and here's [how to put up a polytunnel](http://lowimpactorg.onyx-sites.io/putting-up-a-polytunnel-fresh-fruit-veg-all-year-round/). Think about tethering it to the ground to prevent damage by strong winds. Incorporating ventilation, and ease of access with a wheelbarrow, into the DIY design would also be a good idea. Here's an idea for a [£30 DIY greenhouse](https://www.permaculture.co.uk/readers-solutions/how-build-%C2%A330-diy-greenhouse) from Permaculture Magazine. Here's [how to buy, dismantle and re-build a second-hand greenhouse](http://lowimpactorg.onyx-sites.io/how-to-buy-dismantle-and-re-build-a-second-hand-greenhouse/), and here's [how to put up a polytunnel](http://lowimpactorg.onyx-sites.io/putting-up-a-polytunnel-fresh-fruit-veg-all-year-round/). Think about tethering it to the ground to prevent damage by strong winds. Incorporating ventilation, and ease of access with a wheelbarrow, into the DIY design would also be a good idea.
  
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 Staging can add height and tiers so that you can grow more food in the same space. You'll need ventilation (pests can proliferate in still air) and in summer it may get too hot. A greenhouse can have roof windows, and polytunnels flaps that open at the ends. We wouldn't recommend heating, as the environmental benefits of using the structure would be wiped out. If a crop needs a heated greenhouse, grow something else. Staging can add height and tiers so that you can grow more food in the same space. You'll need ventilation (pests can proliferate in still air) and in summer it may get too hot. A greenhouse can have roof windows, and polytunnels flaps that open at the ends. We wouldn't recommend heating, as the environmental benefits of using the structure would be wiped out. If a crop needs a heated greenhouse, grow something else.
  
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 With a greenhouse or polytunnel, you can have fresh green leaves like mizuna, rocket and lettuce all through the winter. It's impossible to buy anything that tastes like fresh green salads you've just picked, and is one of the best arguments for having a greenhouse. In early spring you can germinate plants such as French beans in the greenhouse earlier than you would outdoors (before planting them outdoors later in the season). You can follow this with tomatoes, aubergines, peppers and cucumbers. You can sow French beans in pots in august, then bring the pots inside to have beans in october and november. The strawberry season can be hugely increased, and you can plant a grapevine at the north end (so that it doesn't cast a shadow over other crops). With a greenhouse or polytunnel, you can have fresh green leaves like mizuna, rocket and lettuce all through the winter. It's impossible to buy anything that tastes like fresh green salads you've just picked, and is one of the best arguments for having a greenhouse. In early spring you can germinate plants such as French beans in the greenhouse earlier than you would outdoors (before planting them outdoors later in the season). You can follow this with tomatoes, aubergines, peppers and cucumbers. You can sow French beans in pots in august, then bring the pots inside to have beans in october and november. The strawberry season can be hugely increased, and you can plant a grapevine at the north end (so that it doesn't cast a shadow over other crops).
  
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-Propagating [**seeds**](http://lowimpactorg.onyx-sites.io/lowimpact-topic/seed-saving/) in trays in a greenhouse in the early spring, before transferring to a cold frame, then planting outside.+Propagating [**seeds**](/seed/seed_saving) in trays in a greenhouse in the early spring, before transferring to a cold frame, then planting outside.
  
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 Of course your greenhouse or polytunnel will need regular watering, as it isn't getting any rain. Watering can or hose is the easiest solution, but it's labour intensive. There are several kinds of automated systems, such as drip irrigation (on top of the soil), seep hoses (under the soil) or water timers between your tap and your hose. The bigger your structure, the more useful an automated system will be. It's best to irrigate in the evening, so that the water has time to soak into the soil without evaporating. Of course your greenhouse or polytunnel will need regular watering, as it isn't getting any rain. Watering can or hose is the easiest solution, but it's labour intensive. There are several kinds of automated systems, such as drip irrigation (on top of the soil), seep hoses (under the soil) or water timers between your tap and your hose. The bigger your structure, the more useful an automated system will be. It's best to irrigate in the evening, so that the water has time to soak into the soil without evaporating.
  
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-[Geodesic dome](http://lowimpactorg.onyx-sites.io/categories/geodesic-domes) greenhouses tend to lose less heat at night because they have the minimum of surface area for the internal volume of air.+[Geodesic dome](/geod/geodesic_domes) greenhouses tend to lose less heat at night because they have the minimum of surface area for the internal volume of air.
  
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-You can find more detailed advice about greenhouses & polytunnels in books or online (see resources) - and here are [month-by-month guides](http://lowimpactorg.onyx-sites.io/categories/greenhouses-polytunnels/further-info) to what to sow, plant and harvest in your polytunnel or greenhouse.+You can find more detailed advice about greenhouses & polytunnels in books or online (see resources) - and here are [month-by-month guides](/grho/greenhouses-polytunnels) to what to sow, plant and harvest in your polytunnel or greenhouse. 
 + 
 + 
 +## Further resources 
  
  
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 [[p:David Coton]] of [GardenSite](https://www.gardensite.co.uk/)  [[p:David Coton]] of [GardenSite](https://www.gardensite.co.uk/) 
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  • ints/greenhouses.txt
  • Last modified: 2025/12/17 04:30
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