Should I Cover Plants Tonight?

When It Makes Sense

• Good fit: A sudden temperature drop is forecasted for the night, especially when temperatures are expected to fall below the critical threshold for tender annuals or newly transplanted perennials.
• Good fit: A light frost warning is issued for a specific micro‑climate (e.g., a low‑lying garden bed that cools faster) and you have breathable, frost‑protective material such as horticultural fleece on hand.

When You Should Avoid It

• Warning sign: The forecast calls for warm, dry conditions with no risk of frost; covering can trap humidity and promote fungal growth on leaves.
• Warning sign: You lack a proper breathable cover (e.g., using plastic sheeting without ventilation) which can overheat plants during unexpected warm spells and cause heat stress.

Pros and Cons

Pros

• Provides a temporary barrier against cold temperatures, reducing the risk of frost damage for sensitive species.
• Shields plants from nocturnal wind that can desiccate foliage and increase transpiration stress.

Cons

• Improper covering can retain moisture, creating an environment conducive to fungal diseases such as powdery mildew or root rot.
• Setting up and removing covers each night requires time and labor; over‑use may become habitually unnecessary, leading to wasted resources.

Decision Checklist

• Is there a credible forecast of temperatures near or below the plant’s tolerance level for tonight?
• Do you have a breathable, appropriate‑size cover (e.g., horticultural fleece, lightweight row cover) that can be secured without crushing foliage?
• Will covering create excess humidity or limit airflow for the duration it will remain in place?

Alternatives to Consider

If you decide against covering, you can still protect plants by: moving potted specimens to a sheltered location, mulching around the base of perennials to insulate roots, or using windbreaks such as temporary screens. For a small frost risk, simply brushing off any existing dew and allowing the natural night temperature to decline may be sufficient.

Final Recommendation

Cover plants tonight when a reliable forecast predicts temperatures near or below the critical limit for your species, and when you can use a breathable material that won’t trap excess moisture. In mild or warm conditions, skip the cover and consider mulching or relocation instead. Always monitor weather updates and be prepared to adjust. For high‑value or rare plants, or when uncertainty remains high, consult a local horticultural extension or professional gardener.