Landscape Journal: The Value of Burning

The Value of Burning

Intentionally setting fire to a landscape can seem counterproductive. But it’s a useful tool for managing forests, prairies, meadows, and other grasslands. Many of these ecosystems need periodic fire—historically caused by lightning—to set seed and reduce competition from woody species. Fire-adapted species play a key role. Aristida stricta, a grass species found in the Sandhills region of North Carolina, rarely produces seed unless it’s exposed to fire. This grass also burns quickly and keeps the flames moving across the landscape, protecting young pine seedlings from the intense heat of a prolonged fire.

Meadows, prairie, and other sites dominated by grasses benefit from periodic burns. Without fire, some species can take over and eventually reduce the diversity of the planting. For more information on burning for prairie restoration and management, we recommend the excellent blog, The Prairie Ecologist by Chris Helzer. His posts on controlled burning are fascinating.

In Designed Plantings

Even with a designed prairie or meadow, regular burning helps minimize competition and stimulate flowering. It’s a way to sustain and renew the landscape. The Sarah P. Duke Gardens near us in Durham, North Carolina manages a prairie using controlled burns. They have a small, horticultural interpretation of a Piedmont Prairie, an ecosystem dominated by grasses and wildflowers, with scattered oaks. They burned the prairie in mid-March and are on a two- to three-year cycle. You can see images and read about it on their blog post.

Most land managers who use controlled burning do so every two to five years. The appropriate cycle depends on the plant composition, resources, and goals of the planting. If you manage a large area, it’s important not to burn it all at once. Pollinators, small animals, and other wildlife need a refuge from the fire. It’s particularly important if an area is bordered on all sides by roads and wildlife populations have nowhere to go. A good strategy is to divide the area into sections and rotate the burn schedule so that you leave at least one section protected each time you burn. Depending on the size of your site, you may wind up burning every year, but not every section gets burned each year.

Burning Grasses

In addition to mixed plantings like meadows or prairies, large masses of grass can benefit from burning. Not only is it beneficial for many grasses, it’s often the most efficient way to clear an area before the spring flush. At Hoffman Nursery, we burn several large meadow areas, bioswales, sweeps of grasses, and some smaller garden areas.

Typically, the best time to burn is just before new growth comes up. This year we burned late in our gardens. It won’t harm the grasses, but we were curious about the effects of burning at various times. We did some test burns on grasses that had been cut back three weeks ago. They were surrounded by debris and had re-flushed since having been cut. We want to see if those grasses will look or perform differently than those that weren’t cut back.

Any time you are dealing with fire, you must take precautions and pay close attention to the weather conditions and surrounding areas. Burn permits are usually required from local counties or municipalities. We recommend anyone interested in doing controlled burns do the research and know what’s involved before undertaking it. In many areas, agencies such as the Forest Service can provide guidance or even assist in performing the burn.

Q&A

After last month’s blog post we received several questions from readers. Two of those stood out because they’re related to this month’s topic.

Q: Is it okay to burn 1-year-old grasses from Hoffman Nursery?

A: In general, it’s okay to burn young grasses. However, it depends on how well established they are in that first year. If they were well-rooted and had strong growth in their first growing season, then burning them the following spring should be fine. At the nursery, we just burned grasses that have only been in the ground for eight months. They were all well established and looked good, so we think they’ll do just fine.

Q: Can I burn the brown tips of evergreen grasses?

A: This is something we haven’t ever tried, and it’s an intriguing question. Our GrassSolutions garden is the perfect place to try it. This garden features low-growing grasses and sedges used as lawn alternatives. To answer this question, we burned around ten plants each of the following: Juncus tenuis, Eragrostis spectabilis, Bouteloua gracilis, Sporobulus heterolepis, and Carex flacca ‘Blue Zinger’. Our garden team liked how clean those plants looked after burning off the brown tips. We will see if it has any adverse effects on growing during the season. We will share the results with you once we know.

There are many resources about controlled burning and prescribed fire online. A good start is the Coalition of Prescribed Fire Councils, Inc. For those in the Southeast, there’s a helpful resource page from the NC Prescribed Fire Council, our state affiliate.