Killing Wild Onions – Tips For Getting Rid Of Wild Onion Plants
By: Heather Rhoades
Wild onions (Allium canadense) can be found in many gardens and lawns, and wherever they are found, a frustrated gardener is sure to be found nearby. These difficult to control weeds are the bane of many gardens, but with determination and a little hard work, you can get rid of wild onions once and for all.
Identification of Wild Onion Plants
Wild onion weeds grow in clumps and are typically found in flower beds or near difficult to mow areas, though they can also grow in the lawn. Wild onions can be identified by their thin, waxy, spear-like leaves. Wild onion is often confused with its close cousin, wild garlic. Wild onions have flat leaves while wild garlic has round leaves.
Wild onions grow from white bulbs. They will either spread by forming bulblets on their bulbs, creating larger clumps, or by seed, spreading the wild onion plants to other parts of the garden.
Wild onions are edible but only if they have not been treated with a chemical herbicide.
Methods to Get Rid of Wild Onions
Wild onion plants are difficult to control for two reasons.
- First, because they grow from bulbs and bulblets, which break apart from each other easily, so it is difficult to remove an entire clump without leaving some roots behind.
- Second, the thin waxy leaves make it difficult for herbicides to stick to the leaves and, even if it does, the wax makes it difficult for the herbicide to penetrate into the wild onion plant.
If ever there was a plant made to survive weed removal methods, wild onion weed is it.
For these reasons, wild onion control needs to be a done with a combination of methods. It is best to take steps to get rid of wild onions in the spring, before the plants have a chance to go to seed, or in the fall, which will weaken any surviving wild onion plants, making it more difficult for them to survive through the winter.
Killing wild onions starts with removing as much of the clump of wild onions as possible. Do not try to pull the clump of wild onions out of the ground. The small bulblets are designed to pull away from the mother plant when pulled, which leaves extra bulbs in the ground that will rapidly regrow. Instead, dig the clump out of the ground with a spade or a trowel. Throw the entire clump away. Do not try to shake excess dirt off back into the hole and do not compost. If you do this will only re-spread the wild onion bulblets back into your garden.
The next step to kill wild onions is to treat the area with either a non-selective herbicide (as a last resort) or boiling water. Both boiling water and non-selective herbicide will kill any plant it touches, so keep this in mind in regards to surrounding plants.
After removing the wild onion plants, keep a close eye on the area and repeat the process if any new wild onions start to grow. Due to the hardy, break-away bulblets, you can expect that they will grow back at least one time.
If you are unable to treat the area or are keeping the wild onion plants as an edible, keep the plants trimmed (higher for growing as an edible and near the ground if unable to treat as described). This will prevent the wild onion from spreading to other parts of your yard through seeds.
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The 'Bulbing' Weeds: Wild Onion, Wild Garlic and Star of Bethlehem
Q. Dear Mike: I'm from the Philadelphia area and LOVE your show (and my maiden name is McGrath, which, I confess, is why I started listening). Anyway, we moved south, and our home's lawn is plagued by wild garlic. My 14-month-old daughter will be playing on this grass so no herbicides. What can we do instead? Thanks,
- ----Emily in Knoxville, TN
- ---Rosemary in Philadelphia
- ---Lori in Kankakee (Illinois)
The answer to these weeds in flower beds and high-quality lawns is intelligent pulling. I'm mystified that Lori in Kankakee says that they're "impossible to pull", as I have had some of the distinctive clumps appear in my peach orchard and the entire clump comes out easily when I pull on it gently but firmly after a good, soaking rain. This is one of the many benefits of improving your soil, boys and girls—weeds that sprout out of nice, loose rich soil that contains a lot of organic matter in the form of compost practically pull themselves out. Conversely, weeds that grow in lousy, compacted clay are pretty firmly anchored.
