Frost Cloth vs. Row Cover: Which to Buy

Frost cloth and row cover are both spunbonded garden fabric; the difference is weight. Light covers let most sunlight through and add a little warmth, heavy ones protect against frost but block more light. Here's how to pick a weight and size.

FrostCal earns a commission from purchases through these links, at no cost to you. As an Amazon Associate FrostCal earns from qualifying purchases.

Same fabric, different weights

Garden stores sell "row cover," "frost cloth," "frost blanket," and "garden fabric" as if they were different products. They're all the same kind of material: a thin, spunbonded fabric that lets water and some light through while trapping heat rising from the soil. What changes is the weight, listed on the package in ounces per square yard (oz/yd²). Lighter fabric is usually sold as row cover; heavier fabric as frost cloth.

What each weight does

Utah State University Extension gives these typical figures:

University of Wisconsin–Madison Extension notes that heavyweight covers give 4–8°F of freeze protection, and that they're the ones durable enough to reuse for several seasons.

Which one to buy

• One roll for most gardens: a medium weight around 0.5–0.9 oz/yd². Light enough to leave on cool-season crops for days at a time, heavy enough for an ordinary frost night.
• For protecting tomatoes, peppers, and other tender plants on frost nights: a heavy frost cloth (1.5–2.0 oz/yd²). It blocks too much light to leave on for long, so cover in the evening and uncover in the morning.
• For pests, not cold: the lightest insect-barrier weight. It keeps cabbage worms and squash pests off without overheating plants in summer.

On a hard-freeze night you can also double up a lighter fabric for extra protection, so one roll can cover both jobs in a pinch.

How much to buy

Fabric laid directly over plants needs to reach the ground on both sides and have extra to hold down. For width, measure:

bed width + (plant height × 2) + 2 feet

A 4-foot-wide bed of 2-foot-tall plants needs fabric about 10 feet wide. For length, add 2 feet to the bed length so the ends can be tucked and weighted. Over hoops, measure the arc of one hoop from ground to ground and add 2 feet.

Row cover is sold in many widths and lengths. Buying one wide roll and cutting it to size is usually cheaper than several small packs.

Hoops, clips, and weights

• Direct over plants works for sturdy, low crops like greens and carrots. Leave slack so plants can grow.
• Over hoops is better for tall or tender plants and for anything you'll cover for weeks. Wire or fiberglass hoops every 3–4 feet hold the fabric off the leaves, where frost damage happens on contact. Snap clamps keep fabric on the hoops in wind.
• Hold the edges down with soil, boards, rocks, or sandbags every few feet. Utah State Extension suggests weights about every 3 feet. Pins and staples can tear lightweight fabric.

Mistakes to avoid

• Covering too late. Put covers on before sunset so they trap the day's soil heat. See how to protect plants from frost.
• Plastic touching leaves. Plastic sheeting conducts cold; leaves touching it can freeze. Use fabric, or keep plastic on hoops off the plants.
• Leaving heavy covers on in sun. Heavy fabric and plastic can overheat plants on a sunny day. Vent or remove them once it's above freezing.
• Forgetting pollinators. Squash, cucumbers, and melons need bees. Remove covers once they start to flower.

Know when to cover

Covers do the most good on the handful of nights around your first and last frost. Your city's page shows the typical, safe, and risky frost dates so you know when to keep a roll handy. Look up your ZIP code.

Sources

• Row Covers, Utah State University Extension
• Floating Row Cover, University of Wisconsin-Madison Extension