Burlap on Evergreens: When It Helps and When It Hurts

Drive through any northern neighborhood in December and you'll see shrubs wrapped in burlap like mummies. Some of them need it. Some of them don't, and a few are being hurt by it. Here's how to tell the difference and how to do it right.

What burlap protects against

Evergreens keep their leaves or needles all winter, and those needles keep losing water. When the ground is frozen, the roots can't replace it. Wind and winter sun speed up the water loss. The result is winter burn (also called desiccation): needles that turn brown or bronze, usually on the side facing the wind or the south.

Burlap helps with:

• Drying winter wind, especially on exposed corners and open lots.
• Winter sun reflecting off snow onto the south and west sides.
• Road salt spray from plows and passing cars, which browns the side of the shrub facing the street.
• Heavy snow sliding off a roof or being thrown by a plow.

Which shrubs need it

Good candidates:

• Newly planted evergreens in their first one to three winters, before their roots are established.
• Broadleaf evergreens like boxwood, rhododendron, holly, and some azaleas.
• Arborvitae, yews, and hemlocks on windy, exposed sites or near a road.
• Anything planted where salt spray hits it every winter.

Usually don't need it:

• Established, healthy evergreens in a sheltered spot.
• Plants that are rated well for your hardiness zone and have done fine for years.

If a shrub has made it through several winters with no browning, it probably doesn't need burlap.

The screen method: better than wrapping

Wrapping burlap tightly around a shrub is the most common mistake. It can:

• Trap moisture and encourage disease.
• Bend and break branches, especially under snow and ice.
• Rub needles off as it moves in the wind.
• Cook the plant on a sunny day if it's wrapped in dark plastic instead of burlap. Never use plastic.

The better way is a windscreen:

1. Drive wooden or metal stakes into the ground around the shrub (or along the windward and street side of a hedge) before the ground freezes.
2. Staple or tie burlap to the stakes, keeping it a few inches away from the foliage.
3. Leave the top open so air moves and light gets in.
4. Make sure the bottom is secure so snow doesn't pull it down.

For a row of arborvitae along a driveway, one long screen on the street side is often enough.

Tying up for snow

Tall, multi-stemmed arborvitae and junipers can split open under heavy snow. Loosely tie the stems together with soft twine or strips of cloth, spiraling up from the bottom, so they hold each other up. Don't tie so tight that air can't move through the plant, and remove it in spring.

When to put it up and take it down

• Up: after the ground freezes and the plants are fully dormant, usually late November into December. Putting burlap up too early can keep the plant from hardening off.
• Down: in early spring once the worst wind is over and before new growth starts. Don't leave it on through warm weather.

Water first

The best protection is a well-watered plant going into winter. Give evergreens a deep soak in fall, right up until the ground freezes. See water your trees before the ground freezes. A few inches of mulch over the root zone keeps the soil from freezing as deep and holds in moisture.

What about anti-desiccant sprays?

Anti-desiccant (anti-transpirant) sprays coat needles with a waxy film meant to slow water loss. Research results are mixed; some extension services say they help on some plants, others say the benefit is small. If you use one, follow the label and apply on a day above freezing. Water and a windscreen do more.

If your shrub browns anyway

Don't prune brown evergreen foliage right away in spring. Wait until new growth starts; some of the brown areas may still have live buds. Cut out only what's truly dead once you see where the new growth is.

Near a road? See road salt damage on lawns and shrubs for salt-tolerant options and spring fixes.

Related: Planting Trees in Fall in the Northern US