Creating a bountiful garden is the dream for many homeowners. However, unpredictable weather and limited growing seasons can make this difficult to achieve. That's where poly tunnels can be a game-changer.
What is a Poly Tunnel?
A poly tunnel, also known as a poly greenhouse, hoop house or high tunnel, is a tunnel made from polyethylene (plastic) that covers a garden bed or small plot of land. Poly tunnels look similar to miniature greenhouse structures.
Poly tunnels provide many benefits for growing fruits and vegetables:
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Extended growing season – Adding a few weeks at the beginning and end of the normal outdoor growing season. This allows you to get a head start on planting and growing your crops.
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Frost protection – Poly tunnels help protect tender plants from frosts and freezes. This means you can grow plants that normally couldn't survive your winter.
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Weather protection – Plants are shielded from heavy rains, wind, hail and snow. Less waterlogged soil and broken stems.
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Pest protection – Barriers against insects, rodents, birds and other creatures that may eat or damage plants.
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Increased warmth – The interior of a poly tunnel is warmer than outside. This warmth speeds up growth.
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Higher yields – Crops tend to grow faster and produce greater quantities within a poly tunnel.
For gardeners with limited space, poly tunnels allow you to maximize production in a small area. They are especially useful for urban and patio gardens with confined growing zones.
Poly Tunnel Designs and Materials
There are a few basic designs for small-scale poly tunnels:
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Hoop style – Curved PVC pipes or hoops create a rounded roof. The simplest and most affordable option.
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Ridge and furrow – A peaked roof shape like a triangle. Provides more headroom and strength than the hoop style.
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Caterpillar tunnel – Metal or PVC hoops connected by a straight center ridge pole. Allows easy access and ventilation.
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Gothic arch tunnel – Very tall arched ceilings offer maximum space but require more materials.
The covering of the tunnel frame is usually polyethylene plastic sheeting at least 150-200 microns (6-8 mil) thick. Look for UV-stabilized and infrared blocking sheeting that provides maximum longevity and frost protection. Common sizes are 12 to 20 feet wide and any desired length.
For the base, you can install posts directly in the ground or use modular connecting raised beds. Having a solid foundation prevents the tunnel from blowing away in high winds.
Where to Position Your Poly Tunnel
When siting your poly tunnel, choose a level, well-drained area. Full sun is ideal, especially for warmth-loving vegetables. Partial shade can work for greens and root vegetables.
For productivity, orient the tunnel with the length running east to west. This maximizes light exposure on the sides when the sun is low in winter. Avoid shaded areas near buildings, trees and fences.
Easy access to a water source is crucial. Installing rain gutters to collect water is recommended. Place your tunnel within reach of a spigot or setup.
What to Grow in a Poly Tunnel
Many types of edibles thrive in the warm, protected environment of a poly tunnel. Focus on heat-loving crops that benefit most from the extra warmth and early start. Some top choices include:
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Tomatoes – More varieties and larger harvests.
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Peppers – Sweeter with less risk of frost damage.
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Cucumbers – Grow earlier and produce greater yields.
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Melons – Reliable crops less prone to mildew.
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Summer squash – Extremely prolific growth.
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Pole beans – Extended harvest period.
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Strawberries – Bigger berries over a longer season.
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Herbs – Faster growth for multiple cuttings.
With the higher temperatures, you can also try growing exotic or tropical crops like okra, eggplant and sweet potatoes. Don't forget leafy greens, lettuces, spinach, kale and chard for winter and spring harvests.
Growing Medium Options
What will you plant your crops in inside a poly tunnel Most gardeners use raised beds or containers. This avoids soil compaction and drainage issues.
Raised beds are typically filled with a soilless potting mix or compost blend. You can also try hugelkultur beds layered with rotting wood. This retains moisture and adds nutrients as the wood slowly breaks down.
For containers and pots, look for a lightweight soiless mix with good aeration and water retention. Incorporate controlled-release fertilizer to provide steady nutrients over time.
Other mediums like coconut coir, perlite, vermiculite, peat moss and compost can be blended into both raised bed soils and potting mixes. Include a small percentage of perlite or vermiculite to improve drainage in clay and compacted soils.
Manually Ventilating your Poly Tunnel
Proper ventilation is key for healthy plant growth and preventing diseases in a poly tunnel. Stagnant, overly humid air can create big problems.
Ventilation options for small poly tunnels:
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Roll up the sides and doors during the day. Close at night to trap warmth.
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Install zippered flaps at both ends that can be opened.
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Add mesh screen panels that roll down on hot days.
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Use exchange fans placed at opposite ends to circulate air.
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Remove end panels completely and use insect screening.
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Prop open vents along the roof to let rising warm air escape.
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On sunny days, use shade cloth to prevent overheating.
