Learn How to Repair Greenhouse Plastic

Being out in all the elements of your region can be taxing on greenhouse plastics, which are out there 24/7 through it all. Greenhouse plastic, designed to last up to ten years, will inevitably sustain damage from sharp objects, branches, tools, and extreme weather like hail or strong winds.  

Over time, exposure to sunlight breaks down the polymers that make up the plastic and causes cloudiness. In the long term, these effects will alter how crops growing inside will perform. 

Identifying the Need for Repair or Replacement

If you’ve been growing in a greenhouse for some time, you may have noticed signs of degradation in your plastic coverings. There are some telltale signs that it needs repairs. 

• Weak spots 
• Yellowing or discoloration 
• Obvious tears or rips 
• Wrinkling 
• Brittle 

While greenhouse coverings are durable and contain UV stabilizers to withstand constant sun exposure, they don’t last forever. Extreme weather, harsh sun, fallen sharp tools, trees, and general bumps and blunders are common ways the plastic can become damaged. 

Avoiding Chemical Damage

Overspray from fertilizers and pesticides can also cause brittleness and yellowing. If you spray or live in an area where drift from nearby fields can land on your plastic, it is essential to wash any chemical residue off your greenhouse plastic immediately. Chemical contaminants like sulfur or chlorine left on the plastic will void the manufacturer’s warranty. If you missed a spot or found the damage later, you can use the steps below to fix it. 

Greenhouse Plastic Inspection Checklist

It is essential to complete an inspection of your greenhouses and high tunnels each spring and fall for repair needs and general issues. You can refer back to this data at any time. 

Make a checklist for easy high tunnel inspections, including: 

• A brief visual inspection 
• Check doors, windows, and end walls are in working order
• Inspect plastic for small and large tears and rips 
• Gauge the cloudiness of the plastic 
• Check spring wire and lock channels
• Look for any gaps and holes that seep air 

Related: Greenhouse plastic

Essential Tools and Materials

It’s a good idea to always have these items on hand once you have a high tunnel or hoop house installed so you’re not caught in a bind when damage inevitably occurs. 

• Greenhouse plastic repair tape or woven plastic repair tape, which you select, depends on the type of greenhouse plastic you have. 
• Sharp scissors or a razor knife with a new blade
• Soapy water 
• A towel to dry the plastic off with 
• 70% rubbing alcohol and a clean cloth or wipes
• A smooth board or thick piece of cardboard to hold behind tears as you work 
• A friend to help keep the plastic pulled taut and the repair tape flat without folds or bubbles. 

Step-by-Step Repair Process

Now that you’ve gathered the necessary tools and materials, let’s walk through how to effectively repair your greenhouse plastic and get it back to protecting your crops.

Preparation

Identify the damage and take measurements. Trim the edges of tears and holes to smooth them out and make for a more seamless repair. Do this on both layers if you are working on a double-layered tunnel. 

If the tear is close to the lock channel, remove the spring wire holding the plastic on enough to allow you access to the tears. If the repair needs to be made near or on the end wall, open up one side of the plastic so you have enough space to fit your hands and the plastic safely through.

Clean around the tears inside and outside the plastic with soapy water where the repair tape will touch. Go several inches past the hole and change your cloth or wipe as needed. Allow the plastic to fully dry before continuing. Wipe down anywhere the tape will touch with rubbing alcohol. 

For Small Tears

Extend the repair tape several inches past the rip in all directions, pressing firmly along the entire edge of the tape adhering it securely. Then, do the same to the opposite side so the tape sticks to itself and the edges of the rip. It helps to have a friend hold a board or cardboard on the opposite side of the plastic as you work. This lets you press firmly and work smoothly to avoid wrinkles and air bubbles. 

For Large Rips and Holes

Follow the same method as for small tears, but overlap the tape more. If the tear is larger than the width of your repair tape, cut a piece of extra plastic as a patch to fill the gap before taping it together. The patch should be two inches wider than the hole on all sides. For large holes, use the reinforcement techniques outlined below. 

For a consistent, smooth edge, ask for a friend’s help. Pull it all very taut before taping and securing it firmly down. Have your friend hold a board or cardboard on the opposite side of the plastic as you work. This allows you to press firmly and work smoothly to avoid wrinkles and air bubbles. Tape all patches on both the inside and outside of the plastic. 

Related Video: Large Greenhouse Hole Repair

Reinforcement Techniques

Once you've completed the initial repair, you can take extra steps to reinforce the plastic, ensuring it holds up longer under various conditions.

Take unused, clean plastic and cut a piece a few inches larger than the hole on all sides. With the help of a friend, hold it in place over the hole and tape it all the way around. Then, go back over the plastic, pulling it taut the entire time. Use multiple layers of tape and interchange the direction the tape is running to reinforce the repair. 

