Eastern bluestar

Eastern bluestar: how do you recognise it?

Habit

Sturdy clump of upright stems, 60–80 cm tall and as wide.

Leaves

Lance-shaped, 7–12 cm long, glossy mid-green and spread along the stems; golden yellow in autumn.

Flower

Pale blue stars about 1.5 cm across in clusters at the stem tips, in May–June.

Fruit

Slender, narrow pods that ripen in summer.

Roots

Deep and tough; an old clump is hard to divide.

Milky sap

Broken stems release a white milky sap that can irritate the skin.

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

Why grow it?

• Pale blue star flowers in May–June, a soft colour that is rare in early summer.
• Golden autumn colour, especially in a sunny spot.
• Bees visit the flowers.
• A sturdy, tidy clump that seldom flops in sun.
• Long-lived and rarely troubled by pests or diseases.

Eastern bluestar: where does it grow best?

• Sun or partial shade; in sun it stays more compact and colours better in autumn.
• Loam or clay, acid to neutral and preferably rich in humus.
• Moderately moist: neither drying out nor waterlogged. It tolerates drought less well than Arkansas bluestar.
• Allow 70–80 cm between plants.

Light

Sun and partial shade

Soil type

Loam or clay

Acidity

Acid or neutral

Moisture

Normal

Size

0.8 m tall, 0.8 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Peony: Flowers at the same time and is also a long-lived plant that likes to be left alone.
• Lady’s mantle: Frothy lime-yellow flowers at the front, lovely next to the pale blue.
• Hardy geranium: Loose ground cover that flowers for a long time.
• Michaelmas daisy: Purple flowers beside the golden autumn foliage.
• Purple moor grass: An ornamental grass that also turns golden in autumn.

Eastern bluestar: when and how to plant it?

Plant in March–May and September–October.

1. Plant from March to May or in September–October.
2. Dig a hole twice as wide as the pot and mix in some compost.
3. Set the plant at the same depth as in the pot and firm the soil well.
4. Keep 70–80 cm between plants; it looks best in a group of three or five.
5. Water in thoroughly straight away and keep the soil moist during the first season.
6. Spread a mulch of compost or leaf mould around the base.

Care

Watering

Regularly in the first year; after that, a good soaking now and then in dry summers.

Feeding

A thin layer of compost in March is enough; too much fertiliser makes the stems floppy.

Mulching

A layer of compost or leaf mould keeps the soil moist in summer.

Support

Rarely needed in sun. In partial shade it may fall open: cut it back by a third after flowering.

Moving

Best avoided: the older the clump, the better it looks.

Tip: Plant it in a group of three or five: one plant hardly stands out, but a group forms a soft blue cloud in May and a golden patch in October. Wait until March to prune, so you can fully enjoy the autumn colour.

Eastern bluestar: when to prune it?

Pruning months: March and June.

When: Cut down the old stems in March, before the new shoots appear. For a more compact plant, you can shorten it by a third in June, after flowering.

How:

• Leave the stems standing in autumn for the golden colour.
• In March, cut everything back to 5–10 cm above the ground.
• Cutting back after flowering does not cost you the autumn colour: the plant regrows.
• Wear gloves because of the milky sap.

Caution: The white milky sap can irritate the skin: wear gloves and do not rub your eyes.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In March–April, lift a clump and split it with a sharp spade into pieces, each with buds and roots.

Cuttings

In May–June, take 8–10 cm cuttings from young shoots and insert them in moist cutting compost. Wear gloves.

Seed

Sow in autumn in a pot left outdoors: the seed needs a cold spell to germinate.

Eastern bluestar: how does it get through the winter?

Hardy to −30 °C.

• Fully hardy, to about −30 °C: no protection is needed in Belgium.
• Leave the stems until March: they give structure and protect the crown.
• A large pot is possible; stand it against a wall in winter and make sure drainage is good.

Diseases and pests

• Falling open: In too much shade or soil that is too rich, the clump falls open. Move it to a sunnier spot, feed less and cut it back by a third after flowering.
• Slow start: In its first year it grows very little. That is normal: after 2–3 years it reaches full size.
• Drought: In a long dry spell the lower leaves turn yellow and the plant droops. Water generously and mulch the soil.
• Skin irritation: Red, itchy skin after pruning, caused by the milky sap. Wear gloves and long sleeves.

Through the year

• March: Cut down old stems. Add compost. Plant.
• April: Plant or divide.
• May: Flowering begins. Take cuttings.
• June: Flowering. Afterwards, cut back by a third if needed.
• July: Water in dry spells.
• September: Plant.
• October: Golden autumn colour. Plant.
• November: Leave the stems standing until March.

Edible and useful

Not edible. The white milky sap of amsonia is poisonous and irritates the skin and eyes; eating it causes vomiting, stomach ache and diarrhoea. The plant belongs to the same family as oleander and periwinkle. Wear gloves when cutting it back in autumn and when dividing, do not rub your eyes and wash your hands afterwards. Keep children and animals that chew plants, such as cats, dogs and rabbits, away, and do not throw the trimmings into a run or 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 genus name honours Charles Amson, an 18th-century physician from Virginia.
• The species name refers to Jacobus Theodorus Tabernaemontanus, a 16th-century German botanist and physician.
• It belongs to the dogbane family, for which the white milky sap is typical.