How to Get Rid of Garlic Mustard Before It Seeds

Pull it before the seed pods form. A patch you can clear in an afternoon should be pulled by hand; a stand you cannot clear needs spot treatment on the rosettes, repeated for several years. The reason is the seed bank, not the plant in front of you.

When to pull or spray

Garlic mustard is a biennial. The first year it sits as a low rosette of kidney-shaped leaves. The second year it bolts, flowers and makes seed, then dies.

That two-year cycle is the opening. Penn State Extension says garlic mustard has a taproot and, unlike many invasive perennials, does not regenerate from root fragments. That makes it one of the few invasive plants that can be controlled by pulling.

The catch is the seed. Penn State Extension says plants that are pulled while they have seed pods, even unripe ones, can still develop viable seed. The Wisconsin DNR says to pull in early spring before seed set, and to bag flowering plants for the trash or for burning. Both point to the same rule: pull before the pods form, and bag what you pull.

The calendar is tight. Penn State Extension says flowers open from March or early April into early summer. The seed pods follow in early to mid summer, and once they turn brown and brittle the seed is ready to shatter.

Pull or spray, by the size of the job

The choice is about time, not about which method is stronger. Pulling is the better tool when you can finish before the pods form. Spraying is the better tool when the stand is larger than your available hours.

The seed bank is the real problem

This is where garlic mustard stops being a one-spring task.

• Penn State Extension says the seeds remain viable for over five years in optimal conditions.
• The Wisconsin DNR says seeds remain viable in the soil for at least seven years.

Either number means the same thing for a homeowner: the plants you see this year are not the whole population. Seeds from previous years can germinate after you clear the adults. A single pass creates open ground, and open ground is what the seed bank has been waiting for.

Penn State Extension puts it plainly: individual plants are easy to control, but because of the huge seed banks and season-long germination, clearing one flush may invite another. Persistence and a long-term approach are the key.

What the sources name for herbicide

The active ingredients below are the ones named by Penn State Extension. This page does not give rates, because product strengths differ and the label for your product is the only rate that applies.

• Glyphosate. Penn State Extension says glyphosate has been shown to be effective on garlic mustard even in the dormant season, as long as temperatures are above freezing.
• Triclopyr plus 2,4-D. Penn State Extension describes this as a selective mix that controls most broadleaf plants while leaving grasses unharmed, with little soil activity.
• Pendimethalin. A pre-emergence herbicide that affects germinating seed. Penn State Extension notes it will not control existing plants and will not control a population on its own because germination is staggered.
• Sulfometuron-methyl. Penn State Extension describes it as controlling both existing plants and germinating seed for several months, but also eliminating most desirable herbaceous plants.

Follow the product label; the label is the law. If the label and this page disagree, the label wins. The label also sets the personal protective equipment, and for a selective mix near native plants the label restrictions matter as much as the active ingredient.

Do not bare the soil

Penn State Extension makes the point directly: preserving native groundcover is desirable, because the garlic mustard seed bank will quickly take advantage of bare ground.

So the goal is not “clear everything and start over.” It is:

• Remove garlic mustard.
• Leave the native plants that are already there.
• Pull or spot-treat the new flush rather than digging the site bare.
• Keep returning to the same spots in later springs.

What to do with the material

Bag it and put it in the trash. Do not compost it.

• Penn State Extension says to bag and remove pulled plants from the site, because even early pulling probably includes some plants that have or will develop viable seed.
• The Wisconsin DNR says to place pulled or cut plants in plastic bags for trash disposal, or to burn them where allowed.

The invasive plant disposal guide covers solarizing and local rules.

The one-page plan

1. Find the rosettes in early spring, before the flower stalks rise.
2. Pull the whole crown and taproot, or spot-treat if the stand is too large.
3. Bag everything you pull. Do not compost it.
4. Come back in late summer and fall for plants you missed.
5. Repeat next spring, and the spring after that, until the seed bank stops producing.

That is a multi-year plan. It is also the only plan the seed bank allows.

Related WildScope pages

• Garlic mustard species profile for rosette and second-year identification.
• How to dispose of invasive plants for bagging and trashing.
• When to treat invasive plants for seasonal timing.
• Removal guides for other species.
• Invasive plants in Ohio for the state list and reporting routes.