Getting consistent airflow prevents high humidity and heat buildup. Monitor conditions closely and ventilate based on the weather and plant needs.
Automated Poly Tunnel Ventilation
For larger poly tunnels or added convenience, install automated vents and tunnel fans. These systems provide ventilation without daily manual labor.
Vents
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Motorized flap vents react to temperature changes. Open when hot, close when cold.
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Automated roll-up side vents controlled by a thermostat or remote.
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Linear actuators that open rooftop windows or panels when triggered.
Fans
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Circulation fans with thermostatic or humidity-sensing controls.
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Solar-powered exhaust fans remove heat through roof vents.
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Big wall-mount fans offer maximum airflow.
Automated controls are affordable and take the guesswork out of venting. Just set your desired conditions and let the system maintain the ideal microclimate.
Heating Your Poly Tunnel in Winter
Cold winter temperatures limit what you can grow in a poly tunnel. Adding a heating system expands possibilities and prevents frost damage.
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Electric heaters – Portable units with thermostats or in-line greenhouse models.
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Propane heaters – Standalone propane convection or infrared radiant heaters.
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Waste oil heaters – Burn used motor oil in specialized tunnel heater models.
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Compost heating – Decomposing organic matter in buried pipes releases warmth.
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Solar heat storage – Use passive solar panels to collect and store heat.
Any supplemental heat source should be properly sized, vented and secured. Only operate attended heaters to prevent risks.
Providing Water and Irrigation in Poly Tunnels
Plants need consistent moisture to thrive in a poly tunnel's hot, dry conditions. You have several options:
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Hand watering with hoses, water cans or buckets. Simple but time-consuming.
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Drip irrigation on a timer provides slow, targeted watering.
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Overhead sprinklers mounted inside the structure for full coverage.
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Rainwater harvesting using gutters and barrels to supply irrigation.
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Passive sub-irrigation like capillary mats, trays or tubes supply moisture.
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Automatic condenser units pull water from the air to irrigate.
A combination of drip lines and manual watering tends to work best. Make sure to provide sufficient drainage too.
Advantages of Poly Tunnels vs Greenhouses
Both poly tunnels and greenhouses allow season extension and protected growing environments. But there are some key differences:
| Poly Tunnels | Greenhouses |
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| Less expensive to build | More costly to construct |
| Don't require permanent foundations | Usually fixed buildings |
| Manual ventilation | Often have automated systems |
| Temporary structures | Long-lasting permanent structures |
| Focus on annual crops | House perennials and woody plants |
| Unheated | Can integrate heating systems |
| Limited temperature control | Precise climate control |
For many home gardeners, poly tunnels offer an affordable way to reap the benefits of protected growing spaces. They are the perfect solution for small-scale vegetable and herb production.
Resources for Poly Tunnel Growing
Here are some useful resources if you want to learn more about poly tunnel gardening:
Websites and Online Guides
- Four Season Tools Poly Tunnel Guide – Covers planning, building, growing tips and more.
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Homestead and Survival Poly Tunnel Tips – Great basics including height, covering materials, and construction.
Youtube Channels
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Learn Organic Gardening at GrowingYourGreens – Excellent educational channel with poly tunnel videos.
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Richard Perkins UK Polytunnels – Professional grower demonstrates tunnel techniques.
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>Huw Richards – Polytunnels – Practical advice for hobby poly tunnel growers in the UK.
Books
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The Polytunnel Handbook by Andy McKee and Mark Gatter – The polytunnel bible covering all the basics.
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The Polytunnel Book by Joyce Russell – Guidance for beginners including planning and crop selection.
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The Greenhouse and Hoophouse Grower's Handbook by Andrew Mefferd – Applicable tips for any protected growing structure.
Bring the Benefits of Poly Tunnels Home
Installing a poly tunnel over your patio vegetable garden is one of the smartest investments you can make. These inexpensive structures allow earlier planting, faster growth, higher yields and season expansion. They are perfect for urban and small-space gardens. With so many advantages, every gardener should consider adding a poly tunnel.
Transform your Outdoor Space with Patio Furnishings
After reading about the benefits of poly tunnels, you may be inspired to grow more fruits, vegetables and herbs right at home. A productive garden starts with the right structure. But you also need comfortable and stylish patio furnishings to relax and enjoy the fruits of your labor.
The Patio Furnishing experts are here to help transform your outdoor living area into an oasis. Browse our wide selection of high-quality patio furniture, patio umbrellas, outdoor dining sets, patio gazebos, and everything else you need for outdoor leisure and entertaining. Discover top brands, stylish designs, and durable materials built to withstand the elements.
Let your imagination run wild as you create a comfortable, inviting ambiance in your personal patio paradise. A poly tunnel green house surrounded by chic, relaxing patio furnishings makes the perfect backyard retreat. Grow your garden and style your outdoor living space with Patio Furnishing!
