If you have wild garlic or wild onions growing in your lawn or flower beds, you know how unattractive these weeds can be. If either is growing in your lawn, you also know how offensive they can be to your sense of smell.
But if you’re unfamiliar with either of these common weeds, it’s difficult to imagine why they could be such a problem.
Wild garlic and wild onions are both very invasive and they reproduce themselves prolifically. Both plants reproduce from underground bulbs and also from seeds that are set from their blossoms.
One wild garlic or wild onion plant, if allowed to blossom, will produce dozens of seeds that can grow into many more plants to infest your lawn.
Wild garlic (Allium vineale) and wild onions (Allium canadense) are related to the domestic varieties of garlic and onions that we grow in our gardens and use in the kitchen.
The problem with these wild cousins however, is that they refuse to stay in their place. Instead, they grow and spread wherever they want to grow, especially in soil that is acidic.
Both of these wild alliums are considered to be winter perennials. Wild garlic and wild onions emerge early in the fall while many other plants are preparing to go dormant for the winter.
They continue to grow throughout the winter and into the spring. In the spring, these plants produce their blossoms which then form tiny bulblets - their seeds - on the tips of the long, narrow leaves.
After the blossoms and bulblets have formed, the plants die back in early summer. But lurking beneath the surface of the soil, the bulbs patiently wait for cooler weather when they will once again send up their leaves. The bulbs and bulblets can both remain in the soil for several years, waiting for the right conditions for sprouting.
Unlike so many other weeds that can be controlled by chopping, pulling or spraying, wild garlic and wild onions present a different challenge. Mowing the foliage or pulling it from the garden will not affect the bulbs beneath the soil, and within just a few days the bulbs will simply send up new leaves.
Mulching over them does not discourage either plant. Both will easily push through several inches of mulch and they will even grow right through weed-barrier fabric. Wild garlic and wild onions also tend to grow much faster than lawn grass, so within a couple days of mowing, the wild allium will already be growing in unsightly clumps that are taller than the surrounding lawn.
Not only that, but while the lawn is being mowed, the wild garlic or onions will give off a strong, distinct odor of onions that will linger for several hours.
Another characteristic of wild onions and wild garlic that makes them difficult to control is the design of their leaves and the waxy coating that covers them.
Both plants have thin leaves that easily shed herbicides, and the waxy coating helps prevent absorption of the herbicide. Wild garlic has round, hollow leaves while the leaves of wild onion are flat and solid, but both are proficient at shedding an application of herbicide.
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But now that you understand the enemy, you will be better prepared for battle against this smelly pest. If you have only a few clumps of either wild onions or wild garlic in your flowerbeds or lawn, the best solution is to dig them out.
Do not try to just remove the bulbs by pulling them up by their leaves. The bulbs can grow as much as six inches beneath the soil surface and they can be very difficult or impossible to pull out.
Grab a shovel and dig them out. The bulbs will be in a clump, and not all of them will have sprouted. Remove the entire clump of bulbs along with the soil that surrounds them. Some bulblets can be very tiny and difficult to see, so it is best to discard the surrounding soil along with the bulbs.
Do not add the bulbs to your compost pile. If the compost is not hot enough to thoroughly cook the bulbs, they can remain dormant for a long time, then come back to haunt you once the compost is spread on the garden. This is one instance where it is preferable to discard the whole mess in the trash.
Digging out the bulbs would be a daunting task if wild onions or wild garlic has infested a large portion of the lawn. If either of these pests are taking over your lawn and it smells like onion soup when you mow, changing the pH of your lawn is a simple method of discouraging wild alliums.
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Both wild onions and wild garlic prefer to grow in acidic soils that are low in organic matter. Appling lime and compost to the soil will increase the organic matter and change the pH to levels that are inhospitable to wild alliums. Be careful to not apply lime near acid-loving plants such as rhododendrons or azaleas.
If you are not opposed to using chemical herbicides, look for a post-emergent herbicide that can be applied to the wild garlic or wild onions. Do not use a preemergent herbicide as this will have no effect on the underground bulbs.
Before applying an herbicide to the wild alliums, it is helpful to mow the plants to rough up their foliage and increase their ability to absorb the herbicide. Once the herbicide has been applied, do not mow again for at least two weeks.
The best time to treat a wild onion or wild garlic infestation with herbicides is in November, with a second application in late winter or very early spring before the plant begins producing more bulbs in March.
Be careful to apply the herbicide only to the garlic or onion plants, as it can also kill nearby plants. A small paintbrush or sponge is helpful for applying herbicide only to the targeted plant.
Herbicides containing 2-4-D, dicamba, glyphosate or mecoprop are most effective on wild garlic and wild onions. If you are unsure about which brand to use, ask for help at your local garden center, and whenever using herbicides or other lawn chemicals, always carefully follow the instructions for the product you buy.
There is one more solution that will get rid of wild garlic or wild onions in your yard. Even though it is highly effective, this solution can damage the lawn so much that it would need to be replaced, and this solution would not be feasible in every neighborhood.
The first step of this solution would be to build a strong fence around the infested area. The second step would be to bring in a pig – yes, a pig – to root out the garlic or onion bulbs.
Pigs seem to love both wild garlic and wild chives and they will root out and eat all of the bulbs. But pigs aren’t adept at covering their tracks, so it would then be up to you to renovate the uprooted lawn. Personally, I’d rather try changing the lawn’s pH.