Snake grass (Equisetum hyemale) goes by many common names, including joint grass and mare's tail. Its segmented, cane-like foliage and dense growth habit add striking visual interest to water gardens and container plantings, while its low-maintenance care needs make it ideal for out-of-the-way areas of the garden. Snake grass is not without drawbacks, however. It is highly invasive and poisonous to horses and cattle, so it must be grown under controlled conditions away from livestock.
Snake grass adapts easily to most climates and will perform well within U.S. Department of Agriculture plant hardiness zones 3 to 11. Young, tender growth may die back with heavy frost, but it will return in the spring after the soil and air have warmed. Snake grass spreads aggressively in most climates, but is especially problematic in warmer areas where its growth is constant year-round.
Because of its highly invasive nature, snake grass should only be grown in pots. Choose a 12- to 18-inch pot with no drainage holes and fill it with a potting mix of half loam or compost and half coarse sand. A mildly acid soil pH between 5.6 and 6.5 is best, although snake grass will adapt to neutral soil without issue. Space plants 3 to 6 inches apart for a thick, lush appearance. Snake grass takes on a weedy, thin appearance under heavy shade, so choose a spot with three to five hours of direct sunlight each day to keep foliage healthy. As moisture-loving plants, snake grass will grow in standing water up to 6 inches deep, but the plants will also perform well when grown on dry land. When positioning the pot, make sure the lip is above the surface of the soil or water to keep the plant from escaping.
Snake grass needs constant access to moisture year-round to maintain its health and attractive appearance. Growing snake grass in cachepots or other nondraining containers decreases the need for frequent watering because the moisture doesn't drain off, so it is best to water by touch rather than relying on a strict schedule. Water whenever the soil mixture feels barely damp just beneath the surface, adding water until the top 3 inches are saturated. During hot or windy weather, check the moisture level in the soil more often and water, as needed, to keep it moist.
The nutrient needs of snake grass are minimal. Plants require no supplemental fertilizer, relying solely on the nutrient content of their soil to support their growth. Snake grass does benefit, however, from yearly repotting to refresh its soil. Repot snake grass on a concrete or other impermeable surface rather than on a grassy surface where its root fragments might fall and take hold. Keep the same size pot to discourage spreading, but fill it with a fresh potting mixture of half compost or loam and half sand. Most snake grass plants also benefit from annual division to reduce their size. Cut the root ball into two or three equal-sized pieces and pot each in its own container.