How to Get Rid of Groundhogs With Ammonia

Soaking rags in household ammonia and stuffing them into groundhog burrow entrances can drive the animals out temporarily, but the effect fades fast and rarely solves the problem for good. Ammonia’s sharp fumes irritate a groundhog’s sensitive nose and airways, making the burrow uncomfortable enough that the animal leaves. The trouble is that the chemical evaporates quickly outdoors, the groundhog often returns within days, and repeated applications raise real concerns for your soil, your pets, and your own lungs. If you want to try ammonia as a first step, you can, but understanding its limits will save you from the cycle of re-soaking rags every few days with nothing to show for it.

Why Ammonia Bothers Groundhogs

Groundhogs, like most rodents, rely heavily on their sense of smell to navigate burrows, detect predators, and find food. Ammonia is what scientists call a “sensory irritant,” meaning it triggers an immediate burning sensation in the nose, eyes, and upper airways. Research on rodents exposed to ammonia vapor found that breathing pattern changes were rapid in onset, consistent with upper respiratory tract irritation, and reversed quickly once exposure stopped.¹ That quick reversibility is the key detail: the discomfort is real but temporary. Once the fumes dissipate, the irritation is gone, and the animal has no lasting reason to avoid the area.

Chronic exposure paints a different picture. Mice exposed to ammonia for four hours a day over four weeks developed actual damage to their olfactory systems, including inflammation that altered their foraging and anxiety behaviors.² But that kind of sustained, daily exposure doesn’t happen when you toss an ammonia-soaked rag into a burrow. Outdoor conditions ensure the fumes thin out long before they could cause the chronic irritation that might permanently discourage a groundhog from returning.

How to Apply Ammonia in and Around Burrows

If you want to give ammonia a try, the method is straightforward. You need standard household ammonia (the kind sold for cleaning, usually around 5 to 10 percent concentration), old rags or towels you don’t mind throwing away, and optionally some loose soil or crumpled newspaper to plug the entrance after you place the rags.

Start by identifying all the burrow entrances. Groundhog burrows typically have a main entrance with a mound of excavated dirt and one or more escape holes that are flatter and easier to miss. Walk the perimeter of your yard, garden beds, and along any fence lines or foundations looking for openings roughly the width of a softball or larger. Missing even one exit means the groundhog can simply avoid the ammonia-treated entrance and come and go through another hole.

Soak several rags thoroughly in ammonia and push one into each entrance, getting it as far down the tunnel as you can with a stick or broom handle. Then loosely pack dirt or newspaper over the opening. The goal is to trap the fumes inside the tunnel system long enough to make the groundhog uncomfortable enough to leave through whichever exit you’ve left open, or to abandon the burrow entirely. Some people leave one exit unplugged on purpose so the animal has an escape route; others seal everything and hope the groundhog digs its way out elsewhere. Leaving an exit is generally the safer and more humane approach.

Repeat the process every two to three days. You’ll need to, because ammonia doesn’t linger in soil the way you might expect.

Why Ammonia Fades So Quickly Outdoors

Ammonia is a gas dissolved in water. When that water evaporates, the ammonia goes with it, and outdoors in warm weather, evaporation happens fast. Research on ammonia volatilization from soil found that the rate ammonia escapes into the air follows different dynamics than water evaporation but is not slowed down meaningfully by differences in soil texture, moisture, or humidity.³ In practical terms, that means even if you pour ammonia directly into damp soil at the burrow entrance, it doesn’t stick around. Sandy soil, clay soil, wet conditions, dry conditions — the ammonia volatilizes regardless.

This is the fundamental problem with ammonia as a groundhog deterrent. You’re applying a substance whose defining physical behavior is to turn into a gas and float away. On a hot, breezy summer afternoon, the window of effective repellency inside a burrow might be measured in hours, not days. A groundhog that left in the morning could comfortably return by evening.

Habituation and Why Repellents Lose Their Edge

Even when a chemical odor is strong enough to repel a rodent at first, repeated exposure often leads to the animal simply getting used to it. Research on volatile compounds tested as rodent repellents has shown mixed and sometimes surprising results: some predator-derived chemicals that should theoretically frighten prey animals turned out to have no significant effect, or even attracted the animals rather than repelling them.⁴ The broader lesson from repellent research is that rodents are adaptable. An odor that triggers alarm the first time becomes just another part of the environment if the animal encounters it repeatedly without any actual threat following.

Ammonia isn’t a predator scent, so it doesn’t carry the same fear cues, but it shares the same vulnerability to habituation. A groundhog that associates the smell with temporary discomfort but no real danger learns to tolerate it, especially if the burrow is well-established and the animal has already invested significant effort in the tunnel system. Groundhog burrows can be extensive, sometimes stretching over 40 feet with multiple chambers, and an animal is reluctant to abandon that infrastructure over a bad smell that comes and goes.

Safety Risks for You and Your Household

Before you pour ammonia anywhere on your property, take the safety concerns seriously. Ammonium hydroxide solutions are alkaline and cause severe irritation or chemical burns to the eyes, skin, and respiratory system on contact.⁵ Household-strength ammonia is dilute enough that brief skin contact isn’t usually an emergency, but getting it in your eyes or inhaling concentrated fumes in a poorly ventilated space can cause real harm. Wear gloves, avoid splashing, work outdoors, and stand upwind when soaking the rags.

The bigger concern for many homeowners is pets. Dogs are notorious for investigating burrow entrances, and cats will sometimes explore tunnel openings as well. Ammonia inhalation is acutely dangerous to cats in particular. Research exposing cats to ammonia gas at high concentrations found that the initial insult can be fatal, and even when it isn’t, secondary effects can produce chronic respiratory dysfunction that persists long after the exposure.⁶ Those lab concentrations were far higher than what a rag in a burrow would produce, but a curious cat sticking its face directly into a freshly treated tunnel entrance could inhale a concentrated pocket of fumes. Keep pets away from treated burrows entirely, and if that isn’t practical, ammonia probably isn’t the right approach for your yard.

