Everyone knows what onions are, but what about onion grass? Onion grass is an insidious weed often dismissed as a minor nuisance. But left unchecked, this irritating plant can infiltrate and destroy your lawn in no time.
Whether you’re a lawn care newbie or a seasoned gardener, learn how to identify, eliminate, and prevent onion grass in your lawn.
How to identify onion grass
Also known as wild onion, crow garlic, or wild garlic, onion grass is a perennial weed that typically grows in clumps and produces small pink or white flowers at the top of a long stem. When crushed, its thin, hollow leaves release an unmistakable onion or garlic scent, hence the name. If you catch a garlicky scent while mowing, it’s likely that onion grass is lurking in your grass.
Onion grass is common throughout the United States, including the East, Midwest, and West Coast. It grows most vigorously in cooler temperatures, so you’ll likely encounter this weed type in early spring and fall.
Notorious for its aggressive growth and ability to dominate the yard, onion grass is commonly found along roadsides and in lawns, gardens, and open fields. It likes acidic soils but also can tolerate slightly alkaline conditions. As a weed, onion grass is highly adaptable and can establish itself in a wide range of soil types, including sandy, loamy, and clay soils — as long as they’re well-draining.
Onion grass also has culinary uses. The leaves and bulbs can be used fresh in salads and soups or as a garnish. The leaves, bulbs, and flowers have a mild onion or garlic flavor, which many people enjoy.
If you didn’t know: According to the University of Tennessee Extension, “Native Americans of the Cherokee nation used wild garlic for medicinal purposes, including as an expectorant and as a treatment for asthma and scurvy. The Rappahannock chewed raw bulbs for high blood pressure and shortness of breath. The Hopi used wild garlic for food.”
How can onion grass damage your lawn?
Onion grass may seem harmless, but its presence in your lawn can spell trouble. Left unchecked, it can take over and transform your picture-perfect lawn into a mess. Here are some ways this broadleaf weed can undermine the health of your grass:
- Competes with your grass for water, sunlight, and nutrients, resulting in stunted growth, thinning, and overall reduced vitality. This weakens the grass and makes it more vulnerable to foot traffic, diseases, and pests.
- Spreads rapidly, forming dense clumps that can overwhelm your grass and dominate the area.
- Interferes with routine lawn maintenance tasks such as mowing and edging. The thin, wiry leaves can become tangled in the mower blades, leading to uneven cuts and damage to your equipment.
- Obviously, onion grass in your lawn takes away from its visual and olfactory appeal. The unattractive leaves and distinct odor can put quite a dent in your ability to maintain a manicured, pristine lawn.
How to eliminate onion grass
To control onion grass, you’ll need to roll up your sleeves, arm yourself with patience, and take a multifaceted approach.
- Identify the weed: To identify onion grass, look for thin, grass-like leaves that give off an onion or garlic aroma when squeezed. If they grow in clumps throughout your lawn, it’s onion grass.
- Dig it up: Grab a shovel or similar tool and dig around the onion grass clumps in your lawn. Push your tool down deep to loosen up the soil.
- Pull out the bulbs: Using your glove-covered hands, pull the hidden bulbs out of the soil and try to get as much of the roots as possible to prevent regrowth.
- Monitor your lawn: Don’t assume that doing this once is enough to get rid of onion grass for good. Like most weeds, onion grass can be sneaky, so keep an eye out for stragglers that might wreak havoc later on. Check your lawn regularly and pull out young weeds before they get the chance to mature.
- Consider using herbicides: If manual removal just isn’t cutting it, you have the option of using a liquid or granular post-emergent herbicide formulated specifically for broadleaf weeds such as onion grass. According to the North Carolina State Extension, “bruising the foliage before the application of post-emergence herbicides can help with uptake.” Stick to the label instructions and avoid non-target plants as much as possible.
- Don’t give up: Persistence is key when it comes to weeds. Getting rid of onion grass will take time and effort, so don’t get discouraged if what you try doesn’t work overnight.
How to prevent onion grass
If onion grass in your lawn keeps you up at night, we provide some strategies for controlling it and restoring your peace of mind.
- Maintain a healthy lawn: This goes without saying, but one of the best ways to prevent weeds is to maintain your lawn in top shape. This means regularly fertilizing, watering, overseeding, and mowing your lawn. You should also aerate your lawn to improve air, water, and nutrient circulation and remove any thatch buildup as needed.
- Test your soil. A soil test can indicate whether your soil is acidic, in which case you’ll need to add amendments to curb onion grass growth. Applying agricultural lime dolomite lime, wood ash, baking soda, or organic matter can neutralize acidity and raise pH levels.
- Nip young onion grass in the bud: Monitoring your lawn goes a long way, and dealing with onion grass is no exception. The sooner you spot weeds in your grass, the easier they are to remove and prevent from reappearing. In the early stages, manual removal can be enough to eradicate onion grass.
- Keep your mower blades sharp: Cutting your grass with sharp blades can prevent onion grass from spreading.
- Know your weeds: Do your research and stay vigilant. It never hurts to know as much as possible about the weeds that grow in your area and how to control them.
- Plant beneficial plants: Groundcovers, shrubs, creeping perennials, and other landscaping can crowd out onion grass and similar weeds. Besides reducing the chances of weed establishment, they boost curb appeal.
- Apply preventative weed killer: If all else fails, pre-emergent herbicides can help you in your fight against onion grass. Weed killers form a barrier in the soil that prevents seeds from developing roots and shoots.
FAQ about onion grass
Is onion grass toxic to pets?
Onion grass isn’t typically harmful to pets, but it’s related to onions and garlic, and a large amount can spell trouble for your furry friend. If you’re currently dealing with onion grass in your lawn, it’s best to err on the side of caution and keep your pet away from the trouble area.
Can I compost onion grass?
Composting onion grass shouldn’t be a problem as long as the bulbs and seeds are thoroughly decomposed to prevent regrowth. Otherwise, the plant will spread as you apply the compost to various parts of your yard.
Does onion grass provide any environmental benefits?
Most homeowners consider onion grass a nuisance, its invasive nature generally outweighing any potential benefits. That said, its flowers have been known to attract pollinators, in particular honey bees.
A professional can keep your lawn thriving
If you’re all about that healthy, lush, manicured lawn, keeping weeds at bay is a must. But if DIY isn’t your thing, a local pro can tackle the problem and offer helpful advice along the way. Staying on top of your lawn care game pays off – whether you do it yourself or call in the pros.
Main Photo Credit: Hüseyin Cahid Doğan / Wikimedia Commons / CC BY-SA 4.0
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