Western wallflower.

At a glance

Care level

Easy

Plant type

Biennial or short lived perennial

Light

Full sun

Indoor light

Direct sun

Water

Every 7 to 14 days

Mature size

2 to 3 feet

Growth rate

Medium

Hardiness

USDA 4 to 9

Bloom time

Mid to late spring

Care

Plant this beauty in a spot with excellent drainage to prevent root rot. Keep an eye out for aphids on the flower buds during the spring. Deadheading spent blooms can encourage a longer flowering season.

Watering

Water deeply once the top few inches of soil feel dry to the touch.

Feeding

Apply a balanced fertilizer sparingly during the growing season.

Pruning

Remove faded flower stalks to keep the plant tidy and encourage growth.

Repotting

Repot only if the plant becomes rootbound in its container.

Soil

Sandy or rocky well drained soil

Soil pH

Neutral to slightly alkaline

Temperature

-20 to 30°C

Humidity

20 to 50%

Drought tolerance

High

Lifespan

Short lived perennial, typically 2 to 4 years.

Fragrance

Strong

Deer and rabbits

Moderate

Safety

People

The plant contains cardiac glycosides which are toxic if consumed in large quantities.

Children

Keep children away from the plant to prevent accidental ingestion of the leaves or flowers.

Contact allergens

The sap can cause mild skin irritation in sensitive individuals.

Airborne allergens

The pollen may trigger mild hay fever symptoms in some people.

Edibility

This plant is not considered edible and may cause stomach upset if ingested.

How to identify it

• Clusters of fragrant four petaled flowers
• Narrow lance shaped leaves
• Sturdy upright flowering stems
• Seed pods are long and slender

Height

0.3 to 0.9m

Spread

0.2 to 0.4m

Leaves

gray-green, semi-evergreen

Flowers

orange, yellow, red, purple, 1 to 2cm

Fruit

brown, Summer

Problems to watch for

• Downy mildew · Appears as yellow patches on leaves during periods of high humidity.
• Aphids · Small insects that cluster on new growth and flower buds.

Growing it

Propagation

seed

When to plant

spring, fall

Overwintering

Ensure the soil is very well drained to prevent crown rot during wet winter months. No special covering is needed as it is quite cold hardy.

In containers

It grows well in containers if provided with excellent drainage and a gritty potting mix.

Pair this plant with other drought tolerant species that prefer lean, sandy soils.

Grows well with

• California Poppy · They share similar requirements for sun and well drained soil.
• Penstemon · These plants provide a nice contrast in flower shape and bloom time.

Similar species

• Wallflower · It is a popular garden relative with similar flower forms.

Science

Family

Brassicaceae

Genus

Erysimum

Order

Brassicales

Class

Magnoliopsida

Native range

Western North America

Conservation

It is not currently listed as endangered or threatened in its native range.

It grows in open, sunny habitats like rocky slopes and meadows where it relies on its deep taproot to find moisture.

Value to wildlife

nectar source

Pollinators

bees, butterflies

Uses

rock gardens, pollinator borders, native plant landscapes

Taxonomy resolved against GBIF.

Questions people ask

Does it need deadheading?

Yes, removing spent blooms can encourage a longer flowering period.

Is it drought tolerant?

Once established, it handles dry spells quite well.

Where the name comes from

The name capitatum refers to the flowers being arranged in a dense, head like cluster.

Good to know

• It is commonly known as the western wallflower.
• The flowers are highly fragrant in the evening.
• It thrives in rocky, well drained soils where other plants struggle.
• The genus name Erysimum comes from the Greek word for to draw up or blister.

Also in

• Drought-tolerant plants