Can You Cover Plants With Plastic Bags?

Covering plants with plastic bags is a common practice among gardeners looking to protect their plants from frost pests and diseases. But is it really safe for the plants? Here we’ll take an in-depth look at the pros and cons of using plastic bags as protective plant covers.

Why Do Gardeners Cover Plants With Plastic Bags?

There are a few main reasons gardeners use plastic bags to cover plants

• Frost protection – Plastic traps heat and creates a warmer microclimate to shield plants from freezing temps overnight

• Pest/disease control – Plastic barriers can help contain infestations and prevent spread to other plants.

• Excess rain protection – Bags keep heavy downpours from oversaturating the soil and rotting plants.

• Temporary greenhouses – Clear plastic bags allow light in while providing humidity and warmth.

So in theory, plastic bags seem like an easy solution for protecting plants in cold weather or adverse conditions. But how well do they really work?

Potential Risks of Covering Plants With Plastic Bags

While plastic bags can provide some protection, there are also risks to be aware of when using them to cover plants:

• Direct contact with foliage can worsen freeze damage as moisture condenses and ice forms on leaves.

• Lack of air circulation under plastic causes humidity to get too high, promoting fungal and bacterial diseases.

• Excessive heat buildup during daytime when light passes through clear plastic, leading to plant stress.

• Flapping and billowing plastic in wind loses insulating ability and damages plants.

• Can blow away easily or be weighed down onto plants if not secured properly.

• Not a substitute for cold frames or greenhouses that allow ventilation.

Best Practices for Using Plastic Bags as Plant Covers

If using plastic bags as a last resort, here are some tips to reduce risks:

• Avoid contact with foliage – use stakes or hoops to drape bag over without touching.

• Open bags up or cut ventilation holes to prevent excess moisture buildup.

• Use white or opaque bags to diffuse light intensity rather than clear plastic.

• Double bag or use heavy trash bags for better insulation.

• Weigh down edges securely so wind doesn’t blow away.

• Monitor temps and remove plastic during day to prevent overheating.

• Use for overnight frost protection only, not long cold snaps.

Better Alternatives for Protecting Plants

While plastic bags can work in a pinch, they aren’t the best solution. Some better options for plant protection include:

• Fabric sheets – Softer and more breathable than plastic. Excellent insulation.

• Frost blankets – Designed for cold weather use while allowing airflow.

• Burlap – Coarse weave protects from frost but prevents moisture buildup.

• Newspaper – Multiple layers provide surprising insulation.

• Cardboard – Another readily available material to block wind and cold.

• Towels/blankets – For smaller potted plants that are easy to wrap up.

• Cold frames – Mini greenhouse structures with warmer microclimates.

• Mulch – Insulates roots and crowns against frost heaving.

The key is to provide insulation while still allowing ventilation. Paper, cloth, and other permeable materials work better than plastic for this.

Quick Tips for Covering Container Plants

Potted plants need a bit different protection than those in the ground:

• Place pots together to conserve heat, then cover group.

• Wrap pots in burlap or foam insulation before covering plants.

• Bring containers into garage or greenhouse if possible.

• Use strings of outdoor lights under plants for warmth.

• Construct small cold frames around individual pots.

Covering the roots is just as important as the tops for container plants. Insulate the whole plant or move it into a protected space.

Emergency Use of Plastic for Plant Protection

While not ideal, plastic bags can be used in a pinch:

• Drape open bags over plants without direct contact.

• Weigh down edges securely with stones, bricks, etc.

• Double bag or use dark plastic for more warmth retention.

• Add a second layer like burlap over the plastic.

• Place warm water containers among plants for added heat.

• Monitor closely and remove immediately if condensation forms.

When a surprise frost is predicted and no other covers are available, plastic can provide some emergency protection. Just use precautions to minimize risks to plants.

Key Takeaways on Covering Plants with Plastic

To summarize:

• Avoid plastic contact with foliage and allow ventilation.

• Use plastic only when other covers are unavailable.

• Secure edges carefully and check for heat/moisture buildup.

• Remove plastic during daytime to prevent overheating.

• Insulate entire containers, not just plant tops.

• Fabric, newspapers, cardboard, and other permeable materials are better choices.

• Improvise protection only in emergencies, not for extended cold periods.

With smart usage, plastic bags can provide some cold weather protection in a pinch. But better options like breathable fabric sheets, commercial plant covers, and mini greenhouses will safeguard your plants while reducing risks.