Delphinium cardinale aka Scarlet Larkspur

Delphinium cardinale has two common names: cardinal larkspur and scarlet larkspur. It belongs to the buttercup family, Ranunculaceae. This herbaceous perennial lives for years but has no woody stems. Its native range spans southern California and northern Baja California. It grows there on dry slopes in chaparral. Kew puts it in a subtropical climate region. It is not native to Britain or Ireland. The species name refers to its red flowers.

The flower stems stand upright above the basal leaves. These deeply split leaves grow at the plant's base. They can die back before the flowers open. Thus, stems in bloom may have few leaves in view. The flower racemes can reach 6 feet [1.83 metres] tall. Racemes bear flowers along a main stem. The listed garden spread is about 2 feet [0.61 metres]. This tall, slim shape gives blooms height without much width. The leaves and blooms need not peak at once.

Bright red flowers bloom from May to July. This runs from late spring to the middle of summer. Each bloom measures about 0.08 feet [0.025 metres] across. The flowers grow along upright racemes, not single, low stems. Their red hue gives the plant its main garden show. The blooms draw hummingbirds, so they suit bird gardens. They add colour to native plantings and rock gardens, too.

Grow cardinal larkspur in soil that drains well. It suits rocky or sandy ground, even shallow, stony sites. It accepts soil ranging from evenly moist to dry. Full sun suits it near the coast. Some shade works, too. In hot, dry inland gardens, give it afternoon shade. Its need for water shifts with the seasons. It needs a dry summer rest. Cut back extra water while it lies dormant. Missouri Botanical Garden lists USDA hardiness zones 7–10.

This plant adds tall blooms to naturalised plantings. It also suits gardens for native plants and birds. It can cope with dry soil and shallow, rocky ground. This gives it more uses where soil depth limits plant choice. Missouri Botanical Garden rates its care needs as low. It also lists the plant as deer resistant. Good drainage and a dry dormant phase are key care needs. The loss of leaves with the seasons forms part of its growth cycle.