As gardeners, we like to think we work with nature, and that is true to some extent. Despite attempted cooperation, nature is hedging its bets on our garden plots. Just in case we don’t fill our plots with plants, nature has a horde of plant seeds (we call them weeds) waiting to come in and grow. Unfortunately, nature just assumes we will fail and those seeds promptly germinate to take over without asking how we feel about it. How rude.
So, to keep our gardens happy, we get out there and pull most of the weeds. When there are too many, we may get out the weed torch (be careful!) or our sprayer and apply some sort of herbicide (read the label!). Whatever your stance is on the use of garden chemicals, I hope you use them as an absolute last resort. But don’t worry, I’m not writing today about the general pros and cons of herbicides. Partly because I have a different but related topic in mind, but mostly because I don’t want a torch and pitchfork-wielding mob at my doorstep.
Instead, I want to discuss the use of vinegar and salt/Epsomsalt asaweedkiller in our gardens, sidewalks, and driveways. But before I do, let’s briefly mention an important safety note. Be on the lookout for Giant Hogweed and Poison Hemlock, two outright dangerous weeds. Please go look them up on the Kitsap County Noxious Weed Program website (extension.wsu.edu/kitsap/nrs/noxious) right now. Both species are contact andingestionpoison hazards. Touching or tasting them can potentially cause you great harm. You absolutely do not want them growing in your yard, especially if you have children or pets. Don’t bother spraying them. Don’t even touch them. Instead, contact the Kitsap County Noxious Weed Program (WSU extension) for advice. You can report an infestation via their website.
So if your weeds don’t include Giant Hogweed and Poison Hemlock, vinegar might be an option for you. Vinegar from the grocery store mixed with salt has become popular over the last several years as a homemade weed killer. Before you go mix up a tank,however, there are some things you should consider first. It may help or not be worth the trouble depending on your situation.
The vinegar and salt mix is a contact weed killer, meaning that it only kills the part of the plants that it touches. Contrary to some myths that I’ve read, a foliar spray absolutely does not kill roots. Most weeds sprout back from the roots within a few short weeks of being sprayed with vinegar. Repeated sprays may keep the weeds in check and some of them will peter out and die eventually. But, beware. Repeated sprays with vinegar and salt are problematic.
Vinegar alone can kill weeds under the right circ*mstances, and adding salt significantly improves its efficacy, but salt is adouble-edgedsword here. Applying the salt and vinegar mix repeatedly can lead to a plant-unfriendlybuild-upof salt in the soil. The term “salting the earth” came in part from the practice of applying salt onsoilto prevent plants from growing, and frequent use of salt and vinegar weed killer can lead to similar results.
If you insist on repeated use, give strong consideration to giving your garden a good deep watering occasionally to flush the salt through. If you are using regular table salt in your mix, sufficient watering and occasional deep watering should help alleviate salt build up. “Should” is the operative word here. Don’t go nuts with your salt and vinegar weed killer.
Some recipes call for regular table salt. Many call for Epsomsalt. Both will work and abuild-upof both in your garden soil is bad. Too much of any salt can lead to wilting and dead plants, and while using Epsomsalts avoids table salt’s potential for sodium toxicity, excess magnesium from Epsomsalts can interfere with phosphorus absorption in plants (that’s bad). Epsom salts provide the plant nutrients magnesium and sulfur but, like any fertilizer, overuse can be detrimental toyourplants.
The popular vinegar and salt weed killer can be a useful tool in our control of weeds, but it is not a cure-all. Be careful where and when you apply it. Like any medicine, too much is not good. Incorporate other methods of weed control. Go ahead and pay the neighbor kid five cents for every weed pulled. Just check to make sure they get the roots with the tops.
Darren spends much of his time talking to weeds in the moss garden at the Bloedel Reserve. When not busy promising them he will never spray them with vinegar and salt, he can be reached atpnwbotany@gmail.com.
