Horsetail is one of the most difficult weeds to get rid of, so no longer having horsetail in your yard is condemnable.

Horsetail spreads by several different methods. Although it does not flower, it does produce spores which are carried through the wind. Horsetail also has an aggressive root system, which consists of rhizomes and tubers, that can spread 2-3 feet wide and 6 feet down into the soil. The combination of spores and rhizomes will make it difficult to keep horsetail from encroaching from your neighbor’s yard.

Horsetail likes to grow in moist conditions and a groundcover of gravel or any type of mulch, which helps to retain moisture, will only help to encourage the formation of horsetail. Make sure the soil is well-draining by adding organic matter or compost.

Since your area is free of horsetail, covering the area with landscape fabric can help prevent spores in the soil from growing through the fabric. It will not prevent the rhizomes from growing and sprouting up around the edge fabric.

Horsetail is less likely to establish in shade. You might want to think about plants to make the area shady. Closely spaced shrubs and trees will not allow as much direct light to penetrate and help to decrease the likelihood of horsetail.

Research shows that making the soil less acidic by adding lime may help to decrease horsetail from reappearing.

A combination of well-draining soil, shade, and lime can help to prevent another infestation of horsetail. Be sure to continually survey your yard and make sure to take care of any horsetail that might have sprouted.

For more information on horsetail:

OSU - Department of Horticulture - Field Horsetail

Horsetail - Scouring Rush

U of W Botanic Gardens - Horsetail