Butterfly weed

Butterfly weed: how do you recognise it?

Habit

Upright clump, 70 cm tall and 45 cm wide, with sturdy, hairy stems.

Leaves

Narrow and lance-shaped, scattered along the stem, dark green and rough to the touch.

Flower

Flat clusters of small, star-shaped flowers in bright orange, sometimes yellow or red, from July to September.

Fruit

Slender, spindle-shaped pods that split open; the seeds float away on silky tufts.

Roots

A thick, fleshy taproot that goes deep into the ground.

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

Why grow it?

• One of the brightest oranges in the border, from July to September.
• A true butterfly and bee plant, full of nectar.
• Drought tolerant thanks to its deep taproot: ideal for a dry, sunny spot or a gravel garden.
• Attractive pods with silky down in autumn.
• Lovely as a cut flower in a summer bouquet.

Butterfly weed: where does it grow best?

• Full sun: the sunnier and warmer, the more flowers.
• Poor to average, free-draining sandy or loamy soil, acid to neutral.
• Dry: wet feet, especially in winter, are its worst enemy.
• Plant 40–45 cm apart, in a spot where it can stay for years.

Light

Sun

Soil type

Sand or loam

Acidity

Acid or neutral

Moisture

Dry

Size

0.7 m tall, 0.45 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Purple coneflower: Another prairie plant, with pink flowers next to the orange.
• Catmint: Clouds of blue beside the orange, in the same dry soil.
• Woodland sage: Dark blue spikes for contrast, just as drought tolerant.
• Feather grass: Fine, swaying stems for a prairie feel.

Butterfly weed: when and how to plant it?

Plant in May–June.

1. Plant in May or June, when the soil has warmed up well.
2. Dig a deep hole so the taproot can go straight down.
3. Set the plant at the same depth as in its pot without damaging the root ball.
4. Leave 40–45 cm between plants.
5. Water straight away, then in dry spells for the first few weeks; after that hardly at all.
6. Mark the spot with a cane, as it comes up late in spring.

Care

Water

Only in dry spells in the first year; after that rain is enough.

Feeding

Not needed: it flowers best on poor soil.

Spent flowers

Cut off faded clusters for a second flush, or leave a few for the pods.

Marking

Put a label or cane by the plant: it only starts growing in May and is easily damaged when weeding.

Moving

Avoid moving it: the taproot breaks easily and the plant recovers poorly.

Tip: Mark the spot with a cane: it only comes up in May, so this stops you hoeing it out by mistake. Never move it, as the taproot recovers poorly.

Butterfly weed: when to prune it?

Pruning months: March and August.

When: Remove faded clusters in August; cut back the dead stems in March.

How:

• Cut faded clusters back to a side shoot: a second flush often follows.
• Leave a few stems standing in winter so you know where it is.
• In March cut the old stems back to 10 cm above the ground; the stumps mark the spot.

Caution: Wear gloves: the sap is poisonous and can irritate the skin and eyes.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

In February, put the seed in moist sand in the fridge for a month. Sow indoors in March–April, 1 cm deep, in deep pots at about 20 °C. Plant out the young plants in May–June without disturbing the root.

Division

Not recommended: the deep taproot divides poorly and divided plants often fail to establish.

Butterfly weed: how does it get through the winter?

Hardy to −30 °C.

• Hardy to about −30 °C: in Belgium it copes well with frost as long as the soil stays dry.
• Wet soil in winter makes the root rot: plant it in a free-draining, preferably slightly raised spot.
• The top growth dies back completely and only reappears in May: be patient.
• In a deep pot: keep the pot dry and sheltered in winter, for example under a canopy.

Diseases and pests

• Yellow aphids: Yellow to orange aphids on the shoot tips in summer. Spray off with water or wipe them away; ladybirds help.
• Root rot: After a wet winter the plant does not come back. Choose a drier, sandier spot.
• Hoed out: It comes up late and is often hoed out by mistake. Mark the spot.
• Slugs: They eat the young shoots in May. Pick them off in the evening.

Through the year

• February: Put the seed in the fridge for a month.
• March: Cut off old stems. Sow indoors.
• April: Sow indoors. Mark the spot and do not hoe there.
• May: The shoots appear. Plant. Watch for slugs.
• June: Plant. Water young plants in dry spells.
• July: Flowering begins. Butterflies and bees on the flowers.
• August: Remove faded clusters for a second flush. Watch for aphids.
• September: Last flowers. The pods ripen.
• October: Collect seed. Leave a few stems as markers.
• November: Rest. Make sure the spot does not get too wet.

Edible and useful

Not edible. All parts of milkweed are poisonous: the white milky sap contains cardiac glycosides, compounds that, like those of foxglove, act on the heart; monarch butterfly caterpillars store them and become poisonous themselves. Swallowing any causes vomiting, stomach ache and diarrhoea, and in larger amounts an irregular heartbeat. Grazing animals, especially sheep but also horses and cattle, can become seriously ill from it, even from dried plants in hay: do not plant it in or beside a field. The sap irritates the skin and eyes: wear gloves, do not rub your eyes and wash your hands after cutting back. If any is swallowed, call a poison centre (in Belgium 070 245 245) or your doctor at once.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Butterflies

Nectar for butterflies.

Did you know?

• Unlike most milkweeds, it has clear sap rather than white milky latex.
• In North America it is a food plant for monarch butterfly caterpillars.
• The seeds hang from silky tufts, which is why milkweeds are sometimes called silkweeds.