And pulling from wet soil is always more productive than dry. So go out after a rain, reach down to the soil line and tug gently that's how you get the underground bulb out completely. If you only snap them off at the soil line, the plant is not harmed you spend the same amount of time and energy as someone who does it correctly, but get no benefit.
You can also remove tight clumps with a sharp, long-handled 'poachers spade', which is also a very useful tool for transplanting and rabbit hunting in Merry Old England.
Single sprouts are the most annoying and time-consuming to deal with. So be smart. If you have a large area with mostly single plants, clear small sections at a time, being sure to pull slowly and get the bulbs completely out. Start with highly visible areas and give yourself several seasons to do it all if you've just been cursing them for the past five years, you can't expect overnight eradication. And don't let the un-pulled plants in other areas set seed while you're doing this mow or weed-whack the tops off those miscreants before they can procreate.
In a lawn, the best answer is always the indirect approach grow a healthier lawn. That means using a corn gluten meal weed and feed in the Spring to provide a nice feeding and prevent any dropped seed from sprouting and then provide a big natural feeding with compost or a bagged organic lawn fertilizer in the fall for cool-season grasses like bluegrass and fescue. No summer feeding for cool-season grasses! And no chemical fertilizer—ever!
In addition, never cut cool-season lawns lower than three inches. Water all grasses deeply and INfrequently, and only when needed never water every day, for short periods of time, or on a schedule that ignores rainfall. Do these things and the alliums—and other weeds—will diminish naturally over time
And I would be remiss if I did not note that these plants are edible, and highly sought after as ingredients in Springtime 'tonics'. Yes, the flavor IS very sharp compared to that of cultivated alliums, but that's a sign that they contain much higher amounts of allicin and other natural antibiotics and cancer-fighting compounds than their cultivated cousins. Try mixing small, well-chopped-up amounts into dishes. Or chop some up (cloves and greens) and soak them for a few months in a good quality apple cider vinegar to make delicious garlic vinegar.
Q: Dear Mike, I'm being plagued by the beautiful six-petaled flower, Star of Bethlehem, and want to know how I may eliminate it.
- ---Harry in Levittown, PA
- ----Linda in Collingswood, NJ
Or install edging to keep it confined to certain areas and consider this entry from Anna Pavord's excellent and highly recommended new book "Bulb" (Mitchell Beazley 2009): "If you have not been brainwashed to think of it as a thug, Star-of-Bethlehem will appear unexpectedly charming, with wide spreading heads of light, feathery, airy flowers with very precise habits, opening at 11 o'clock and closing at three in the afternoon. A good flower to naturalize in meadow grass or under shrubs."
Pulling: With a small number of weeds, pulling, though difficult, is an option. It is easier to pull up large groups of bulbs when the soil is moist. However, it’s likely that bulbs or bulblets will be left in the ground and new leaves will later re-emerge. For best results, dig them out with a thin trowel.
Mowing: Mowing will not kill wild garlic or wild onions. However, regular mowing can weaken plants and prevent them from setting seed.
Chemical: Unfortunately, there are no preemergence herbicides that will control wild onion or wild garlic. They must be treated with a postemergence herbicide, and persistence is the key. Plants will need to be sprayed more than once and for more than one season. One characteristic that makes control difficult is that both have a thin, glossy leaf to which herbicides don’t readily adhere. Unlike most weeds, mowing wild garlic or wild onion immediately before applying an herbicide may improve uptake. After application, do not mow for at least two weeks.
Timing of Sprays: Treat wild garlic and wild onion in November and again in late winter or early spring (February or early March) before these plants can produce the next generation of bulbs. However, be careful not to apply most weed killers onto centipedegrass or St. Augustinegrass during their spring green up period. Inspect the lawn again in the spring and the next fall, and treat if necessary.
Recommended Herbicides: Imazaquin, the active ingredient in Image Nutsedge Killer, will provide control for wild garlic and wild onion. This product should not be used on fescue and should not be applied to warm season turf during green up in spring. Wait at least 1-½ months after treatment before reseeding, winter overseeding or plugging lawns. This product is not for use on newly planted lawns, nor on winter over-seeded lawns with annual ryegrass.
