Monkshood 50 Seeds - Aconitum - SHADE PERENNIAL Monkshood Aconitum carmichaelii. A cottage garden classic, long-lived and long flowering from late summer to autumn. The pyramidal spikes of hooded blooms in royal blue are produced in abundance above the attractive, lobed foliage. Prefers a moist, well-drained soil in cool, moist shade. Flowers late summer to autumn. Height: 4-6 feet. Hardy in zones 3-7.