Wednesday, May 9, 2012

Organic Weed Control

 Crabapple LandscapExperts have noted the demand for alternatives to toxic chemicals to control weeds is rising. Consider two modes of operation: mechanical and common household chemicals. 

Mechanical Methods Organic Weed Control

Apply mulch before the weeds get started
Organic mulches
Wood chips, pine straw, compost
Layers of newspaper
Temporary area: cover with thick opaque plastic for 3 months

Cover soil with clear plastic (painters plastic) to steam-cook weeds
Smooth and level soil, 
Water thoroughly
Causes heat build-up under plastic, and weeds steam cook

Hand pulling/weeding by hand
Slow and steady wins the race
Remove all seed heads (trash, not compost)
Screw driver
Cobra head
Pronged weeding tools

Scuffle or Oscillating Hoe
Warren Hoe
Flaming or Weed Torch
xNot recommended
xBurns off tops but often roots are still alive
xDangerous, burning permit required, not within 50 feet of structures
xYouTube video where house caught fire
√More economical for large areas
xNeed burning training  
xHave hose and shovels ready

Common Home Chemicals Used for Organic Weed Control

Boiling water
Entirely organic with no lingering effects
Boiling water in kettle or coffee carafe with pour spout
Pour slow stream directly on crown of plant
4 hours later look like cooked vegetables
Wear long pants and closed-toe shoes to avoid burning if spilt
May need to repeat if entire taproot has not been scalded

Acetic acid
Full-strength white table vinegar
Spray in small sprayer
Add a few drops of liquid dish soap as a wetting agent
Quick-acting, Non-selective
Can change pH of soil
Later, weeds may re-grow from roots
Some weeds are not susceptible to vinegar (waxy coating, storage roots)

High salinity causes reverse osmosis
Slow but effective
Affects soil, runoff too
Can reverse by flooding with water several times
“Sow the fields with salt” punishment for defeated cities b/c prevents regrowth of plants. Also a symbolic purification of conquered cities

Rubbing Alcohol
Draws water out of cells
Non-selective and will kill your good plants too

Sodium hypocholorite, breaks down to water and salt
Harsher for environment than vinegar

Corn Gluten Meal
Biproduct of corn patented by Iowa State U in 1991
Pre-emergent Seeds sprout then corn gluten meal inhibits roots from growing and young seeds dehydrate
Narrow window of opportunity: timing just as weed seeds are germinating in early spring
Doubles as 10% Nitrogen organic lawn fertilizer

Common Recipe for Organic Weed-Killing Mixture
1 Quart vinegar
1 Cup salt
Few drops liquid dish soap
Hand sprayer
Spray foliage, works best in sun


  1. Great recipe for the vinegar/salt mixture. Make sure you only hit the weeds, though. That stuff will kill anything!

  2. That's for sure, D. Aldridge! it is non-selective.