Organic Control of Weeds

Safe, Natural Practices for Controlling Weeds

Lawn
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Organic gardening and lawn-care practices nurture plants and control diseases and pests in ways that are natural, avoiding methods that call for synthetic chemicals and unnatural manipulation. 

Organic weed control is much more than killing weeds safely. It is first about growing healthy plants or lawn turf in fertile soil to minimize weed pressure. Organic weed control is further achieved by using an Integrated Pest Management (IPM) program that seeks to establish a weed threshold that is an acceptable price to pay for a safer, non-chemical garden and lawn.

Under IPM standards, eradication of weeds by chemical means is a last resort.  

For the organic gardener, there is no quick fix, magic spray weed killer for lawns or gardens.  Organic weed control is more about the holistic organic management of the lawn and garden, which in turn results in fewer weeds. The theory (and practice) being that a healthy lawn, garden and soil will promote vigorous plant growth that will out-compete weeds., 

The first step of organic weed control is to test the soil to learn its needs. Naturally amending and fertilizing the soil according to the soil test is the first step of any organic weed control program.

Organic Weed Control in Lawns

In a lawn, even more so than in a garden, correct cultural practices must be performed to reduce the opportunity for weeds to thrive. Weeds thrive on weak, stressed turf and compacted, unhealthy soil. Eliminate those conditions and turf grasses will win over weeds.

Here are some tips for fostering good lawn grasses organically: 

  • Mow at the highest level possible to encourage a dense lush, lawn capable crowding out of weeds.
  • Reduce compaction by aerating. Most experts recommend aerating once each year, in the faull. 
  • Improve water and nutrient uptake by de-thatching--when it is necessary. De-thatching is an aggressive action that can damage grass plants. It is necessary only when thatch has become so dense that it prevents water and nutrients from penetrating into the soil. 
  • Topdress the lawn with compost. This is a simple matter of spreading a light layer or organic and well-decomposed compost onto the lawn and raking it in. 
  • Re-seed bare patches in the fall, well before frost. This will help thse areas from being taken over by weeds in the spring.
  • Avoid scalping the lawn when mowing. Damaged grass crowns recover very slow and give weeds an opportunity to establish.
  • Water deeply and infrequently. Maintain adequate soil moisture but do not over-water. Many weeds have superficial roots and are fostered if waterings are frequent. 

Organic Methods for Controlling Weeds in the Garden and Lawn

If the need for eradicating weeds is still present, a multitude of organic methods is available.

  • Corn gluten meal is an organic pre-emergent herbicide that also fertilizes. Like its synthetic chemical counterparts, it suppresses seed germination and provides a quick green-up for a lawn. 
  • Acetic acid in vinegar has plant-killing properties and can be used as a non-selective weed killer. Household vinegar contains no more than 5% acetic acid and needs to be repeated applied to kill weeds. Stronger concentrations are available as organic commercial weed killers. Remember, non-selective means that it kills all plants, so handle with care.
  • Herbicidal soaps are natural products for controlling mosses and algae, and there are numerous weed-killing formulations using natural oils, concentrates and other organic substances. These are all non-selective herbicides; there are no organic (selective) herbicides yet available that kill only broadleaf weeds without affecting turf grasses and garden plants. 
  • Mechanically remove weeds with manufactured weed puller tools, long screwdrivers, hand trowels or bare hands. A variety of "weed-popper" tools make this work easy and offer the added benefit of providing lawn aeration. In a garden, systematic weed pulling will gradually result in a garden that is easy to care for, since weeds are no longer present to go to seed. 
  • Weed flamers are gaining popularity as an organic weed control. They are essentially modified propane torches used to burn problem weeds.