So how do you know if that plant you are looking at in the ground is really a weed? Pull it up. If it comes out easily, it wasn’t a weed! Although that’s not really the true definition, it seems to be the case, more often than not. So just what is a weed anyway? The most widely accepted definition is simply “a plant out of place”.
I get many questions about how to control weeds in lawns and gardens organically and selectively. Honestly, that presents a challenge, but with a little patience and dedication satisfactory results are achievable.
First, the best defense is a good offense. Take lawns for example. Beyond manual methods, such as hand pulling, once weeds are present, organic controls are unavailable to selectively eliminate only the weeds. Promoting the health and vigor of the lawn is also the best way to starve off, shade out and out compete the weeds too.
But when you’re ready to manage weeds with organic controls, there are several options. The following is a listing of some of the most popular methods using eco-friendly options.
Hand-pulling or manual extraction has an element of satisfaction that no other weed control method can offer. If you like instant gratification, manual extraction is the only way to go. It’s also one of the few ways for selective control.
Although highly satisfying, I realize it’s not always a practical solution to the problem. Time and ambition are usually the two most important assets to taking on a manual project. However, hand weeding in any size garden is easiest after a soaking rain. The soil is soft and roots easily yield to even the gentlest tug.
But be aware of one caveat. Tap rooted weeds must be pulled out in their entirety, making sure to get the entire root! Otherwise, any remaining piece will provide sufficient energy for that weed to regenerate a new plant.
One of the most effective organic weed control techniques available and certainly one of the most environmentally friendly, is to provide natural barriers to weed formation. A layer of mulch two to four inches thick is a very effective means of preventing most weeds from germinating.
I’ve used just about every type of mulch barrier available, including traditional bark and straw mulch, plastic sheeting and wet newspapers with additional mulch on top of that.
Here’s one caveat; if you want to know that the bagged mulch you buy is free of potentially harmful contaminates, such as arsenic from treated wood, be sure each bag has the certification seal of the Mulch and Soil Council. For more information, go to www.mulchandsoilcouncil.org.
Sprays and Drenches
These methods affect plants on contact by burning or desiccating the cell structure of the plant.
Boiling Water works well at killing most weeds with one application. Some weeds, especially those with tap roots such as dandelions may need multiple applications.
Acetic Acid (vinegar) works but common household vinegar at 5% concentration is not effective for mature weeds. Minimum concentrations above 7% are needed to manage tougher weeds and multiple applications may be necessary with tap-rooted weeds such as thistle. Use caution when using acetic acid as it can burn skin and eyes on contact. Approved sources for herbicide use can be found online or at farm supply stores.
Plant-based ingredients such as citric oil, clove oil, and garlic are non-selective post-emergent herbicides also. Use caution as they will injure or kill all vegetation they come in contact with. Tougher weeds usually require multiple applications for complete control. Ready to use products are available through organic gardening supply sources online and in some garden centers.
Corn Gluten is a granular corn-based product that is most commonly used as an organic pre-emergent control in lawns. Although effective, this product takes several seasons to exhibit results as comparable to synthetic options. Corn gluten also has the added benefit of containing about 10% nitrogen by volume for natural fertilization as well. This product is becoming more popular but is not yet widely available in retail garden centers.
Flame Weeders are those devices that use the intense heat of a concentrated flame to destroy the cell structure of the plant. Typically powered by a propane canister, these devices are portable and effective. Simply pass the flame over the weed for several seconds. It is not necessary to visibly burn or ignite the weed. A few seconds of intense heat is all that is necessary.
Like the other methods listed above, because the roots are unaffected, the toughest weeds may require multiple applications. Use extreme caution when working with this tool.
No matter which methods of weed control you prefer, prevention is still the best way to make sure you keep the weeds from spreading next year. Although they can still come into your yard through other means, eliminating weeds on your property before they go to seed will save you many hours of work next year and beyond.