Low Limbing Trees

“I speak for the trees!” said the Lorax.

Though it can often seem we’re the anti-Lorax, in fact wildfire mitigation can make the forest that surrounds your home much healthier. Depending on the location, you can often retain healthy conifers around your home by low limbing

courtesy of University of Idaho Extension

them instead of removing them altogether. But it’s important that you remove branches properly to preserve the health of the tree while reducing your wildfire risk.

If you’ve had an assessment recently, you’ve probably seen this important item (Remove branches 6-10 feet from the ground) show up under Zone 1 or Zone 2. So why does low limbing make a difference in terms of protecting your home against wildfires? Low hanging branches on conifers can provide “ladder fuel” to bring the fire up into the crown of the tree. Branches close to the ground can catch fire from a grass or surface fire, and create a torching, running fire in the tree tops. The goal of wildfire mitigation is to keep the fire to the ground so that fire behavior is less extreme and won’t ignite your house on fire. If you’ve maintained a noncombustible barrier around your house, a fire on the ground will stop short of reaching your house altogether.

To reduce this chance of fire getting into the tree, we often recommend removing the branches on your conifers that are within 6-10 feet of the ground. This is something that can easily be done by most homeowners themselves with a hand or limbing saw. Most times, you won’t even need a ladder to prune the branches. But it’s very important to use proper technique so that you don’t affect the tree’s overall health. The tree will react to the removal of the branch like a wound and will grow over the cut. But to do so, it needs to be able to produce enough energy through photosynthesis, making food from sunlight. If you remove too many of the branches, it won’t be able to heal its pruning “wounds.” Removing branches improperly could cause permanent damage.

The rule of thumb it to remove no more than a 1/3 of the tree’s height. If the tree is more than 30 feet tall, removing branches 6-10 feet off the ground makes sense. But for a smaller tree, you will want to reduce that number. For example, with a a 12-foot tree, you’ll want to only take the branches 3-4 feet off the ground. As trees grow, you’ll want to continue to re-check them each year to see if more limbing is required to reduce wildfire risk.

Winter is a great time to limb or prune conifers as they are dormant. Their “wounds” are less likely to be infested by insects since they are gone for the season and thereby will heal faster. Before beginning any forestry task, including low limbing, make sure to use proper safety gear. Safety glasses are a must so that branches or saw dust don’t get in your eyes. If you are cutting larger branches, a helmet can help protect your head from injury as well.

When removing longer branches, it’s best to make several cuts. Your first cut should be under the branch 8-12 inches out from where the branch attaches to the trunk. The second cut should be on top of the branch a couple inches further out so the branch snaps leaving just the stub. The third and final cut should be made just outside the branch collar, the swollen part of the branch where it connects to the trunk. When you limb properly, this collar will grow over the wound and seal it off.

Low limbing can create a lot of slash on your property. If you are low limbing during winter, it’s important to pile your slash a good distance from your home to reduce wildfire danger. We recommend staging it outside Zone 2 (100 feet away from your house) for safety. While the Boulder County sort yards are closed for the season, you do still have a couple of options for getting rid of slash during the winter. Western Disposal in Boulder has a yard waste area that remains open and will accept slash for a discounted fee for Boulder County residents. Boulder County offers free burn permits to county residents to burn slash when certain conditions are met. If you are thinking of burning your slash, consult their helpful guide and make sure to stage your slash in an open area where it is not directly under trees.

Low limbing is a DIY project that you can learn to master with just a little practice. Proper limbing of your conifers can help reduce your wildfire risk, and help keep your trees healthy for years to come.