Imagine baby’s breath (Gypsophila spp) on steroids; that’s colewort. The oversize foliage and towering inflorescence evoke a fun feeling of the tropics for gardeners in colder, drier climes. Colewort, also referred to as giant crambe, is a plant having enough physical existence in the backyard to serve as a focal point and also anchor a varied planting strategy.
Jocelyn H. Chilvers
Jocelyn H. Chilvers
Botanical name: Crambe cordifolia
Common names: Colewort, giant crambe
Where it will grow: Hardy to -20 levels (USDA climate zones 5 to 8; locate your zone); does not tolerate hot, humid climates
Elevation range: Up to 7,000 feet
Water necessity: Moderate
Light requirement: Total sun
Mature size: 4 to 7 feet tall and 4 to 5 feet wide
Benefits: Colewort supplies that piece of supersize fun every garden needs and produces a solid contrast to more finely textured plants.
Seasonal curiosity: Flowers June to July; showy foliage spring to fall
When to plant: Spring to fall
Jocelyn H. Chilvers
Distinguishing attributes. The large foliage clump — with leaves around ten inches long — resembles that of rhubarb. Countless small white flowers form a dense, cloud-like inflorescence on sturdy stalks around 7 feet tall.
Jocelyn H. Chilvers
How to utilize it. Colewort functions best as a single accent specimen in the backyard, instead of scattered here and there.
Use it using classic June bloomers like peony (Paeonia spp), Oriental poppy (Papaver oriental), iris (Iris spp) and roses (Rosa spp). Plants using silvery-blue or grey foliage — like Powis Castle blossom (Artemisia), blue oat grass (Helictotrichon sempervirens) and rose campion (Lychnis coronaria) — are amazing companions, too.
Jocelyn H. Chilvers
Planting notes. Colewort prefers full sun but will tolerate partial shade. Moderate average and water, well-drained garden dirt are perfect. Although colewort has a bulky, imposing root system, I’ve been successful transplanting it in early spring, just as the leaves begin to emerge.