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Tuesday, April 3, 2018

How to Control Wild Onions – Organically

Wild onions (Allium canadense) is a cousin of the wild garlic. You can taste the garlic if you chew on a leaf. It looks like a small garlic bulb growing and will produce small flowers, just like onion and garlic will do. They not only grow from seeds but also below spread below ground through small bulblets. One way they spread is from birds that eat it (the flowers will have seeds) and spread it in their poop.
Organic Methods of Controlling Wild Onions
Wild onion plants are very difficult to remove and control because of the way they spread. Many gardeners nearly cut off the tops, resulting in more growth! If you only pull out a part of the bulb and leave the root and its many small bulblets behind, it will continue to spread.
I always teach folks the long term and the short terms methods of control.

Here is the long term.

It is all about the soil. Wild Onions, like most plants, will only grow if certain conditions are met. I have observed that this plant will do well in poor soil. Leave the ground alone and never take care of it. Overwater the plants that are growing on it. Never use compost or add trace minerals or always use chemical furthers. These are the conditions Wild onions all grow in. Change that, and you will be on your way to its long-term control. You will also notice that they require a specific ph to grow. Guess what ph your soil is around here if you do not add organic matter, compost, etc.? It will be very high and very alkaline. Lower the ph down to below 7 ph. Best at 6.8 and you will not have Wild Onions growing in it. New that takes time. So it’s long-term. Start by applying rock dust, live compost, and mulch. You may have to break up the current soil. Actually, you will have to do that, so it is covered in the short term. What you want is a living soil with a ph of 6.8-7.0.

Here is the Short term

First off, you all need to remove as much of the Wild Onions as possible. There are several ways to do this.
First off you can start by using a small shovel and disturb break up the soil, being careful around plants. I would actually throw the soil away. Make sure if you do throw it away that you take it to the dump and not just throw it away in a different part of your property otherwise you would have only moved the problem. I would make sure you remove all parts of the plant. I would then water it and wait about a week or two and remove any new growth. Make sure you dig up the area instead of pulling he plant out. Once you are certain there is nothing coming up, I would place a layer of cardboard and then add a mix of compost and clean soil. You can buy both at your local nursery. I would then pat it down and add a thin layer of mulch. This will take a while to settle down.Keep an eye on any onion growth and pull out as soon as you see it. Look around for any growth in other parts of the property as there is probably more around that is causing it to spread and repeat the process. Look at your neighbors and if they also have it either tell them what you are doing or live with the fact that will always be a cause and keep an eye out for any new growth.
You can kill wild onions with either vinegar or boiling water. Both boiling water and the vinegar will kill any plant it touches. So just spray the leaves. The boiling water will have to be done fast before it cools off so they may not be possible so I would buy white vinegar and pour the whole bottle into a gallon of water in a sprayer. Just spray the leaves, and it will die back but not entirely kill the plant. You can soak just that spot, and it should also kill the bulb below, but I would go one step further and simply remove it once you have killed it. To also slow down its spreading, you can always keep it cut low.
Many folks do not mind this wonderful plant. They will grow in many places that most plants will not plus provide flowers forces and other insects.
If you do not need to use the area in the future, say you want a path clear of it, you can simply cover it with something that will last, and the plants will not grow there without sun. I have used old rugs cut into shape to fit the path and then have it covered up with a layer of mulch. You can also just use several layers of cardboard covered with mulch. If you want to use wood chips, you all need to place a layer that will stop their growth. You can use landscape screen. I would not use plastic because the plastic will eventually break apart. I have used a thick layer of newspaper (all are recycled) and of course, covered with mulch or wood chips.
I would probably not use wood chips with all these fires around us these days so use a nice mulch like azalea/gardenia mix which is really soil and therefore will not burn. You can also use pebbles to cover it or even broken glass. That might sound strange, but there are many companies that sell crushed glass in various color. While safe to walk on, I would not walk on it barefooted or let children walk on it so that will be an issue to consider.
Hope this helps.
Check out my new book “Don’t Panic Its Organic.”
Any questions?
andylopez@invisiblegardener.com