Common toadflax

How to recognise it

Habit

Perennial of 30–80 cm with straight, usually unbranched stems and creeping rhizomes; forms small colonies.

Leaf

Linear, 2–6 cm long and a few millimetres wide, grey-green and hairless, scattered and crowded along the stem.

Flower

Pale yellow with an orange palate, 2–3 cm including the long, straight spur; a closed ‘snapdragon’ in dense spikes at the top.

Fruit/Seed

Egg-shaped capsule with many flat, winged seeds that are carried by the wind.

Roots

Creeping rhizomes that send up new shoots; this is how it forms colonies.

Confusion with

Without flowers it resembles cypress spurge, but that oozes white milky sap when you snap a leaf; toadflax does not. The garden snapdragon has broader leaves and larger flowers without a long spur.

Flowering: June–October · Pruning: March and October

Why grow it?

• Flowers late and long, from June into October, when many other wild flowers have finished.
• A true bumblebee flower: only bumblebees can open the closed flower and reach the nectar in the long spur.
• Food plant for the caterpillars of a few moths, such as the toadflax pug, which lives in the flowers and seed capsules.
• An elegant wild flower for a dry, sunny verge, a rock garden or a gravel garden.
• Tolerates drought, poor soil and heat, and needs almost no care.

Common toadflax: where does it grow best?

• In the wild: road verges, railway embankments, dykes, waste ground, field margins, dry grassland and dunes.
• Full sun; in shade it hardly flowers.
• Dry to moist, well-drained soil: sand, gravel, loam or chalky soil, preferably not too rich.
• In the garden: a dry verge, a gravel garden, the foot of a sunny wall or a wildflower meadow on poor soil.

Goes well with

• Viper’s bugloss: Blue spikes on the same dry soil, also a bumblebee magnet.
• Wild marjoram: Pink flower clusters in July–September for butterflies and bees.
• Biting stonecrop: Yellow stars in June on the poorest, driest spots.
• Oxeye daisy: White in May–June, before the toadflax starts flowering.

Common toadflax: when and how to plant it?

1. Buy plants or seed from a native plant nursery. Never dig plants up from the wild.
2. Sow in September–October outdoors on bare ground or in pots left outside over winter: the cold helps germination.
3. Barely cover the fine seed and keep the soil lightly moist until it germinates.
4. Plant pot-grown plants in March–April or in October, 30–40 cm apart; the rhizomes fill the space by themselves.
5. Water after planting; after that, on most soils it needs no extra water.

Care

Water

Only after planting. It tolerates drought very well.

Feeding

Do not: poor soil keeps it compact and free-flowering.

Mowing

In a verge or wildflower meadow, mow only in October or March, so it can keep flowering and set seed.

Spreading

The rhizomes spread. In spring, cut off runners that go too far, or plant it where it has room.

Letting it seed

Let the capsules ripen: the winged seeds produce new plants in open spots.

Tip: Put toadflax in the driest, sunniest spot in your garden, such as along a gravel path or against a south-facing wall: that is where it flowers most freely and stays compact.

Pruning and mowing

Pruning months: March and October.

When: Leave the stems standing over winter and cut them in March; mow a wildflower meadow in October.

How:

• After flowering, leave the stems with their seed capsules: they look good in winter and shelter insects.
• In March, cut the dead stems back to just above the ground, before the new shoots appear.
• Mow a wildflower meadow late, in October, and remove the cuttings.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

Sow in September–October on bare ground or in pots left outside over winter; it germinates in spring.

Division

In March–April or October, cut off a piece of rhizome with shoots and replant it elsewhere.

Rhizome cuttings

Pieces of rhizome of about 5 cm, laid in a pot of sandy soil in spring, sprout easily.

Common toadflax: how does it get through the winter?

Hardy to −30 °C.

• The stems die back in autumn; the rhizomes survive winter.
• Fully hardy.
• Leave the dry stems with their capsules: they shelter small insects.
• In March–April the new grey-green shoots appear.

Diseases and pests

• Spreading: On loose, sandy soil it can spread strongly by its rhizomes. Cut off runners or plant it where it may spread.
• Few flowers: Too much shade or soil that is too rich. Move it to a sunny, poor spot.
• Holes in the spur: Short-tongued bumblebees sometimes bite a hole in the spur to reach the nectar. Harmless.
• Aphids: Sometimes aphids on the tips. Leave them for ladybirds and hoverfly larvae.

Through the year

• March: Cut down old stems. Plant or divide.
• April: New grey-green shoots. Plant.
• June: First flowers. Bumblebees visit.
• July: Full flower.
• August: Flowering. The first seed capsules form.
• September: Flowering and first ripe seed. Sow.
• October: Last flowers. Sow. Mow the wildflower meadow.
• December: Rest. Leave the dry stems standing.

Did you know?

• In 1744 Linnaeus described a strange form of toadflax with a star-shaped flower and five spurs, which he called Peloria; in 1999 it turned out that there is no error in the DNA code, but that one gene is ‘switched off’: an early known example of epigenetics.
• Linaria comes from the Latin linum, ‘flax’, after the flax-like leaves; the flower opens like a little mouth when you gently squeeze its sides.
• Europeans took toadflax to North America, where it has become a troublesome weed in many places.