Cow parsnip is a plant of impressive dimensions, sending up a flowering stem 4 to 15 feet tall in its second year from a basal rosette established in its first. It is the sole North American native in the genus Heracleum and occupies the wet margins of the continent: streambanks, marsh edges, and damp open meadows. In North Carolina it is found in the western mountains, where it is part of the native flora rather than a garden intruder. The broad, 6 to 8 inch compound umbels of small white flowers attract an exceptional diversity of pollinators, making it genuinely valuable in naturalized areas and rain gardens where scale is not a concern.

It grows best in silty or sandy loam in full sun to partial shade, though it will manage in other soils as long as consistent moisture is available. It is a biennial or short-lived perennial, so allowing some seed set is the practical way to maintain a colony. Its visual relationship to giant hogweed (Heracleum mantegazzianum) causes confusion, but cow parsnip is considerably smaller and is native. Even so, the sap of this species can cause mild skin sensitivity in some individuals, so gloves are reasonable when handling it. In a large naturalistic garden, planted at the water's edge, it is quietly spectacular.