Cypress spurge

Cypress spurge: how do you recognise it?

Habit

A low, dense mat of upright stems, 20–30 cm tall, that keeps spreading underground.

Leaves

Narrow and linear, 1–3 cm, fresh green to blue-green and crowded on the stem; yellow to orange in autumn.

Flowers

Small lime-yellow heads with rounded bracts, from April to June; later flushed orange to red.

Roots

Creeping rhizomes that throw up new shoots, sometimes quite a distance from the parent plant.

Sap

White, irritant milky sap in all parts of the plant.

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

Why grow it?

• A tough ground cover for poor, dry and sunny spots where little else will grow.
• Fine, feathery foliage that looks soft among stones, gravel and ornamental grasses.
• A long flowering season from April to June, with lime-yellow heads that later blush red.
• Native: bees and hoverflies visit the flowers, and the caterpillars of the rare spurge hawk-moth feed on the leaves.
• Very drought-tolerant and fully hardy, with yellow to orange autumn colour.

Cypress spurge: where does it grow best?

• Full sun; in shade it grows lax and flowers poorly.
• Poor sandy or loamy soil, acid, neutral or chalky; the poorer the soil, the more compact it stays.
• Dry, free-draining soil; it dislikes heavy, wet ground.
• Plant 30–40 cm apart; it will fill the space by itself.
• Choose a place where it is allowed to spread, such as a dry bank, a gravel garden or a bed surrounded by paving, not next to small, delicate plants.

Light

Sun

Soil type

Sand or loam

Acidity

Not fussy

Moisture

Dry

Size

0.3 m tall, 0.6 m wide

Hardiness

Hardy (to -35 °C)

Goes well with

• Blue fescue: Blue-grey tufts that contrast nicely with the fine, fresh green foliage.
• Catmint: Lavender-blue flowers in the same dry, sunny spot; vigorous enough to hold its own beside it.
• Thyme: A low, fragrant mat between stones; also a good bee plant.
• Ice plant: A sturdy succulent that flowers in late summer, long after the spurge has finished.

Cypress spurge: when and how to plant it?

Plant in March–April and September–October.

1. Plant in March–April or September–October.
2. Wear gloves to protect yourself from the sap.
3. To keep it in check, first sink a root barrier at least 30 cm deep, or plant it in a bottomless bucket.
4. Dig a hole slightly larger than the root ball; add no compost or fertiliser, as poor soil suits it better.
5. Set the plant at the same depth as it was in its pot, space plants 30–40 cm apart and water well.
6. Mulch with gravel or grit rather than compost.

Care

Watering

Only during the first weeks after planting, in dry weather. After that, never needed.

Feeding

Avoid it: fertiliser makes it floppy and even more invasive.

Mulching

A layer of gravel keeps the base dry and suppresses weeds.

Spent flowers

Shear off the flower heads after flowering, in June–July, to limit self-seeding and keep the mat compact.

Containing

Every spring and autumn, dig out runners that stray outside the area you want, roots and all.

Tip: Plant it where it is allowed to spread, for example on a dry bank or in a gravel bed with paving all round: then its urge to spread becomes an advantage.

Cypress spurge: when to prune it?

Pruning months: March and June–July.

When: After flowering, in June–July, shear off the spent heads. In March, cut away last year’s dead stems.

How:

• Shear the spent flower heads with shears to just above the foliage.
• That way it self-seeds less and the mat stays dense and low.
• In March, cut the dead stems down short before the new shoots appear.
• Wear gloves and eye protection, then wash your hands and your tools.

Caution: Do not leave prunings lying where children or animals can reach them, and never throw them into a pasture or near animal feed.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In March–April or September: dig up a piece of rhizome with shoots and replant it elsewhere. It nearly always takes.

Seed

Possible in spring in a pot outdoors, but rarely needed: it self-seeds.

Cypress spurge: how does it get through the winter?

Hardy to −35 °C.

• Extremely hardy, to about −35 °C: in Belgium it never needs protection.
• The stems die back in winter; in spring it shoots again from the rhizomes.
• Heavy, wet soil in winter is the only risk: the base may then rot.
• In a pot or trough it overwinters outdoors without trouble, as long as water can drain away.

Diseases and pests

• Spreading: Runners pop up among other plants and in the lawn. Dig them out regularly and use a root barrier.
• Rust: Stunted, unbranched stems with shorter, yellowish leaves that do not flower: a rust fungus. Dig out affected stems with their roots.
• Lax growth: Too much shade or soil that is too rich. Move it to a sunny, poor spot.
• Root rot: In wet soil the base rots and stems collapse. Improve drainage or move the plant.

Through the year

• March: Cut dead stems down short. Plant or divide.
• April: Flowering begins. Plant. Dig out runners outside the area.
• May: Full flower. Bees and hoverflies on the flowers.
• June: Last flowers. Shear off spent heads.
• July: Shear if not yet done. Weed out seedlings.
• September: Plant or divide. Dig out runners.
• October: Yellow to orange autumn colour. Plant.
• November: The stems die back. Dormant.

Edible and useful

Not edible. All parts of spurges contain a white, milky sap that is poisonous and caustic. On the skin it causes redness, itching and sometimes blisters; in the eyes it is extremely painful and can damage the cornea. Whenever you work on the plant, wear gloves, long sleeves and ideally safety glasses, do not rub your eyes, wash your hands and secateurs afterwards, and teach children not to break off the stems. If sap gets in your eyes, rinse them at once under running lukewarm water for at least a quarter of an hour and see a doctor. Swallowed, it burns the mouth and causes vomiting and stomach ache, in dogs and cats too; horses and livestock fall ill from it: never throw clippings into a field. 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.

Did you know?

• The name cyparissias refers to the cypress: the fine, crowded leaves recall a miniature cypress tree.
• Cypress spurge is an important food plant of the spurge hawk-moth, whose brightly coloured caterpillars eat its toxic leaves.
• A rust fungus of peas uses cypress spurge as an alternate host: infected stems stay unbranched, have shorter, yellowish leaves and do not flower.