Three-way broadleaf herbicides containing 2,4-D, dicamba, and mecoprop (MCPP) will provide control of wild garlic and wild onion with repeat applications. Examples of three-way herbicides for residential lawns in homeowner sizes are:
- Ferti-lome Weed-Out Lawn Weed Killer – Contains Trimec® Concentrate
- Southern Ag Lawn Weed Killer with Trimec ® Concentrate
- Bayer Advanced Southern Weed Killer for Lawns Concentrate + RTS
- Spectracide Weed Stop for Lawns Concentrate + RTS
- Bonide Weed Beater – Lawn Weed Killer Concentrate
- Ortho Weed B Gon Weed Killer for Lawns Concentrate + RTS
These products can be used safely on most turfgrasses, but reduced rates are recommended when applying to St. Augustinegrass or centipedegrass. Apply during November, very early spring, and again the next November for best control. Do not apply these herbicides during the spring green up of warm season turfgrasses, or over the root zone of nearby ornamental trees and shrubs. Do not apply these products to newly seeded grasses until well established (after the third mowing). Treated areas may be reseeded three to four weeks after application. Always check the product label for rate of application and to determine that it is safe for use on your species of turfgrass.
Celsius WG Herbicide, which contains thiencarbazone, iodosulfuron, and dicamba, will control wild garlic, especially if applied when the average daily temperatures are over 60° F. Apply in the fall and again 2 to 4 weeks later. The addition of a non-ionic surfactant, such as Southern Ag Surfactant for Herbicides, will increase control. Celsius is selective to control many broadleaf weeds & several grass weeds in all four of the common warm season turfgrasses, but cannot be used on a fescue lawn.
Imazaquin, as in Image Kills Nutsedge Concentrate or RTS, maybe used on warm season lawns for wild garlic and wild onion control. Do not apply to warm season turfgrass during the spring green-up of the lawn. It is not for use on fescue lawns & do not apply to St. Augustine lawns during the winter.
For Landscape professionals Metsulfuron, such as in Quali-Pro MSM 2500 Herbicide and Manor Herbicide give very good control of wild garlic & wild onions in bermuda, centipede, St. Augustine, and zoysia lawns. Quali-Pro Fahrenheit Herbicide also contains metsulfuron along with dicamba. For these three professional products, a non-ionic surfactant, such as Southern Ag Surfactant for Herbicides or Hi-Yield Spreader Sticker Non-ionic Surfactant, is required at 2 teaspoons per gallon of spray mix for best control. A non-ionic surfactant will help the herbicide adhere to the leaves for increased penetration, but many temporarily cause yellowing of the turfgrass. Blindside herbicide also contains metsulfuron along with sulfentrazone. Apply metsulfuron products to lawn at least one year old and when temperatures are below 85 °F.
Do not apply metsulfuron to a lawn if over-seeded with annual ryegrass or over-seed for 8 weeks after application. Do not plant woody ornamentals in treated areas for one year after application of metsulfuron. Do not apply metsulfuron herbicides within two times the width of the drip line of desirable hardwood trees.
