Crop Rotation Group
Brassicas (Cabbage family)
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Soil
Fertile yet sharply drained soil with a neutral to slightly alkaline pH.
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Position
Full sun to part afternoon shade in hot summer areas.
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Frost tolerant
Yes. Perennial wallflowers survive winter temperatures to 5°F (-15°C), and grow as short-lived perennials in mild winter climates.
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Feeding
Drench with a liquid organic fertilizer when plants show vigorous new growth in late spring. Feed plants in containers monthly with a balanced water-soluble plant food.
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Companions
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Spacing
Single Plants: 1' 3" (40cm) each way (minimum)
Rows: 1' 3" (40cm) with 1' 3" (40cm) row gap (minimum)
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Sow and Plant
Start seeds indoors in early spring and grow them under bright lights until the weather becomes settled in spring. Or, start with purchased plants of a named variety. Plant at the same depth the plants grew in their containers and water well. A light mulch will deter weeds and help retain soil moisture until the plants are well rooted. Where summers are hot, wait until late summer or early fall to sow violet wallflower seeds, and grow the plants as winter annuals. Basal cuttings taken when plants are emerging from dormancy in late spring are easy to root in moist potting soil. If planting into containers, use 2 plants per 14-inch (35 cm) wide pot
Our Garden Planning Tool can produce a personalized calendar of when to sow, plant and harvest for your area.
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Notes
The flowers are popular among bees, butterflies and other pollinators. Perennial wallflowers grow best in climates with cool summer nights and may struggle in hot, humid areas. Plants become woody by their third year and may not bloom as well as younger plants. Renovate beds every three years or so in fall or spring, lifting and replanting the strongest crowns.
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Harvesting
Perennial wallflowers make excellent cut flowers if you don’t mind a few petals on the table. Cutting some of the old flower spikes will help extend bloom time, yet the plants will self-sow if you allow some stems to hold seed pods until they turn brown. With encouragement, perennial wallflowers will reseed for many years, with seedling sometimes appearing in nearby beds.
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Troubleshooting
Perennial wallflowers are considered deer resistant, but young plants may need protection from rabbits. Plants in containers need frequent trimming to keep them looking neat.
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