Purple toadflax

Purple toadflax: how do you recognise it?

Habit

Slender, upright clump 60–80 cm tall and 25–30 cm wide, with many thin, airy stems.

Leaves

Narrow, linear, blue-green, 2–5 cm long, set closely along the stem.

Flower

Small snapdragon-like flowers 1 cm across with a spur, in long, dense spikes from June to September.

Colour

Violet-blue in the species; pink in ‘Canon Went’ and white in some cultivars.

Roots

Thin and fibrous; the plant is short-lived but self-seeds abundantly.

Flowering: June–September · Sowing: April–May · Plants: March–May and September–October · Pruning: March and July

Why grow it?

• Long, slender spikes of violet-blue flowers from June to September: an airy, natural feel.
• Very drought tolerant and almost maintenance-free on poor, sunny soil.
• Bumblebees and other long-tongued insects take nectar from the flowers.
• Self-seeds in crevices and gravel, giving you free new plants.
• The narrow, blue-green foliage and loose shape suit grasses and naturalistic borders.

Purple toadflax: where does it grow best?

• Full sun for the best flowering and the sturdiest growth.
• Poor, well-drained soil: sand or loam, acid to chalky. It also grows in gravel and wall crevices.
• Dry to reasonably moist; it tolerates drought well but not soil that is wet for long.
• Space plants 25–30 cm apart, ideally in a group, or let it self-seed freely in a gravel garden.

Light

Sun

Soil type

Sand or loam

Acidity

Not fussy

Moisture

Dry or normal

Size

0.8 m tall, 0.3 m wide

Hardiness

Hardy (to -25 °C)

Goes well with

• Ornamental grasses: Fine grass gives a natural, wild feel.
• Sage: Purple and blue together, with the same need for sun.
• Catmint: Blue flowers in the same sunny, well-drained soil.
• Purple coneflower: Warm tones next to the purple spikes.
• Stonecrop: Drought tolerant and low, with pink flower heads in late summer.

Purple toadflax: when and how to plant it?

Plant in March–May and September–October.

1. Plant between March and May or in September–October, when the soil is neither frozen nor waterlogged.
2. Dig a small hole; extra compost is not needed, and on heavy soil mix in coarse sand or grit.
3. Set the plant at the same depth as in its pot and lightly firm the soil.
4. Leave 25–30 cm between plants.
5. Water thoroughly after planting, then only in dry spells during the first year.
6. Sowing also works: in April–May scatter the seed on loose soil, barely cover it and thin the seedlings to 25–30 cm.

Care

Water

Water in dry spells during the first year. After that rain is enough, even in dry summers.

Feeding

None or hardly any: on poor soil it stands firm and flowers more richly.

Support

On poor soil it stands on its own. On rich soil or in wind the tall stems may bend; add a ring or twigs.

Spent spikes

Cut them in good time if you want to limit self-seeding, or let the seed ripen if you want free new plants.

Seedlings

Weed out or move surplus seedlings in spring while they are small.

Tip: A short-lived plant that self-seeds eagerly, even in wall crevices. Weed out surplus seedlings in spring.

Purple toadflax: when to prune it?

Pruning months: March and July.

When: In March to clear the old stems; after the first flowering, in July, for a second flush.

How:

• In March cut the old, dead stems down to 10 cm above the ground, before the new shoots appear.
• In July cut the spent spikes back by half: this often gives a second flush and stops all the seed from ripening.
• If you do not want self-sown seedlings, cut off the spikes before the seed ripens.
• Leave a few spikes in autumn if you want seedlings for next year.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

In April–May outdoors on loose, sunny soil, barely covered; thin the seedlings to 25–30 cm. Sowing in September also works. It also self-seeds by itself.

Cuttings

In May–June: take 8–10 cm cuttings from young, non-flowering shoots in sandy compost. Mainly used for cultivars that do not come true from seed.

Purple toadflax: how does it get through the winter?

Hardy to −25 °C.

• Fully hardy, to about −25 °C: no protection is needed in Belgian winters.
• The foliage stays partly green in mild winters; leave the stems until March, as they protect the clump.
• In a pot: use gritty soil and stand the pot in a sheltered spot so the roots do not freeze.

Diseases and pests

• Seedlings everywhere: It self-seeds abundantly, even into paving and crevices. Cut the spikes before the seed ripens and weed out the seedlings in spring.
• Flopping: On soil that is too rich or in shade it grows tall and floppy. Plant on poor, sunny soil and cut back in July.
• Aphids: On young shoots in spring. Ladybirds usually take care of them; otherwise rinse them off with water.
• Slugs: Young seedlings are eaten bare in spring. Collect slugs in the evening.

Through the year

• March: Cut old stems back to 10 cm. Plant.
• April: Sow and plant. Thin the seedlings.
• May: Sow and plant. Watch for slugs.
• June: Flowering begins.
• July: Full flower. After the first flowering, cut the spikes back.
• August: Flowering. Remove spent spikes to limit self-seeding.
• September: Last flowers. Plant or sow. Let the seed ripen if you want it.
• October: Plant. Clear away seedheads.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• The genus name Linaria comes from the Latin ‘linum’, flax, because the narrow leaves resemble those of flax.
• The flowers have a spur filled with nectar: mainly long-tongued bumblebees can reach it.
• The pink cultivar ‘Canon Went’ is a well-known garden form of this species.