Polyrope Guides • Polytunnels
Winter storms put more strain on a polytunnel than anything else in the gardening year, and most storm damage starts small: a split that was never taped, a door left to swing, a cover that had gone slack over the summer. An hour of checks on a calm autumn day is far easier than chasing a torn sheet across the garden in a gale.
Quick answer: your autumn checklist
- Tape every tear and hole in the cover now, with UV-stabilised polythene repair tape.
- Check the cover is tight and still firmly fixed all the way round, whether it is buried in a trench or held by a base rail or battens.
- Make sure the doors shut fully and can be held closed, and keep doors and vents shut in high winds.
- Clear and tie down anything loose around the tunnel.
- Have fleece ready for tender plants on frosty nights.
- If the cover is past repair, replace it before the worst of the weather.
Why wind is the main risk
A polytunnel cover is a large, light sheet. When it is tight and fixed all round, the wind flows over it. When it is slack, it flaps, and every flap rubs the polythene against the frame and tugs at the fixings. When a door is open or broken, the wind can get inside and push the cover up from underneath. That is why nearly every check below comes back to three things: a tight cover, sound fixings and closed doors.
| Check | What to look for | What helps |
|---|---|---|
| Cover | Tears, holes, worn patches, old repairs lifting | Polythene Repair Tape |
| Tension | Ripples, or a sheet that moves in and out when you push it | Re-firm the trench or tighten the battens |
| Doors and vents | Gaps, loose hinges or latches, no way to hold them shut | Elastic bungee cord or bungee cords with hooks |
| Frame | Bolts and rough edges touching the sheet | Anti Hotspot Tape when you next re-cover |
| Surroundings | Tools, pots, canes and anything light | Put away, or cover and tie down with a tarpaulin |
| Plants | Tender crops on frosty nights | Garden fleece |
| Old cover | Tears all over, or past its UV life | A new 720 gauge or 900 gauge cover |
Step 1: Walk round and inspect the cover
Pick a dry, calm day. Walk slowly round the outside and look at the whole sheet, then go inside: small holes and splits in the roof are easier to spot from inside, against the light. Pay most attention to:
- places where the sheet rests on the hoops and cross bars;
- the edges near the ground and around the door frames;
- old repairs that have started to lift at the corners.
Step 2: Tape tears now, not after the first storm
A small tear grows quickly once the wind gets hold of it, so repair it while it is still small. Our Heavy Duty Polythene Repair Tape is a clear, UV-stabilised tape made for repairing polytunnel and greenhouse covers. It is 48 mm wide, comes in 20 m and 50 m rolls, and its rubber-based adhesive can be applied in very cold conditions: it works from -30°C to +80°C.
Wipe the polythene clean and let it dry, then run the tape well past both ends of the tear and press it down firmly, working out any air. Where you can reach both sides of the sheet, tape the inside as well.
Step 3: Check the tension and the fixings
Push gently on the side of the tunnel. A tight cover barely moves; a slack one ripples or bellows in and out. How you tighten it depends on how your cover is fixed:
- Buried in a trench: check that the soil over the edge of the sheet has not sunk or washed away, and firm it back down along the full length.
- Base rail or timber battens: check that every batten and screw is tight and that the sheet has not pulled out from underneath.
- End walls: check the joins where the cover meets the end frames and door frames.
If a long section has come loose, re-fix it now, following the instructions for your tunnel,.
Step 4: Doors and vents
Doors are often the weak point in a storm. Check that each one closes fully, that the hinges and latches are sound, and that you have a way to hold it firmly shut. In high winds, keep doors and vents closed so the wind cannot get in and lift the cover.
Elastic cord is handy for tying a door or a door flap shut. Our black elastic bungee cord comes in 4 mm to 12 mm diameters, stretches to about twice its length and resists UV. For quick jobs, bungee cords with spiral hooks (54 cm long, 6 mm thick, pack of 6, maximum load 30 kg each) hook straight onto a frame.
Step 5: Look at the frame from inside
While you are inside, look for bolts, joints and rough edges where the sheet rests on the frame. In the wind the cover moves against them and can wear through. Anti Hotspot Tape is a 3 mm foam tape (30 mm × 9 m) that pads rough edges and bolts and helps prevent tears and punctures. It goes on the frame before the cover, so fit it the next time you re-cover the tunnel.
Step 6: Clear the ground around the tunnel
Anything that can blow against the cover can puncture it. Put away tools, pots, canes and trays. Cover any timber or materials stacked outside with a tarpaulin and tie it down firmly.
Step 7: Protect the plants inside
On the coldest nights tender plants may need more than the cover. Our 23 gsm garden fleece is made from UV-stabilised non-woven polypropylene, lets air and moisture through, and can be laid over crops or used as an extra layer inside polytunnels and greenhouses. It comes in 1.6 m wide rolls of 5 m, 10 m and 100 m and cuts to size with ordinary scissors.
When the cover is past repair
If you find tears all over the sheet, or the cover has passed its UV life, a new cover this autumn is a better plan than patching it through the winter. Our 720 gauge covers are UV-stabilised for a minimum of 4 seasons and our 900 gauge covers for a minimum of 10. The 900 gauge film is highly resistant to tearing, puncturing and stretching, and suits tunnels exposed to strong winds.
Our guide Polytunnel Cover Guide: 720 vs 900 Gauge Polythene compares the two, and How to Measure Your Polytunnel for a Replacement Cover shows you how to work out the width and length. Choose a calm, dry day to fit it.
When a storm is forecast, and after it has passed
Before: close and tie the doors and vents, put away anything loose, and take a last look at any repairs.
After: walk round again as soon as it is safe. Tape any new tears straight away and re-firm any edges that have lifted, before the next spell of wind makes them worse.
Frequently asked questions
Should I open the doors to let the wind through?
No. Keep doors and vents shut in high winds, so the wind cannot get inside and lift the cover.
Can I repair the cover in cold weather?
Yes. Our repair tape can be applied in very cold conditions and works from -30°C to +80°C. Make sure the polythene is clean and dry first.
How do I know when the cover needs replacing?
If it is torn in several places, or it has passed the UV life of its grade (a minimum of 4 seasons for 720 gauge, 10 for 900 gauge), plan a replacement rather than more repairs.
Do you deliver?
Yes, with free nationwide delivery in Ireland.
Getting your tunnel ready this weekend?
Stock up on repair tape before the weather turns, and if the cover is past saving, choose a new one in 720 or 900 gauge. Not sure what you need? Get in touch and we will help.