Garden Vinegar Weed Killer (When Mulch Fails)

Gardening naturally has its challenges. Some times more than others. Like when your tired-and-true method of for garden bed weed prevention (mulching), completely fails.   Then it’s time to experiment—this time with garden vinegar weed killer.  

Spraying with Garden Vinegar Weed Killer – Note Protective Gear (Ignore Ugly Baggy Shirt)

But first the problem–and a little backstory…  

We have a shade garden that we’ve kept (mostly) weed free for years—simply using mulch.  Four layers of newspaper (no glossy ads), overlapping at the edges, topped with wood chips.  All carefully spread around a large planting of perennials. Repeat every 2-3 years.  Easy peasy (other than the year we mulch).

But enter a new house, with a new garden bed.  We applied our standard newspaper and mulch solution but within weeks some strange variety of (really sharp) grass was poking through.  Then the dandelions, etc. followed.  

The BEFORE picture

We mulched again with a thicker layer of newspaper and a bigger overlap.  The weeds came back again.

I still can’t explain this.

My (half-serious) theory is the grass is part of some kind of large interconnected organism with roots connected to related grasses all over the world.  They send food and moral support (“bore through that newspaper; you can do it”).  Did anyone see the Borg on Star Trek?     

So, I decided to try household vinegar (5%) mixed with citrus oil.  Failed.  Roundup (shhh).  Failed. Then I gave up and let the weeds thrive for a few years.  I figured corporate Mom’s don’t have perfect gardens.

Then I quit my job—oops, no more excuse. 

So finally, I discovered 20% garden vinegar weed killer. It’s kind of like your salad vinegar gone rogue (as in 4 times as strong and poisonous).  The theory is that it dries out the weeds.  

24 hours later

And. It. Worked.

Really!

Here is what we do:  

• Wait for a day that is warm and sunny (this is Wisconsin, so I can tell you 70’s will do). But this is important.
• Apply 20% garden vinegar weed killer with a sprayer using appropriate protective gear—eyewear, gloves, completely covering skin (look at my picture above)—this is a serious acid.  Read all the cautions on the bottle.  Avoid the plants you want to keep (you are unlikely to kill a bush, but you will maim it—I hand pull the grasses that retreat into my roses).
• Wait 24 hours.
• Hand pull any aggressive grasses, even if they appear dead, to get as much as possible of the (really long) root system which is not completely dead.  They don’t fight as much as before they were sprayed…
• Mulch the bed with a 4 sheet thick layer of newspaper and top with wood chips or other organic mulch.
• If grass pokes through (in smaller quantities this time), hand pull going for as much root as possible and adjust mulch.
• If broadleaf weeds return, re-spray (or hand pull for small amounts). 
  

  Hand pull grasses inside plants (wearing gloves for roses 😉 )

Now people may be concerned about harm to the environment, but from what I’ve read (great info here), the acetic acid breaks down quickly so is unlikely to create any long-term toxicity. The biggest issue will be if your plants are really close together since avoiding the “keepers” will be a challenge.  On the other hand, sidewalk cracks are a cinch!

There is one other barrier to experimenting with this–you may have to order it off the internet and shipping isn’t cheap.  I bought a single one gallon jug my first year trial and a four pack the second year (which we are still using in year 3).  

Our garden sprayer

My final advice is to get a good sprayer.  You don’t want anything that dribbles since you don’t want this on your skin.  I would also avoid any sprayer that requires a strong squeeze action unless your area is quite small (my hand got tired).  The one in the picture (which is on its third year), is pumped to create pressure and then let’s you apply a mist for a few minutes after which you pump again. 

And of course, pay attention to all the safety precautions. This stuff is strong and will discolor concrete if left on it. Don’t even think about getting it on your skin ir eyes (note safety goggles).

But for the first time EVER, the neighbors came over to tell us how good our yard looked! 

Year 3 of (mostly) weed free beds!

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