Glyphosate is a nonselective herbicide that will also provide control of wild garlic and wild onion. If you are unable to prevent glyphosate from getting on desired actively growing grasses, a selective herbicide should be used. To avoid harming the turfgrass, apply glyphosate during winter, but only to bermudagrass once the lawn is completely dormant. However, during mild winters, the turfgrass may not be completely dormant. Examples of glyphosate products in homeowner sizes are:
- Roundup Original Concentrate,
- Roundup Pro Herbicide,
- Martin’s Eraser Systemic Weed & Grass Killer,
- Quick Kill Grass & Weed Killer,
- Bonide Kleenup Weed & Grass Killer 41% Super Concentrate,
- Hi-Yield Super Concentrate,
- Maxide Super Concentrate 41% Weed & Grass Killer,
- Super Concentrate Killzall Weed & Grass Killer,
- Tiger Brand Quick Kill Concentrate,
- Ultra Kill Weed & Grass Killer Concentrate,
- Gordon’s Groundwork Concentrate 50% Super Weed & Grass Killer,
- Zep Enforcer Weed Defeat III,
- Eliminator Weed & Grass Killer Super Concentrate,
- Monterey Remuda Full Strength 41% Glyphosate,
- Knock Out Weed & Grass Killer Super Concentrate,
- Southern States Grass & Weed Killer Concentrate II,
- Total Kill Pro Weed & Grass Killer Herbicide,
- Ace Concentrate Weed & Grass Killer.
If this document didn’t answer your questions, please contact HGIC at [email protected] or 1-888-656-9988.
Chuck Burgess, Former HGIC Horticulture Extension Agent, Clemson University
Joey Williamson, PhD, HGIC Horticulture Extension Agent, Clemson University
This information is supplied with the understanding that no discrimination is intended and no endorsement of brand names or registered trademarks by the Clemson University Cooperative Extension Service is implied, nor is any discrimination intended by the exclusion of products or manufacturers not named. All recommendations are for South Carolina conditions and may not apply to other areas. Use pesticides only according to the directions on the label. All recommendations for pesticide use are for South Carolina only and were legal at the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies. Follow all directions, precautions and restrictions that are listed.
Fix-It Chick: How to eradicate wild onions from your yard
The best way to remove wild onions for good is to dig them up.
If your lawn is filled with tufts of bright-green, waxy, smelly foliage, it may be time to get out the shovel and start digging. Wild onions are invasive plants, spreading year to year both from seed and bulb. A multi-tiered plan of action is the best way to eradicate wild onions.
Step 1: Address the issue in the early spring and again in the fall. Wild onions (and wild garlic) are perennial plants that grow through the winter and produce flowers, bulblets and seeds in the early spring. Plant foliage dies back in the summer, leaving bulbs lurking beneath the ground awaiting cooler weather to sprout again.
Step 2: A single wild onion plant can produce dozens of seeds. Mowing down or cutting back onions before they bloom will eliminate their spread by seed, but will not stop their reproduction of underground bulbs.
Step 3: Chemicals such as 2,4-D and glyphosate can be somewhat effective, but they tend to roll off the waxy leaves of the plants. Instead of spraying, brush the chemical directly onto freshly cut foliage.
Step 4: Digging plants out completely is by far the best way to eradicate wild onions. The bulb set beneath the ground is typically larger than the footprint of foliage above the ground. Water the area thoroughly and begin digging several inches away from the plant with a small shovel. Dig beneath the initial bulb set to capture as much of the plant and surrounding soil as possible.
Step 5: If possible, kill any remaining bulbs by pouring boiling water into the newly dug hole. Boiling water will kill any plant it comes in contact with. Poured directly onto existing foliage, boiling water will kill the apparent plant, but may not eliminate all of the bulbs beneath the soil.
Step 6: Bulbs and seeds added to a compost pile will flourish. Dispose of plants, bulbs and soil in the trash rather than the compost bin.
Step 7: Weeds tell us a lot about soil conditions. Wild onions prefer alkaline soils with fewer nutrients. Test the soil to see if adding lime may solve the problem. Spreading compost to increase the nutrient value of the lawn will also help reduce the onion population.
Step 8: Consider borrowing a pig to root out wild onion and garlic bulbs. The pig will destroy the lawn, but at least the onions will be gone!
Wild Onion / Wild Garlic: Kill, Control & Prevent It
Wild Onion and Wild Garlic are easily recognized from the garlic or onion odor of their crushed leaves. Some people confuse wild onion with a chive plant, an herb that looks very similar and also has an onion odor.
