A Gardening Journal
Today in the Garden of a Lifetime: Blue-leaved Cow Parsnip in Bud
- Published: May 28 2016
Each eighteen inches broad and three feet from stem to tip, the titanic leaves of this blue species of cow parsnip could scarcely be more striking. But when this rare monocarp finally does thrust itself into flower, even this foliage is now backdrop.
A foot across, the massive crowning umbel is the mother ship. A few dozen tiny buds crowd together into each of the small clusters, known as umbellets; each is at the tip of its own stalk arising from the umbel's center.
At the base of the umbel's stalk, three ruffled bud scales—each the size of a major lettuce leaf—have opened out fully to reveal a trio of stems that bear the upper rank of secondary umbels.
Each secondary umbel is a week or so behind and, so, still looks like a little head of cauliflower.
Each lower leaf also bears a secondary umbel.
Soon, flowers of the main umbel will open and then mature to seeds, followed shortly by flowers of the secondary umbels. As is the norm for this genus, the single spectacular flower display is followed swiftly by death; the species endures only by seed. In ideal conditions—full sun and loose, well-draining soil—blue-leaved cow parsnip can self-seed prolifically. My rich soil and crowded beds make self-seeding less certain, so I'll collect seeds and sow them in patches throughout the garden in hopes of successful germination.
I'll post again when this plant's primary and secondary umbels are both fully formed.
This blue-leaved species of cow parsnip, Heracleum antasiaticum, can take several years to mature. Here's a look at this plant last year, which was its third season of displaying foliage alone.
Here's how to grow Heracleum lanatum, which is the rare perennial species in this genus of plants that are monocarpic, meaning that they usually flower just once before dying. Its foliage is huge as well, but in the more usual mid-green, and with cow parsnip's typical jagged edges. It matures to slightly larger than H. antasiaticum: four to five feet high and wide. Its hardiness, culture, and handling are similar.
Here's how to grow the giant of the genus, the biennial Heracleum sosnowskyi. Its hardiness, culture, and handling are similar. It can be two to five times the size of H. lanatum, and needs careful siting and handling to keep in control: As with nearly-as-large Heracleum mantegazzianum, all parts of H. sosnowskyi can cause a severe contact dermatitis. Plus, both are self-seeders, and can proliferate into a dangerous infestation if allowed to escape from the garden.