Ask SAM: Catch your drift

This column is provided by Larimer County Extension's Small Acreage Management (SAM) Program to assist rural residents.

Dear SAM,

Snow keeps drifting onto my driveway. I'm tired of clearing it, only to find the driveway covered again a few days later. How can I control the drifting?

Pete L.

Dear Pete,

Most of us are happy to see some moisture fall from the sky, but we're not always happy with where the moisture settles.

Snow is carried by the energy of the wind. When the wind is blocked by a structure, the snow falls to the ground. Snow fences can be used to cause drifts to form where you want them and not on your driveway.

Whether you're using manufactured snow fence or trees and shrubs as a living snow fence, fence location and height will determine where the snow lands.

The distance between the snow fence and the protected area should be 35 times the height of the fence. A 6-foot high fence needs to be placed at least 210 feet (6 multiplied by 35) from the roadway or building you are protecting from drifts.

For maximum effectiveness and economy, build a single tall fence instead of several shorter fences. A 6-foot fence will trap as much snow as two parallel 4-foot fences.

Place the fence perpendicular to the prevailing wind direction. Our prevailing winds are from the northwest. Build the fence longer than the area you are trying to protect to account for shifts in wind direction.

Snow fences should have 40 to 50 percent porosity. This means about half of the face of the fence should be open space. Pre-constructed snow fence will be designed with this porosity. If you are building your own fence, leave spaces between the slats equal to the width of the slats.

Do not extend the fence to ground level. Leave a 6- to 8-inch gap at the bottom of the fence.

If you don't want a snow fence as a permanent fixture on your landscape, you can roll the fence and place it in storage. You will need sturdy posts for attaching the temporary fence.

Living snow fences of trees and shrubs, similar to windbreaks, are an attractive alternative to constructed fence. They may take several years to grow to an effective size, however. Consider installing a temporary wood or plastic fence upwind from a new planting. Place the constructed fence so the drifting snow will fall next to the planted seedlings. Melting snow will water the trees, which will help them to grow more quickly.

For more details on snow fence design, see the Snow Fence Guide published by the Strategic Highway Research Program at www.trb.org/publications/shrp/SHRP-H-320.pdf.

SAM

Have a question about rural living? Write to Ask SAM, Larimer County Cooperative Extension, P.O. Box 543, Fort Collins, CO 80522.