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The Perennial PostPersistence, persistence, persistenceby Irene Mills Q: Is there a way to get rid of horsetails or am I stuck with them forever? A: Yes, you can get rid of them, but it will take persistence. Horsetails (Equisetum spp.) are the surviving remnants of a genus that once included species the size of trees. They are living fossils that have been around since the Carboniferous period (359 to 299 million years ago), so they know a thing or two about surviving in tough conditions. Like their relatives, the ferns, horsetails are primitive vascular plants that reproduce by means of spores; they also spread via creeping rhizomes with roots that can grow to a depth of six feet. (Mary Robson told a Master Gardener class that there is only one horsetail plant in the U.S.—and its roots go from coast to coast). The key to getting rid of horsetails is to understand their life cycle and how they've adapted to changing conditions. In the April 2004 issue of Gardens West, Carol Hall wrote: "Horsetails … thrive in conditions that mimic those that existed millions of years ago — acidic soil (low pH), low oxygen (minute air pockets), and very low nutrients. Moist or boggy soil provides all three conditions, but in many cases dry soil is also acidic, compacted and lean." She goes on to say that changing the soil conditions to raise the pH and promote fertility and drainage gives horsetails "an evolutionary signal that their time is over and it's time for other kinds of plants to take their place." (The entire article is available online thanks to Swansons Nursery in Seattle—see Links below.) What doesn't work Pulling and digging horsetail is counter-productive—it enthusiastically resprouts from the scars left by pulling, or from any tiny bit of root left in the soil. (Having said that, however, I should add that I spotted a feather of horsetail at the edge of my garden this summer and got the whole thing out—I think—by digging up a wide, deep rootball and transferring it to an upturned garbage can lid. I delicately prodded through the soil to examine the roots, which appeared to be intact, and put the horsetail plant in a plastic bag to throw in the regular garbage. The other day my husband asked me why the shovel was leaning on the fence, and I told him it's to remind me to check that spot to see if any more horsetail is coming up. Vigilance!) Trying to smother horsetail with black plastic or a thick layer of bark is also counter-productive. Remember, it thrives in moist, airless, infertile conditions. Some university extension websites recommend application of certain herbicides to control or eradicate horsetail. The catch is, it takes repeated applications of some pretty toxic stuff at specific intervals, and even then there's no guarantee of success. A better answer is to fix the conditions that encourage horsetail in the first place. What does work In early spring, around April, keep an eye out for the fertile, spore-bearing stalks that emerge before the vegetative growth appears. Fertile stalks look a lot like asparagus spears poking up out of the soil, and they are loaded with a gazillion fine spores. When you see these, carefully cut them off, enclose the cuttings in a plastic bag, and put them in the garbage. Photosynthesizing vascular plants can be gradually starved out by mowing or cutting them back to the ground, removing their food factories (the leaves and green parts). Marianne Binetti once wrote about keeping a pair of shears in a plastic bag near a horsetail patch she was trying to eradicate; every time she saw green growth poking up, she cut it off and disposed of the cuttings. It takes time and persistence, but it does work. (You can get rid of ivy and blackberries the same way.) Improve the tilth of the soil by fixing poor drainage, adding organic matter, and raising the pH and fertility:
And finally, since Nature abhors a vacuum and will fill it with whatever is available, you need to implement a no-bare-earth policy: Install landscape plants and ground covers that will out compete horsetails (and other weeds) by depriving them of space, light, and moisture. It can take two to five years of diligent effort to eradicate horsetail. If that seems like a long time, well, remember we're talking about a plant that's been around for more than three hundred million years. Relatively speaking, then, you can get rid of them in less than a blink of an eye. Links: Umass Soil Testing Brochure: Soil Texture Analysis by Ted Sammis: http://weather.nmsu.edu/teaching_Material/soil456/soiltexture/soiltext.htm
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