There are lots of reasons to plant new trees, but sometimes you need to know how to kill a tree. Perhaps a previous homeowner planted a tree too close to the foundation. Maybe unwanted tree seedlings have popped up in inconvenient places around your yard. Maybe someone unknowingly planted a tree that's considered invasive in your area. Or, perhaps you've got a tree that triggers your or a loved one's allergies. Whatever the reason, here's how to kill a tree in your yard so it won't grow back.
Reasons to Kill a Tree
The first thing to do is determine your reason for removing the tree: Is it a lovely tree in the wrong location? Is it messy or invasive? Does the tree lean dangerously and threaten to topple over on people or property? Are too many trees planted in close proximity and restricting healthy growth? Knowing these details can help you avoid similar mistakes in the future.
Of course, there are many ways to accidentally kill a tree, including:
- Too much or too little water
- Too much, or the wrong type of fertilizer
- Compacted soil from vehicles or equipment driving over the root zone
- Damage to the roots or trunk from lawnmowers or string trimmers
- Incorrectly applied chemicals
Killing a tree intentionally is another matter entirely and may require the help of an arborist—particularly if your tree is very large.
A Note on Safety
Wear personal protective equipment (PPE) whenever you work outdoors. A sharp twig in the eye can quickly mean a hospital visit, and sitting in the emergency room waiting for stitches from a nasty cut is a lousy way to spend time that could otherwise be spent gardening. Safety glasses and gardening gloves are usually enough for simple tasks like digging and pruning. Bigger tasks require more PPE, like safety-toe boots or a hard hat, especially if you're working with anything overhead or heavy.
Arboricide (a.k.a., the killing of trees) often involves the use of heavy machinery or chemicals. Always follow manufacturer’s recommendations and instructions when you use equipment or chemicals.
Ways to Kill a Tree on Purpose
The best way to kill a tree you don't want depends on its size. Tree seedlings are relatively easy to remove, but obviously a mature shade tree will require a very different approach.
1. Weed It Out
The seeds of some tree species are easily spread around by the wind or wildlife (such as squirrels and birds). Volunteer seedlings that spring up from these scattered seeds can usually be pulled from the ground by hand or with a standard garden weeding tool such as a hori-hori knife. The earlier you identify the unwanted seedlings, the smaller (and easier to remove) the roots will be. Make a practice of removing unwanted seedlings to ensure you don't end up with harder-to-remove saplings.
2. Dig It Out
If the tree is small enough, the soil is soft enough, and your back is strong enough, the best way to remove a tree is to dig it out.
- If the trunk is 2-3 inches thick and the top of the tree is not tall and heavy, cut the top off around chest height and remove any remaining lower branches.
- Use a sharp spade, shovel, or ax to cut the tree’s roots in a circle around the trunk. The further away from the trunk you dig, the smaller the roots will be. Try digging about 1.5-2 feet away from the trunk to start.
- Once you circle the entire tree, use the trunk as a lever to pry the tree out of the ground. You should be able to feel where any remaining roots are.
- If the tree has a tap root (a root that grows straight down from the bottom), you might need to dig under the tree on one side to sever the tap root with a shovel, hand saw, or hatchet.
- Knock the remaining soil off the root ball with a shovel or trowel and tamp the soil back down into the hole.
- Add some extra soil to account for the loss of the roots. Otherwise, you will have a permanent depression in the ground.
3. Try Girdling or Frilling
Girdling is a traditional method of killing a tree without cutting it down—but it can happen naturally too. Manual girdling involves cutting a ring completely around the tree through the bark and the cambium with a saw. The cambium is the thin layer of cells under the bark that moves water and nutrients throughout the tree. Cut two parallel rings a few inches apart or one ring 2-3 inches wide around the tree. Usually, 1/2-1 inch is deep enough to girdle the tree successfully.
Another option is frilling, which involves a ring of downward-facing cuts with an ax or hatchet around the tree. Severing the cambium is often enough to kill the tree. However, you can follow up frilling (and occasionally girdling) with a water-soluble herbicide sprayed directly into the wound immediately after cutting. This herbicide moves into the tree’s roots, stopping further growth.
One benefit of girdling and frilling is that it leaves standing dead trees. When safely located away from any people or property, these trees become a habitat for nesting wildlife. It also allows the wood to cure for use in the fireplace.
A girdled tree can be left standing for a year to allow the wood to dry, and then be cut to the ground and split for firewood.
4. Cut It Down
Often, a tree is too large to dig out of the ground without massive (and expensive) equipment. In this case, the best option may be to cut it down. Cutting down a tree is a fast way to remove an unwanted plant, but it can also be extremely dangerous. A modest-sized tree’s trunk, branches, and leaves can weigh hundreds or thousands of pounds.