One critical mistake people make is mixing ammonia with bleach or other chlorine-based cleaners, sometimes thinking it will create an even stronger deterrent. That combination produces chloramine gas, which is toxic to humans and animals alike. Never combine ammonia with any other chemical for pest control purposes.

What Ammonia Does to Your Soil and Plants

Ammonia doesn’t just vanish harmlessly when it leaves the rag and enters the ground. In soil, ammonia and its ammonium form can damage plant roots directly. Research on ammonia toxicity in soil found that concentrated zones of ammonia killed root tissue, stopping root elongation and causing progressive decay working backward along the root.⁷ The toxic zone extended several centimeters from the source in those experiments. If you’re pouring ammonia near your vegetable garden, flower beds, or the root zones of trees and shrubs, you’re risking exactly this kind of damage.

Beyond direct root injury, ammonia changes soil chemistry. It raises pH locally, making the soil more alkaline. That pH shift affects the microbial communities that keep soil healthy. Research has shown that altering soil pH significantly changes both the diversity and the activity of microorganisms involved in the nitrogen cycle.⁸ A single application probably won’t wreck your garden, but repeated drenching of the same area over weeks can create a dead zone where beneficial microbes are suppressed and plant roots struggle. If you’re trying to protect a garden from groundhog damage, repeatedly poisoning the soil with ammonia is counterproductive in a way that’s easy to overlook.

Approaches That Work Better Than Ammonia

Ammonia occupies an awkward middle ground: it’s irritating enough to bother a groundhog but not persistent enough to keep one away, and its side effects on soil, plants, and pets make repeated use impractical. If you’re dealing with a groundhog that has already established a burrow, more reliable strategies exist.

Hardware cloth or welded wire fencing buried at least a foot deep around gardens is the most consistently effective barrier. Groundhogs are strong diggers, so the buried portion matters as much as the above-ground fence. Bend the bottom of the buried section outward in an L-shape, roughly 12 inches wide, to discourage digging under. The above-ground portion should be at least three feet tall and, if possible, left floppy at the top rather than attached to a rigid rail. Groundhogs are decent climbers but struggle with fence tops that flex under their weight.

Live trapping and relocation is legal in many areas but check your local regulations first, because some states restrict or prohibit relocating wildlife. Baiting a cage trap with cantaloupe, broccoli, or fresh peas near the burrow entrance typically works within a few days. Relocating the animal at least five miles away reduces the chances of it returning, though success varies and a new groundhog may eventually move into the same burrow.

For homeowners who need professional-grade results, exclusion devices installed over burrow entrances allow the groundhog to leave but prevent re-entry. Once the animal is confirmed out, the burrow can be collapsed and filled. This is often the approach used by licensed wildlife control operators, and it avoids the chemical concerns entirely.

When Ammonia Might Still Make Sense

Despite its limitations, ammonia isn’t completely useless in every scenario. If you’ve spotted a groundhog that has just started exploring your property and hasn’t yet built an established burrow, a strong deterrent applied early might convince it to move on before it invests the effort of digging. The animal hasn’t yet formed a strong attachment to the site, so the bar for discouragement is lower. Soaking rags and placing them at the exploratory holes, combined with removing food attractants like fallen fruit or accessible garden crops, can sometimes tip the balance.

Ammonia can also serve as one piece of a layered approach. Pairing it with physical exclusion (fencing your garden while also treating the burrow entrance) addresses both the immediate nuisance and the long-term access problem. The ammonia provides short-term disruption while the fencing provides the permanent barrier. Used this way, you don’t need the ammonia to work indefinitely; you just need it to buy you time while you install the real solution.

Where ammonia consistently fails is as a standalone, long-term fix. The homeowner who keeps re-soaking rags every few days for weeks on end is fighting the chemistry of evaporation, the biology of habituation, and the stubbornness of an animal that has nowhere better to go. At that point, you’re spending more effort on the ammonia than it would take to install a fence or set a live trap. If two rounds of ammonia treatment haven’t persuaded the groundhog to leave, it’s time to escalate to a method with a better track record.

Groundhog Burrow Complications Worth Knowing About

One reason ammonia and other repellents underperform against groundhogs specifically is the complexity of their burrow systems. A typical groundhog burrow isn’t just a single tunnel. It’s a branching network with separate chambers for sleeping, hibernating, and even a designated latrine area. The total length of tunnels can be substantial, and the multiple entrances and exits create airflow patterns that dilute any chemical you introduce at one point.

This ventilation effect is essentially working against you. A burrow with two or three openings acts like a chimney: air moves through it naturally, carrying ammonia fumes out rather than letting them build up to concentrations the groundhog finds unbearable. Plugging all but one entrance helps, but groundhogs can re-open a plugged entrance or dig a new one surprisingly fast, sometimes within a single night. Their front claws are adapted for excavation, and moving loose soil or newspaper out of a tunnel opening is trivial work for them.

The depth of the burrow matters too. Main chambers can sit several feet underground, where temperatures stay relatively cool and stable. An ammonia-soaked rag placed at the surface entrance might produce strong fumes in the first few inches of the tunnel but fail to push irritating concentrations all the way down to where the groundhog actually rests. The physics of gas diffusion in a long, winding underground passage aren’t on your side. Professional fumigants used by licensed operators work partly because they are denser than air and settle downward into burrow systems, a property that household ammonia, which is lighter than air, does not share.