Wild garlic (Allium vineale) and wild onion (Allium canadense) are winter perennials, with wild garlic being predominant in North Carolina. They emerge in late fall from underground bulbs and grow through the winter and spring. In late spring, aerial bulblets are formed and the plants die back in early summer. The underground bulbs can persist in the soil for several years. While both have thin, green, waxy leaves, those of wild garlic are round and hollow, while those of wild onion are flat and solid.
Wild onion and wild garlic are very common lawn weeds. Fortunately, there are easy solutions for controlling them. With a small number of weeds, pulling, though difficult, is an option. It’s likely, however, that bulbs or bulblets will be left in the ground and new leaves will later re-emerge. For best results, dig them out with a thin trowel.
Unfortunately, there are no preemergence herbicides that will control wild onion or wild garlic. They must be treated with a postemergence herbicide, and persistence is the key. Plants will need to be sprayed more than once and for more than one season. One characteristic that makes control difficult is that both have a thin, glossy leaf to which herbicides don’t readily adhere. Unlike most weeds, mowing wild garlic or wild onion immediately before applying an herbicide may improve uptake. After application, do not mow for at least two weeks.
Treat wild garlic and wild onion in November and again in late winter or early spring before these plants can produce the next generation of bulbs in March. However, be careful not to apply most weed killers onto Centipedegrass or St. Augustinegrass during their spring green up period. Inspect the lawn again in the spring and the next fall, and treat if necessary.
Recommended herbicides includeImazaquin, the active ingredient in Image Nutsedge Killer, and will provide control for wild garlic and wild onion. This product should not be used on fescue and should not be applied to warm season turf during green up in spring. Wait at least 1-½ months after treatment before reseeding, winter overseeding or plugging lawns. This product is not for use on newly planted lawns, nor on winter over-seeded lawns with annual ryegrass.
Three-way broadleaf herbicides containing 2,4-D, dicamba and mecoprop (MCPP) will provide control of wild garlic and wild onion with repeat applications. Examples of these products are Bayer Advanced Southern Weed Killer for Lawns, Spectracide Weed Stop for Lawns – for Southern Lawns, Lilly Miller Lawn Weed Killer, Southern Ag Lawn Weed Killer with Trimec®, and Ferti-lome Weed-Out Lawn Weed Killer. These products can be used safely on most turfgrasses, but reduced rates are recommended when applying to St. Augustinegrass or centipedegrass. Apply during November, very early spring, and again the next November for best control. Do not apply these herbicides during the spring green up of warm season turfgrasses, or over the root zone of nearby ornamental trees and shrubs. Do not apply these products to newly seeded grasses until well established (after the third mowing). Treated areas may be reseeded three to four weeks after application. Always check the product label for rate of application and to determine that it is safe for use on your species of turfgrass.
Glyphosate, the nonselective herbicide found in Roundup Original, Eraser Systemic Weed & Grass Killer, Quick Kill Grass & Weed Killer, Bonide Kleenup Grass & Weed Killer, Hi-Yield Super Concentrate Killzall Weed & Grass, Maxide Super Concentrate 41% Weed & Grass Killer, and Southern States Grass & Weed Killer Concentrate, will also provide control of wild garlic and wild onion. If you only have them in a couple different areas in the lawn, spot treat them with Ortho® Weed-B-Gon® MAX® Weed Killer for Lawns Ready-to-Use. If you are unable to prevent glyphosate from getting on desired, actively-growing grasses, a selective herbicide should be used. To avoid harming turfgrass, apply glyphosate only to warm- season grasses in winter, when they are completely dormant.
Around trees and shrubs and in flowerbeds, spot-treat with Roundup® Ready-to-Use Weed & Grass Killer Plus. Shield surrounding foliage and desirable plants when using this product and avoid applying it in windy conditions.
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North Carolina Cooperative Extension, Lee County Center.
Post authored by Susan Condlin. Minda Daughtry is the current agent for your contact.