Horsetail horror

Image: Carolyn Herriot

Here’s my story as to how our weed-free garden acquired the horsetail nightmare. We planted a front hedge in 1974. In year 2000, the empty lots across the street had homes being constructed. The municipality needed access to a water or electrical line. A backhoe lifted one of our huge hedge trees. It was returned and the municipality added some of their topsoil. You guessed it – the topsoil was filled with weed seeds and horsetail! I could use your expertise on this subject.

Conway Lum, Plant problem and pest expert

Horsetail (Equisetum species), much like many other tenacious weeds, spreads mainly via underground roots. The big problem is that, even if there is little or no above-ground portion, the plant will continue to regenerate itself.

However, if you continually “top” the plants, the roots will eventually exhaust themselves, especially in the case of these perennial weeds. This may not happen quickly, and can take as long as two or more years before the problem is under control. As long as the weed is not spreading from outside your property (meaning that it’s isolated in one area), you will eventually prevail.

Control:

1. Weed tops can be hand-pulled or dug out carefully. Do not try to run a rototiller through a bed or you will compound the spread of weed roots. If the roots have
intermingled with desired vegetation (such as perennials, shrubs, etc.), you will have to be very meticulous. Try to dig out the plants; you’ll want to clean out the roots and get at the weed’s root system.

2. Propane-powered infrared burners can be used to scorch weed tops. This is especially effective for large landscaped areas. Stubborn perennial weeds may require three treatments before the root systems weaken.

3. Mulching with either landscape fabric (geotextile) or natural materials (bark mulch, etc.) can be effective. If you are using natural materials without landscape fabric underneath, you will need anywhere from 10 to 15 centimetres of material to keep out the weeds.

4. The use of chemicals is possible, but must be approached with caution. There is a potential inherent risk of chemical damage to existing desirable vegetation, either through drifts or residue left in the soil.