Erysimum make up a large genus of plants that can be hardy annual, hardy biennial, or hardy perennials in nature. They can range from 15 cm to about a metre in size.
They are very similar to true wallflowers hence some of their common names. Some common names for Erysimum include Alpine Wallflower, Coastal Wallflower, Siberian Wallflower and Blister cress.
They have foliage that is lance like and bloom in the spring with yellow or orange four petaled flowers.
Depending on the species they can be used in both rock gardens or in the border.
Some of the latin names of these plants include Erysimum cheiri, Erysimum cheiranthoides, Erysimum linifolium and Erysimum allionii.
Erysimum capitatum - Western Wallflower by Miguel Vieira
Erysimum asperum - Prairie Rocket Wallflower by Photogramma1.
Common Names: Wallflower, Blister Cress. Wallflower: Siberian; Alpine; Western; Diffuse; Wormseed; Smelly; Pallas'; Kotschy; Coastal; Shy; Fairy; San Francisco.
Life Cycle: Hardy annual. Hardy biennial. Hardy perennial.
Height: 4 to 50 inches (10 to 130 cm)
Native: Mediterranean, North and Central America, Europe, Southwestern Asia.
Growing Region: Zones 3 to 9.
Flowers: Late winter, spring.
Flower Details: Yellow, orange, violet. Raceme. Four petals. Bilateral. Fragrant
Foliage: Narrow. Lance.
Sow Outside: 1/4 inch (6mm). Annuals and biennials: spring; perennials: spring or autumn. Spacing 3 to 10 inches (8 to 25 cm). Germination time: two to four weeks.
Sow Inside: No.
Requirements: Full sunlight. Good drainage. Soil pH 5 to 8. Average soil. Deadhead. Autumn mulch in cold areas. Propagate: cuttings in spring.
It depends on the species as to when the Erysimum seeds should be planted out:
1. Annuals: Autumn or spring.
2. Biennials: Start in spring, move in autumn.
3. perennials Spring or Autumn
Seeds should be planted at a depth of about 7 mm into a sunny part of the garden that has good drainage. They usually take about two to four weeks to germinate. Wallflowers and other Erysimum members like a dry soil of pH 5 to 8.
Once growing you should care for Alpine and other wallflowers by deadheading after flowering and giving them a mulching in the Autumn. If you require more plants then cuttings should be took in the spring; as Erysimum plants self seed this may not be necessary.