Pitcher's Thistle

Swamp Thistle should be watered regularly with a deep soaking once per week to a depth of several inches. During the hot summer months, the plant may need more frequent watering and may benefit from a shallow layer of mulch to help retain soil moisture. From September to mid-July, the plant can survive with its natural rainfall or a once a week deep irrigation. Be sure to allow the soil to dry out between waterings.

Swamp Thistle needs full sunlight more than 4-6 hours of strong, direct sunlight per day to thrive in a range of habitats, including moist soils in wet meadows, bogs, marshes, shorelines, and ditches. It grows best in consistently moist soil, but will tolerate short periods of inundation and longer droughts. Good growth and flowering generally occur from April to September.

Swamp Thistle (Cirsium muticum) should be pruned in late-spring or early-summer, after the plant has flowered and set seed. The extent of the pruning will depend on the desired size and shape of the plant, but generally you should trim back the stems moderately, removing any dead or diseased stems and cutting those that have become too long and/or crowded. It is also important to reduce the overall canopy size of the plant by removing any excessively long branches. Pruning should be done with sharp, sterile pruning shears to reduce the risk of introducing disease.