Bishop's weed is the common name for the plant Aegopodium podograria, an herbaceous perennial in the Apiaceae, or carrot, family; it is native to Europe and Asia. In the Middle Ages, bishop's weed was cultivated and harvested for use as food and medicine. Medicinally, it was used to treat gout, which led to the alternate common name goutweed. Other common names are ground elder and snow on the mountain. As a garden plant, bishop’s weed is used as a ground cover, though it should be planted with caution, because this plant can be highly invasive.
Bishop’s weed spreads from rhizomes that grow laterally, creating a dense patch that is effective in shading out other low-growing plants. The aggressive nature of bishop’s weed provides a hardy solution as a ground cover in areas with difficult growing conditions. The plant grows from 2 feet to 3 feet (about 0.6 m to 1 m) tall with a thick, dark green canopy. One popular cultivar, called variegatum, has blue-green leaves with white edges. Bishop’s weed is often used as a border along shrubs and flowerbeds, as an edging along paths, or as a ground cover under trees.
The white flowers are small and bloom in a clump at the end of a 3-foot (about 1 meter) stalk. The flowers grow in a flat-topped cluster, a formation called a compound umbel, which is common in the carrot family. The flowers bloom in abundance in late spring and early summer, covering the ground with white, snowy flowers.
Bishop’s weed prefers full shade and damp soil, though this hardy plant can withstand a range of growing conditions. Full sun, partial shade and rocky, poor soil are all within the range of acceptable habitats. It thrives in both slightly acidic and slightly alkaline soil in a pH range of 6.1 to 7.8.
When planting bishop’s weed as a ground cover or border, plants should be spaced about 18 inches (45 cm) apart. As the rhizomes spread, the canopy grows together, forming a thick mass of dense foliage. Division of the rhizome is the fastest and easiest method of propagation. The rhizomes can be divided any time of year, though spring is the ideal time. The plant is dug out of the ground and divided into multiple clumps, each having an eye where a new plant will emerge; the divisions should be replanted immediately, either in the ground or in pots filled with potting soil.