Most trees above 4-5 inches DBH (diameter at breast height, a standard measurement for trees measuring the trunk’s diameter at 4.5 feet above the ground) are very heavy at the top and dangerous to cut down yourself. An ISA-certified arborist or reputable professional tree care service has the experience and equipment to handle the job safely.
Professional arborists can sometimes safely drop a large tree straight to the ground. They may need to climb the tree with ropes and safety gear or use a bucket truck to get into the canopy, where they rig the limbs with ropes to safely lower the heavy pieces of wood to the ground. In some instances, the tree is located such that the only way to remove it safely is with a crane. Contact several reputable tree care services for quotes and to discuss options. Always make sure that your tree care services are insured. Your homeowner’s insurance will not likely cover contractors.
No matter the size of the tree, if you choose to cut down a tree yourself, always wear your PPE and use sharp tools. Sharp tools cut better and are safer to use than dull tools.
Dealing with the Stump
Once the tree is on the ground, you can grind out the remaining stump with a stump grinder or leave the stump to decompose naturally. If you let nature do the job, the decomposition process can take many years. There are, however, products available to speed things up. Visit your local home and garden store to see what is available. Or incorporate the stump into your garden design as a pedestal for planters. You could even hollow the stump out and turn it into a planter.
Be aware that stump grinding is a dangerous job often best left to the professionals. It's an extra expense, but an otherwise healthy tree can often resprout from the stump, creating more work in the future. To stop the stump from resprouting, apply an herbicide labeled for stump or basal bark applications. These chemicals should be used (according to the product label) as quickly as possible after cutting down the tree to be effective. The chemical is then absorbed into the tree’s roots, killing them and halting growth.
Working with Chemicals
Many herbicides are labeled to kill trees and woody brush. Visit your local landscape or garden supply store to see what is available in your region and to discuss the best options for your needs.
In addition to using herbicide when girdling, frilling, or destroying a stump (as previously mentioned), you can consider basal bark herbicide treatments. This involves spraying trees at the base of the trunk with an oil-soluble herbicide. It works best on young trees and trees with thin bark—but don’t expect immediate results. Basal bark treatments can take weeks or months to be effective.
In some cases, such as with invasive trees like the tree of heaven (Ailanthus altissima), simply damaging the tree or cutting it down without herbicide won't finish the job. It may even stimulate hundreds of suckers to grow from the roots. In fact, for extremely vigorous trees like the tree of heaven, even cutting the tree and treating the stump with the proper herbicide won't be enough. In this instance, the “hack and squirt” method is often recommended.
Hack and squirt involves making several downward-facing cuts in a tree with an ax or hatchet without girdling it and then spraying the wounds with an herbicide. This process allows the tree to live long enough to fully absorb the chemical, which should kill it without triggering the sucker growth from the roots.
The Label Is the Law
Don't be tempted by the chemical cocktails “guaranteed” to kill a tree that you may find on the internet. Be aware that all pesticide labels clearly state: “It is a violation of Federal law to use this product in a manner inconsistent with its labeling.” This statement means using or applying the chemical in any way not noted on the label is against the law. The laws are designed to protect both you and the environment when the chemical is used.
For instance, an herbicide product may be legally applied at a specific concentration but illegal in an undiluted form. Sometimes, products with the same active ingredient but different product names each have different labels. One may be legal to apply, while another is illegal for your purposes, even though they are the same ingredients. Herbicide labels are easy to find online and are always attached to the packaging. Do your research to avoid unknowingly breaking the law. It is better to be safe than sorry.
You can find more information about herbicides on the Environmental Protection Agency's website, or by contacting your state’s pesticide regulatory agency to ask about using herbicides in your area.
What to Do with Dead Trees
As challenging as it may be to kill a tree, you still have to deal with the resulting debris—at least in most cases. Dead trees, standing or lying on the ground, are a necessary part of a healthy ecosystem. If it's appropriate for your landscape—and there is no risk of it falling, injuring someone, or damaging something—then consider leaving the dead tree as a habitat for birds and other wildlife. Otherwise, move the downed limbs, trunk, and stump else off your property or relocate it to reap the benefits of dead wood without cluttering up your landscape.
The remaining wood can be split for firewood, burned in an outdoor firepit, chipped in a wood chipper for mulch, or hauled away for disposal. Just keep in mind that not all wood is suitable for burning in a fireplace. If you are uncertain, play it safe, and don’t burn the dead wood in your house. Contact your municipality and waste disposal company for information on preparing the wood for haul-off and disposal.