Preventative Measures

With your repair securely in place, it's a good idea to consider some preventative measures that can help extend the life of your greenhouse plastic and avoid future damage.

When installing greenhouse coverings, pulling plastic tightly over the structure is essential to ensure its prolonged life. Plastic coverings that blow around and wrinkle in the wind will not last as long, are more prone to damage, and increase the stress on the structure's frame. 

Checking around the structure seasonally for minor repairs will help keep the plastic in great shape for longer. Also, occasionally cleaning it will allow the best light transmission for the health of crops growing inside. 

Here are a few things to remember to avoid greenhouse plastic damage: 

• Take care when rolling side walls up and down to ensure the plastic remains straight and tight, avoiding gaps, plastic flapping, and future tears. 
• Use the right-sized plastic covering in the first place to ensure a proper fit. 
• Properly store sharp tools and large items that may fall inside or around your greenhouse and avoid large rips.
• Spring wires may loosen in extreme weather, so look for ends that have popped out after big storms, as the plastic in these unsecured areas can easily tear after blowing around in the wind. 
• If you live in a region where heavy snow loads are the norm, clear your greenhouse daily or as needed in winter. The constant weight can cause damaging stress and stretching, leading to a shorter lifespan of the plastic. 
• Avoid friction and make repairs to the frame as needed. 
• Use landscape fabric around the perimeter of your high tunnel to prevent weeds. The most common cause of damage is mowing or weed whacking too close to your sidewalls.

Common Mistakes to Avoid

While taking preventative measures is crucial, avoiding common mistakes during the repair process is equally important. Here’s what to watch out for when repairing greenhouse plastic: Avoid overlooking small tears, using incorrect materials, and ignoring the weather. 

Overlooking Small Tears

Like small weeds become enormous weeds, small tears become enlarged with wear, strong winds, and rain. Under the right conditions, they can grow rapidly. Fix them right away to avoid a more significant issue. 

Using Incorrect Materials

Match the strength of the repair tape to the greenhouse plastic. Otherwise, you’ll likely need to repair the same holes in a few months or a year. Bootstrap Farmer’s repair tape is 150 microns in thickness, equivalent to 6 mil, which will repair damage on 6 mil plastic, which is standard in greenhouses. 

If you have woven plastic like Solarig 156 or Solarig 182 on your greenhouse, use the woven plastic repair tape specifically designed for those products. Use it with batten strapping to hold the plastic in place and reduce stress on the frame. 

Related: Woven Greenhouse Plastic

Ignoring Environmental Factors

Avoid attempted repairs in active precipitation or making repairs in the dead of winter. The tape withstands extreme temperatures from -4°F (-20°C) to 140°F (60°C), chemicals, moisture, chemicals, wind, and abrasions, but you should monitor repairs bi-annually to ensure they’ve held. A warm, cloudy day is ideal for making repairs. 

FAQs

What are the signs of UV damage on greenhouse plastic?

UV rays can cause greenhouse plastic to become cloudy or slightly yellow as the polyethylene breaks down. It will be weak to the touch, and after so many years in the elements, it may become brittle and wrinkled. Bootstrap Farmer greenhouse plastic features a 5-layer technology, is UV-resistant, and has a four-year warranty and guarantee. 

Can I repair greenhouse plastic in cold weather?

Yes, but ensure there is no moisture present. Rain, morning dew, condensation, and melted snow will not allow the tape to hold correctly. Do not make repairs if the temperature is below freezing, as the tape may not secure. 

How often should greenhouse plastic be replaced?

Depending on your region and the quality, your greenhouse plastic should be replaced every 6 to 10 years or as needed for best results. Make replacements in early to late fall before freezing temperatures occur, which could be the breaking point for old, degraded plastics

Related: How to Determine the Size of Greenhouse Plastic You Need

What types of adhesives are safe for greenhouse plastic?

Dedicated greenhouse repair tape is the safest way to make greenhouse plastic repairs; you can rest assured it will withstand the elements. Duct tape, masking tape, or painter’s tape are not UV-rated and will not withstand the elements. 

Is it possible to recycle damaged greenhouse plastic?

Yes. When replacing greenhouse plastic, keep the old stuff and repurpose it for other farm tasks. Cut it into strips to fit over-wintered low tunnels. Use it to solarize a weedy field. Use it to cover trays of cold-stratifying seeds to hold in moisture. Cut it to fit beds of perennials to serve as mulch. Once it’s no longer viable, try contacting the supplier and see about qualifying recycling programs before tossing it in the garbage. Many municipalities allow plastic film recycling if you take it directly to the processing center or waste disposal site. 

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Written by Jenna Rich of Partners’ Gardens LLC