Weeds are one of the biggest complaints among gardeners, second only to pests and the weather. For the organic gardener, you may think that weeds are simply the negatives that you have to accept with the positive benefits of organic principles. But that’s not the case! There are a number of organic methods you can employ to control and even prevent unwanted weeds.
Whenever possible it is always best to stop weeds from even sprouting in the first place. Here are a few of the best preventive tactics.
Install Landscape Fabric
When installing new beds or hardscape areas such as patios and walkways, first install a layer of high quality landscape fabric. Landscape fabric is a special material that lets water through and allows the soil to breathe, but suppress weeds from growing from underneath. When using in flower beds you will need to cut holes in the fabric to allow garden plant roots to penetrate the soil. I tend to use the fabric mostly in hardscaped read for this reason.
Minimize Bare Soil
Weeds are opportunists looking for any bare spots in the soil to fill. So the first path to weed control is not giving them any ground to stand on—literally!
In flower beds, you can minimize bare soil in one of two ways.
- Apply a thick layer of mulch: A thick layer of wood mulch, usually 2-3” thick, will prevent weeds as well as maintain steady temperatures and retain more moisture in the ground.
- Use Ground Covers: You can also use ground covers to fill in bare spots between plants. There are numerous ornamental and edibles plants that work as ground covers. For ornamentals, go-to’s include asiatic jasmine, silver pony foot, creeping juniper, and periwinkle. Edibles and their ornamental counterparts include many varieties of oregano and thyme, some of which are variegated and flower. Horseherb also makes a great ground cover, even though many people consider it a weed. Its actually a beneficial native and very hardy.
In turf areas, minimize bare soil by encouraging healthy turf. This is done by:
- Using the right kind of turf for the site: Use try right kind of turf not only for your region, but for the conditions of the site including sun exposure, soil, and water availability.
- Improve soil: Health soil that is full of organic matter and porous promotes stronger roots, and therefore stronger plants. Aerate in the spring and fall and top dress with compost to promote healthy turf.
- Water deeply and infrequently: Water turf deeply 1-2 times a week, or to supplement rainfall to ensure at least 1” of water is applied weekly. By watering deeply and less often, you encourage deeper roots, which promote stronger plant. Watering shallow and more often creates shallow root systems that dry out easily and create a weaker plant that is susceptible to disease and pests.
- Mow Higher: Most folks cut their grass too short. This stresses the turf, allows it to dry out, invites pathogens, damages the crown, and most of all creates space for weeds to invade. Different turf grasses have different recommended mowing heights, so be sure to follow the guidelines for your species of turf.
Water Low and Slow
Another method for controlling weeds is watering your plants with either underground drip or with bubblers, soaker hoses, or other irrigation methods that apply water as close to ground level as possible. By applying at ground level at the plants root system, you avoid providing water to weed seeds sitting in the soil’s surface.
Use Corn Gluten as a Pre-emergent
The discovery of corn gluten’s use as a pre-emergent herbicide was a happy accident. While testing it for other uses, it was discovered that corn gluten stops a number of weeds seeds from germinating, including many of the annoying grass seeds that we often find invading our gardens. To effectively use corn gluten, first it must be applied before weed seeds germinate. This means applying late summer/early fall (July through September) to prevent cool season weeds and again in winter/early spring (January through March) to prevent warm season weeds.
It generally takes a few years of regular applications to reach maximum effectiveness. It’s also recommended to apply it at a rate of a minimum of 20 lbs per 1,000 s/f, though it can be applied at a rate of up to 80lbs/ per 1,000 s/f without causing any damage. Corn gluten is activated with moisture, so without a rain event it will need to be watered. However, extended rain or water exposure can reduce its effectiveness.
Getting Rid of Existing Weeds
If you already have weeds, you have a few options.
Honestly the best way to get rid of weeds is to pull them. Not only is it great exercises, but pulling up weeds, roots and all, ensures you’ve eradicated the whole plant and eliminated any chance that it can come back. You especially want to pull weeds before they flower and go to seed, so you can prevent any babies from coming up later on.
Scalding hot water will kill most things, including weeds. This works in hardscape areas and bare soil areas. The challenge is transporting the hot water, not splattering and scalding yourself, and not getting it into contact with other plants. P.S. this works on ant hills as well, but it takes a giant pot of boiling water.
Vinegar that is 7 percent or higher in concentration can kill weeds, though it often takes multiple applications. In large amounts vinegar can also impact the pH of your soil. I personally haven’t had much luck with vinegar since it does take so many applications.
Citrus, clove, and garlic oil have been utilized as effective herbicides. However, they are non-selective, meaning they will damage any plant they come into contact with, weed or not. There are many ready to use applications available or you can buy concentrated versions and dilute them for use.
In most cases, you will need to use a combination of strategies to eradicate and control weeds moving forward. Prevention is always best, so focus on creating a healthy ecosystem and using sound cultural practices to grow strong plants and avoid weeds in the first place.