Wallflowers (Erysimum linifolium) are easy to care for. You can plant them virtually anywhere and all but forget them. Once they come up, they'll bloom in yellow, red, orange and purple. In fact, they'll bloom until they exhaust themselves. Wallflowers are perennials in the wild, but in the home garden, the flowers often last only for a season or two before they need to be replanted.
Water the wallflowers with 2.5 cm (1 inch) of water weekly if there's no rain. To estimate how much water that is, place a rain gauge (or graduated cylinder) in the wallflower bed when you water. Always use a gentle spray of water focused on the base, not the top of the plants.
Pinch back the tips of long and lanky wallflower stalks to 6.5 mm (1/4 inch) above the nearest leaf node in early spring just before new growth begins. This will encourage the plant to branch and produce fuller growth and more flowers. To fill out thin plants, pinch the growing tips of all the stems back to 6.5 mm (1/4 inch) above the nearest leaf node.
Mulch the wallflower bed with 7.5 cm (3 inches) of organic mulch in winter once the temperatures drop. Wallflowers can survive temperatures down to -23 degrees C (-10F).
Wallflower plants are hardy in the UK's temperate climate.
Some wallflower varieties bloom from February to May, others from May to June.
Wallflowers need well-drained soil to grow. Never plant them in areas where water pools after a long rain. The roots (and eventually the plant) will drown and die.
After a light frost, your wallflower's leaves may droop. They'll perk back up when temperatures warm again. If the leaves remain drooping for a long time, the plant may have a disease. If any leaves show signs of bacterial infection, prune them and throw them away. If the leaves look fine other than a little droop, dig up the plant and check the roots. If they are mushy, black, or foul-smelling, throw the plant away.