Posted on behalf of UW student and UWBG volunteer intern, Mitch Halliday.
Mitch volunteered at the Arboretum this past quarter as one of our “Greenhouse and Vegetable Garden Caretakers”. The endless task of weeding the garden beds obviously had an impact.
Vinegar Weed Killer:
Vinegar contains a weak acid, Acetic acid. By applying this vinegar to the soil, it lowers the pH, increasing the acidity, of the soil from a range that is tolerable to an intolerable level. Most vinegars have an acid content of around 5%, a more concentrated solution of 10% to 20% will more effectively kill weeds. This is not however a miracle solution, at the right strength this organic weed killer will kill the leaves of any plant it comes in contact with, but not the roots. Which makes this treatment most effective on young weeds which do not have enough energy stored in their roots to successfully regrow. Repeated applications will be needed to permanently disable more established weeds.
Vinegar Weed Killer Recipe
• 120 mls (4 ounces) Lemon juice concentrate
• 1 liter (1 quart) white or cider vinegar
Spray bottle for applying organic weed killer Simply mix the two ingredients together in a spray bottle and you have your organic weed killer formula.
Spot spray it directly on the weeds, being careful not to spray desirable plants. For the most effective result the best time to spray is during the heat of the day.
Weed Killer #2
- 1 tbsp gin
- 1 tbsp cider vinegar
- 1 tsp dish detergent
- 1 quart water
Mix all ingredients in a large bowl and pour into a spray bottle. This method will kill the roots, but will prevent growth afterwards for 3-5 days, so it should be used in an area that you do not intend to plant in.
- Weeding, we all know how tedious and back-breaking it can be, but it is the most effective natural method of controlling weeds. To make things easier on yourself weed after it has rained or wet the ground around weeds to make them easier to pull out. An investment into a few weeding tools will go a long way as well.
- Pour boiling water on weeds. Making pasta or boiling potatoes for dinner? Instead of pouring that hot water down the drain, pour the water your weeds and they will shrivel and die in a few days.
- Blackout. All plants need sunlight to survive, weeds are no different. By layering newspaper or scrap paper (it’s biodegradable) over the weeds and blocking out the sunlight they will die.
- Eat ‘em. Many of the weeds present in our gardens are in fact edible. Dandelion leaves, for example are excellent in a tossed salad. I would suggest picking up a book about wild-forage from a library or book store.
- The hardest of all, Learn to love them. Maybe it’s time to appreciate these little plants for their natural beauty, hardiness, and pervasiveness.
 “Organic Weed Killer Formula: Natural Homemade Vinegar Weed Killer Recipe..” Sustainable Living on a Small Farm the Permaculture Way. Web. 6 June 2012. <http://www.small-farm-permaculture-and-sustainable -living.com/organic_weed_killer_formula.html>.
 Richford, Nannette. “DIY: How to Make Organic Weed Killer.” Yahoo Voices. Web. 6 June 2012. <voices.yahoo.com/diy-organic-weed-killer-1393951.html>.
 Yeager, Jeff. “Homemade Organic Weed Killers.” The Daily Green. Web. 6 June 2012. <http://www.thedailygreen.com/green-homes/latest/homemade-weed-killers#fbIndex1>.