Planting and Growing Wallflowers (Erysimum)

When to Plant Wallflowers

Wallflower seeds can be planted in early spring after the last frosts and will bloom late spring to midsummer. Or, they can be planted in the fall, when the spring-flowering bulbs go into the ground for blooms in the following spring.

If planting in autumn, try to get them in the ground at least 4 to 6 weeks before the first fall frost to allow sufficient time for new roots to establish. 

Where to Plant Wallflowers

Wallflowers like full to partial sun in most locations. They’re fine in full sun in the northern areas of their hardiness range and will prefer afternoon shade in the hotter portions. If planting them in the ground, excellent drainage is key. They’re perfectly happy in scrappy, low-fertility soil. Imagine the drier, dustier side of a mountain. That’s the ticket.

These spring and early summer bloomers are perfect for bringing bright spring color to rock gardens and borders along fences. Use them for early color in cottage gardens when planted in large groupings. 

Wallflowers prefer soil pH neutral to slightly alkaline, about 6.5 to 8.0, although they’ll be fine in most soils as long as the extremes of pH are avoided.

How to Plant Wallflowers

Wallflowers are found in single nursery pots or bunches of bare roots, depending on your selected species and cultivar. You can also buy seeds for fall or early spring sowing.

For established plants:

• Remove all weeds, stones, roots, and rocks.
• Make a cereal bowl-shaped hole as deep as the root ball and twice as wide. Loosen the sides and bottom of the hole. Compacted soil makes it difficult for roots to penetrate and for water to drain.
• Remove the wallflower from its container and prune any circling or girdling roots.
• Test fit, check for depth, and ensure no roots are bent over or circling the hole. The top of the root ball should be at ground level.
• Backfill the hole with native soil, ensuring no air pockets around the roots.
• Keep filling the soil around the roots, firming it with your hands and watering when complete.

To start wallflowers from seed outdoors:

• Prepare the bed, working it loose, adding a bit of compost, and raking it smooth.
• Sow by scattering or broadcasting seeds on top of moist soil. Don’t cover them with soil, as they need light to germinate.
• If birds won’t leave your seeds alone, spread a very light layer of dry straw over the top. You should still be able to see soil peeking through. Break the straw into finer pieces easily by rubbing a handful vigorously between your palms as if you were trying to warm your hands.