The Erysimum is a genus from the mustard or cabbage family (Cruciferae or Brassicaceae) and is native to Europe. The Erysimum is also known under the synonym Cheiranthus and is commonly named wallflower because this plant can grow out of walls. The wallflower is available in many colours.
Erysimum is an annual, a biennial or perennial. The perennials are short lived and do not look very nice at the end.
The wallflowers that are sold as perennial are fairly hardy, but wet winters can be fatal. By cutting back the perennial in mid-summer you can prevent it from becoming too woody and leggy. Because the perennial is a short lived plant (about 3 years), it is best to save some cuttings to be able to replace the old plant. The flowers of many species are sterile which means that they will not produce seeds. Cut off a shoot of approximately 7 centimeters (3 inches) long. Cut off flowers and buds and cut away all but three leaves. Dip the shoot into a rooting hormone and plant it in a pot of compost. Erysimum linifolium ‘Bowles’s Mauve’ is an example of a short lived perennial. It flowers for a long time (April – October) and has purple, non-fragrant flowers.
Most wallflowers are sold as annual or biennial. These have the best scented flowers, but they do not flower as long as the perennials. The Erysimum cheiri is an example of such a biennial plant. They have fragrant flowers in many colours.
You can sow the biennial Erysimum in summer. You can do that directly where you want them to grow in your garden or in little pots first. You can plant the seedlings in autumn in their final flowering position. They will bloom in April – May the next year. Biennial varieties will self-seed.
If you sow the Erysimum cheiri indoors (preferably at 15 - 18 ºC (59 - 64 ºF)) at the end of March. It will then grow as annual and will bloom in July – August. At the end of April (after the frost period) the seedlings can be planted in the garden.
The easiest option is to buy a flowering plant in spring and plant that where you want it. That way you know for sure that you have the color you want.
Wallflowers prefer a warm, sunny spot with rich, chalky and well-drained soil, but they are not particularly fussy about soil. Wallflowers are often used in rock gardens and are salt and drought tolerant. In the warm summer regions the Erysimum cheiri likes some protection against the afternoon sun.
The flowers are a good source of nectar for many insects and hummingbirds and make good cut flowers.
Attracts bees: yes
Deer resistant: yes
Exposure: sun/ part shade
Flower color: various
Flowering time: April – June
Foliage color: green
Fragrant flower: yes
Hardiness: -10 ºC (14 ºF)
Height: 16 inches (40 cm)