Organic Weed Control

 

Vinegar Weed Killer Overview:

The best option that I have found for organic weed control is spraying vinegar on the leaves.  It’s rather surprising how well vinegar weed spray works and it is quite cheap.

 

How vinegar works:

• When sprayed on the leaf surface, the acetic acid in the vinegar disrupts the leaf’s ability to regulate evaporation.
• As a result, a leaf covered in acetic acid will quickly dehydrate and wilt.
• As you might imagine, this effect is most dramatic on a hot day.

 

Making it work better:

• Some plants have a waxy covering on the leaf surface.  And as a result, water (and vinegar) will roll off the leaf.
• This will cause the vinegar to be less effective or non-effective.
• If you add something else to your vinegar mix, such as soap, it will negate the effectiveness of the waxy leaf surface.  A soapy mix should more evenly cover the leaf surface without beading-up and rolling off.

 

Anything else?

• Nope that’s it -pretty simple.  Nothing else is needed in the spray mix.
• Some people have advocated adding table salt to the spray mix.  However, I believe this is totally unnecessary.  In addition, salt has a tendency to stick around and build up in the soil.  Most plants hate salty soil.  Therefore, using salt in your spray can have negative long term consequences with no apparent benefit.

 

Type of vinegar:

• There are many different concentrations of vinegar.
• The higher the acidity percentage printed on the bottle, the more acetic acid is in the fluid.
• Several sources indicate that you need at least 10% vinegar to work on weeds.  However, these higher concentrations are hard to find in your local grocery store.  I have found that the more common concentration of 5% vinegar works pretty well, although a higher concentration would be better.

 

Personal safety:

• Although vinegar is commonly used in many different types of food, (pickles, salad dressing, etc), some people many have an adverse reaction to it.
• This is especially true with the higher acid concentrations of vinegar.
• Even low concentrations of acetic acid may burn some people’s skin and the vapors may be irritating to the lungs.
• Be cautious.  Gloves and a mask may be prudent for some people.

 

Collateral damage:

• The acetic acid in vinegar is non discriminatory.  It can damage the leaves of any plant it touches.
• Therefore, be mindful of spraying on a windy day and keep clear of your beloved plants.
• Covering adjacent plants with a bucket or upside down pot while you spray may help to protect them from unintended collateral damage.

 

What you will need:

• Garden Sprayer:
  • I recommend that you get (and label) a separate spray bottle for the vinegar.  You don’t want to expose your plants to vinegar residue left in a spray bottle when you later spray your plants for something else.
• Vinegar:
  • There are several concentrations of vinegar available.  Almost every grocery store has 5% vinegar on the shelf.  However, I have not found the stronger, more effective >10% vinegar in any of our local grocery stores.  However, stronger concentration vinegar is available on amazon.com
    .
• Liquid soap:
  • Simple liquid soap is the best.  There is no need to get the antibacterial type of liquid soap.  In fact, I would think that the antibacterial effects would have a negative impact on your soil and the added chemicals would not do anything to kill the weeds.

 

My simple technique:

1. Pour 1 gallon of vinegar in a spray bottle.
2. Add about 3 tablespoons of simple dish washing soap or liquid hand soap.
3. Shake bottle.

 

My results:

See pictures below.

 

Misc:

• For best results spray on a dry hot day.
• Rain will wash off the spray.
• The process is not systemic. It only affects the leaves.  However, by damaging the leaves the rest of the plant is severely weakened and often dies.
• A repeat application the next day usually finishes off any stragglers.  This may be necessary if you use the lower concentrations of vinegar.