Dense blazing star

Dense blazing star: how do you recognise it?

Habit

Upright clump 60–90 cm tall and 30–45 cm wide; ‘Kobold’ stays around 40–50 cm.

Leaves

Narrow, linear and grass-like, crowded along the stem; longest at the base.

Flower

Dense spikes of 15–40 cm made up of small, fluffy flower heads that open from the top down, from July to September.

Colour

Purple-pink to lilac; white cultivars also exist.

Corm

A flattened, round corm sitting just below the surface, which rots quickly in wet soil.

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

Why grow it?

• Flowers from July to September with straight, eye-catching spikes that give a border structure.
• A real magnet for bees, bumblebees and butterflies.
• An excellent cut flower: the spikes last long in a vase and can also be dried.
• Fully hardy and low-maintenance: in lean soil it needs no staking and hardly any pruning.
• Takes up little space and suits a small garden or a large pot.

Dense blazing star: where does it grow best?

• Full sun: in shade the spikes flop and it flowers less.
• Free-draining sandy or loamy soil, acid to neutral; avoid heavy clay that stays wet in winter.
• Normally moist in summer but never waterlogged in winter, or the corms will rot.
• Plant 25–30 cm apart, preferably in groups of five or more for a good effect.

Light

Sun

Soil type

Sand or loam

Acidity

Acid or neutral

Moisture

Normal

Size

0.7 m tall, 0.3 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Coneflower: The same prairie feel: round flowers beside straight spikes, in the same full sun.
• Switchgrass: Airy plumes that combine well with the stiff spikes.
• Black-eyed Susan: Yellow beside purple, flowering at the same time.
• Globe thistle: Blue globes beside purple spikes, both loved by bees.
• Catmint: A soft blue edging at the front of the border.

Dense blazing star: when and how to plant it?

Plant in March–May and October.

1. Plant the corms from March to May or in October, when the soil is neither frozen nor too wet.
2. Loosen the soil and work in some coarse sand or fine gravel if it is heavy.
3. Set the corms 5 cm deep with the buds facing up; if in doubt, lay them on their side. Pot-grown plants go in at the same depth as in the pot.
4. Leave 25–30 cm between corms.
5. Water well once, then only when the soil feels dry, until the leaves appear.

Care

Watering

Once established, only during long dry spells. In a pot, regularly, but never leave water in the saucer.

Feeding

Not needed in ordinary garden soil. In poor soil, a thin layer of compost in April. Too much fertiliser gives floppy spikes.

Support

In rich soil or a windy spot the spikes may fall over; a few twiggy sticks or a ring help.

Cutting

Cut the spikes when the top third is open; they carry on flowering in the vase.

Deadheading

Cut faded spikes back to just above the leaves, or leave them if you want to collect seed.

Dividing

Every 3–4 years, lift and divide the clump if it flowers less or goes bare in the middle.

Tip: For the vase, cut when the top third of the spike is open, and always leave some of the foliage so the corm can build up strength for next year.

Dense blazing star: when to prune it?

Pruning months: March.

When: Dense blazing star needs hardly any pruning. Cut away the dead stems and leaves in March, before the new shoots appear.

How:

• In summer, cut faded spikes back to just above the leaves if you do not want seed.
• Leave the foliage after flowering until it yellows: this lets the corm build up reserves for next year.
• In March, cut all dead stems and leaves back to just above the ground.

Caution: Do not hoe or rake deeply around the plant: the corms sit just below the surface.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In March–April or in October, lift the clump and cut the corms with a sharp knife into pieces that each have at least one bud. Replant straight away, 5 cm deep.

Seed

Sow seed of the species in autumn in a pot left outdoors: it germinates better after a cold spell. Young plants take 2–3 years to flower.

Dense blazing star: how does it get through the winter?

Hardy to −30 °C.

• Fully hardy, to about −30 °C: frost is no problem in Belgium.
• Wet soil is a risk, though: in standing water the corms rot. Choose a well-drained spot.
• In a pot: stand it on pot feet against a wall, out of the worst of the rain.

Diseases and pests

• Corm rot: The plant fails to come up in spring or wilts from the base. The cause is wet soil in winter. Plant new corms in a drier spot or a raised bed.
• Voles: Corms disappear or are gnawed. Plant them in a basket of fine wire mesh.
• Slugs: They eat the young shoots in April–May. Pick them off in the evening or set a beer trap.
• Flopping spikes: In soil that is too rich or in too much shade the stems go weak. Less fertiliser, more sun and some support help.

Through the year

• March: Cut away dead stems and leaves. Plant corms or divide clumps.
• April: Planting. Watch for slugs on the young shoots.
• May: Last planting month in spring. Stake plants in windy spots.
• June: Growth. Water during long dry spells.
• July: Flowering begins. Cut spikes for a bouquet.
• August: Full flower. Deadhead or leave spikes for seed.
• September: Last flowers. Collect seed.
• October: Plant corms or divide clumps. Sow seed in a pot outdoors.
• November: The foliage dies back. Make sure no water stands around the plant.
• December: Rest.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Butterflies

Nectar for butterflies.

Did you know?

• The spikes open from the top down, whereas most spike-shaped flower heads start at the bottom.
• Blazing star is grown on a large scale as a cut flower and often appears in florists’ bouquets.
• Its Dutch name, lampepoetser, compares the spikes to a brush for cleaning lamp glasses.