Organic weed control is much more than killing weeds safely. It is first about growing healthy turf in fertile soil and minimizing weed pressure. Organic weed control is further achieved by using an Integrated Pest Management (IPM) program to establish weed thresholds, prevent weeds, and eradicate as a last resort.
There is no quick fix, magic spray weed killer in organic lawn care. Organic weed control is more about the holistic organic management of the lawn and soil, which results in fewer weeds. The theory (and practice) being that a healthy lawn and soil will promote turf growth which will out-compete weeds.
The first step of organic weed control is to test the soil to learn it's needs. Naturally amending and fertilizing the soil according to the soil test begins any organic weed control program.
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 grass will win over weeds.
- Mow at the highest level possible to encourage a dense lush, lawn capable crowding out of weeds.
- Reduce compaction by aerating.
- Improve water and nutrient uptake by de-thatching,
- Topdress with compost.
- Re-seed bare patches in the fall to avoid them from being taken over by weeds in the spring.
- Avoid scalping the lawn when mowing. Damaged crowns recover very slow and give weeds an opportunity to establish.
- Water deeply and infrequently, maintain adequate soil moisture but do not over-water.
If the need for eradicating weeds is still present, a multitude of organic methods are available.
- Corn gluten meal is an organic pre-emergent herbicide with fertilizer. Like it's chemical counterpart, it suppresses seed germination and provides a quick green up.
- Acetic acid in vinegar has plant killing properties and can be used as a non-selective weed killer. Household vinegar does not get above 5% acetic acid and weeds would need repeated applications. Stronger concentrations are available as weed killers. Remember, non-selective means 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. They are all non-selective herbicides and as of yet, there are no organic broadleaf (selective) herbicides available.
- Mechanically remove weeds with manufactured weed puller tools, long screwdrivers, hand trowels, or bare hands.
- Weed flamers are gaining popularity as an organic weed control. They are basically modified propane torches used to burn problem weeds.