In the 1950s, the invention of polyethylene (plastic) revolutionized agriculture. This affordable, lightweight material became a popular alternative to expensive glass greenhouses. The polytunnel—or plastic-covered hoop tunnel—was born, combining plastic sheeting with flexible or rigid supports to create a durable, protective environment for plants. Polytunnels have become an essential tool for gardeners and farmers worldwide, providing the opportunity to extend growing seasons, protect crops, and optimize yield.

Polytunnels have a variety of uses in both vegetable and ornamental gardening. Whether you’re trying to protect tender seedlings, grow cool-season crops, or create a controlled microclimate, this versatile tool can enhance your garden in many ways.

• Hoops: These can be made of PVC pipes, metal tubing, or flexible fiberglass rods.
• Rebar (optional): PVC pipes can be slid over rebar inserted into the ground for additional strength when creating the frame if desired.

• Plastic Sheeting: Use UV-stabilized, transparent polyethylene for best results.

• Clips for plastic(optional): To attach the plastic securely to the hoops. If using over wooden raised bed, plastic can be secured with a staple gun, but leave some gaps for access and ventilation. 
• Metal C-clips (optional): Can be attached to the inside or outside of raised beds for insertion of the hoop ends if preferred or if unable to insert ends directly in the ground.
• Stakes, Sandbags, Landscape Ties, or Bricks: To seal the structure and anchor the plastic, and prevent it from blowing away. 
• End Panels or Doors (optional): These can help control ventilation and temperature inside.

• Location: If your bed is not already built, choose a sunny, flat area in your garden. Ensure it’s sheltered from strong winds. A north to south orientation is preferred.

• Create the Frame: Insert the ends of the hoops (or your rebar) into the soil at regular intervals (about 3 to 4 feet apart) bending them to achieve the height/width you desire. The height and length will depend on the size of your growing area and plants. 
• Our hoop tunnel kits allow you to construct the frame quite easily--just insert the anchors and connect the rods. They can be adjusted somewhat for height and width by how deeply you bend the rods, and can be customized in length if necessary by cutting the final top rod. We offer these in 3-, 4-, and 6-hoop styles, as well as separate pieces to customize your own.  All you need to provide is the plastic covering.

• Attach the Plastic: Drape the plastic sheeting over the frame and secure it with clips if you desire. Make sure it's tight enough to resist wind but not so tight that it tears. Use stakes or sandbags to weigh down the plastic along the sides.

• Add Ventilation: If your polytunnel gets too hot, your plants will suffer. Leave gaps at the ends or install a zip-up door for airflow. Clips can come in handy here to roll up and secure the front of the plastic when ventilation is needed.

• Remove Weeds: Clear out any weeds to prevent them from competing with your crops.

• Add Compost or Manure: Boost soil fertility by adding well-rotted organic matter. This is especially important in the fall, as cooler temperatures slow down nutrient availability.

• Loosen the Soil: If your soil is compacted, aerate it with a garden fork to improve drainage and root growth.

• Watering: Check the soil moisture regularly, especially on warmer fall days. A drip irrigation system or soaker hose can help maintain even moisture. Especially with crops like lettuce, avoid leaving water on the leaves when cold nighttime temperatures are expected.

• Fertilizing: Since plants continue growing in a tunnel, they’ll need nutrients. Use a balanced, slow-release fertilizer or organic compost tea every few weeks to keep them fed through the extended season.
• Ventilation - Watch the Temperature: Keep an eye on nighttime temperatures. If your polytunnel starts to get too cold, consider adding an extra layer of plastic or even row covers inside for insulation.  On the other hand, warm daytime temperatures may literally cook your crop, which is extremely detrimental to plants that need cooler temperatures like lettuce and brassicas, and could cause bolting. On warm, sunny days you should ventilate if temperatures are above 55 degrees, but replace the cover at night.

Although polytunnels protect from many pests, the warm, humid environment can encourage others

• Aphids: Check for these small sap-sucking insects on leaves, especially in warmer conditions.
• Slugs and Snails: Moist environments attract these pests. Set up traps or use copper tape barriers to keep them at bay.
• Powdery Mildew: Polytunnels can trap humidity, leading to fungal issues like powdery mildew on plants. Ensure proper ventilation and avoid overwatering and wetting foliage.
• Botrytis (GreyMold): Watch for grey mold on plants, especially in crowded conditions. Regularly harvest as necessary to promote airflow.

• Containers can be grouped together under a polytunnel and surrounded with straw, pine needles, mulch, or other insulating material. 
• Adding large stones, bricks, concrete blocks, or basins of water will increase the thermal mass inside the structure--these materials will absorb the heat during the day and release it slowly at night.  This can be done to help regulate temperature whether plants are in the ground or pots.