Perennial cornflower (Centaurea montana)

Also known as: Mountain bluet, Bachelor's button, Knapweed, Great blue-bottle

The perennial cornflower, or Centaurea montana, is native to the mountainous meadows and open woodlands of Europe, particularly in regions like the Alps and Pyrenees. It is often cultivated as a garden plant and valued for its ornamental flowers. While not edible, it has traditional medicinal uses in parts of Central Europe. Additionally, it has become invasive in areas such as British Columbia. The plant is also known for attracting various pollinators, including bees, butterflies, and moths.

In This Article

Care Tips Water Sunlight Temperature Soil Fertilize Prune Propagation Repotting

Attributes of Perennial cornflower

Lifespan

Perennial, Annual

Plant Type

Herb

Plant Height

30 cm to 70 cm

Spread

30 cm to 60 cm

Leaf Color

Green Gray

Flower Size

5 cm

Flower Color

Blue Red White Pink Violet

Images of Perennial cornflower

Quickly Identify Perennial cornflower

Distinct solitary blooms with fringed, vibrant blue petals and reddish-blue center.

Involucre bracts with black edging framing the striking flower center.

Lance-shaped, green leaves up to 7 inches (18 cm) long, with prominent parallel veins.

Erect, hairy stems reaching 1-2 feet (30-60 cm) in height, often unbranched.

Fruit with fine, straw-colored texture and tuft of light brown bristles at tip.

Scientific Classification of Perennial cornflower

Phylum

Vascular plants

Class

Dicotyledons

Order

Asters bellflowers fanflowers and allies

Family

Daisy

Genus

Centaury

Species

Perennial cornflower

Planting and Growing of Perennial cornflower

Care Difficulty

Easy

Watering Schedule

Every 4 days

Sunlight Requirements

Full sun

Sunshine Duration

6-12 hours

Ideal Temperature

60-70℉

Soil Type

Potting Mix, Peat Mix

Soil pH

6.5-7.5

Fertilizer Type

Balanced

Pruning Season

Spring, Summer

Pruning Area

Branches, Leaves

Pruning Frequency

2 times a year

Repotting Season

Spring

Pot Type

Plastic, Terracotta

How to Water Perennial cornflower?

When watering Centaurea montana, aim to thoroughly soak the soil so it reaches a depth of 6 to 8 inches. This ensures that the roots receive sufficient moisture without waterlogging. A typical amount is around 500 ml, depending on soil type and environmental conditions.

What are the symptoms of an underwatered Perennial cornflower? ›

What should I do if my Perennial cornflower is not getting enough water? ›

What are the symptoms of an overwatered Perennial cornflower? ›

How to save an overwatered Perennial cornflower? ›

More About Watering Techniques→

What Are the Sunlight Requirements for Perennial cornflower?

Sunlight Requirements: Full sun, Partial sun

Duration of light: 6 to 8 hours

Centaurea montana thrives with a light exposure of at least six to eight hours of sun daily, preferably in the morning to midday. Such lighting conditions ensure vibrant blooms and vigorous growth.

How much sunlight does Centaurea montana need? ›

What can be done to ensure Centaurea montana gets its ideal light? ›

What are the effects of ideal lighting on Centaurea montana? ›

More About Sunlight Requirements Techniques→

What Is the Ideal Temperature Range for Perennial cornflower?

Ideal Temperature: 60 ~ 70℉

Centaurea montana flourishes best in temperatures ranging from 60°F to 70°F. Within this range, the plant receives just the right conditions for optimum growth and blooming. Maintaining these temperatures ensures that the plant uses its resources most efficiently for photosynthesis and nutrient uptake.

What Soil is Best for Perennial cornflower?

Soil type: Sandy soil, Loam

Soil PH: 6.5 ~ 7.5

Centaurea montana thrives in well-drained soil, which prevents waterlogging and root rot. This kind of soil ensures that the plant's roots receive enough oxygen and helps the plant maintain healthy growth. This plant prefers moderately fertile soil, which provides a balanced supply of nutrients without encouraging leggy growth. Fertile soil supports robust flowering and overall vigor. Centaurea montana grows best in soil with a pH ranging from neutral to slightly alkaline, between 6.5 and 7.5. This pH level allows for optimal nutrient uptake, fostering strong plant development. More About Soil→

How to Fertilize Perennial cornflower?

Fertilizer type: Balanced

When fertilizing Centaurea montana, it's essential to opt for a balanced 10-10-10 or 20-20-20 formulation, ensuring that you use approximately 1/2 to 1 full teaspoon per square foot of soil. This will provide the right blend of nutrients without overwhelming the plant and risking nutrient burn. More About Fertilizing Techniques→

How to Prune Perennial cornflower?

Pruning Time: Spring, Summer

In early spring, as new growth emerges from the base, cut back old and dead stems to ground level. This promotes healthy new growth and helps rejuvenate the plant after its winter dormancy. Throughout the blooming season, regularly remove spent flowers by snipping just below the bloom. Deadheading not only tidies up the plant but also stimulates more flowering by redirecting energy into producing new buds. In mid-summer, once the main flowering flush is over, cut back the entire plant by about a third. This encourages a second wave of blooms and helps keep the plant from becoming leggy and untidy. More About Pruning Techniques→

How to Propagate Perennial cornflower plant?

Propagate Time: Spring, Early summer

Begin by filling a seed tray with a well-draining potting mix. Sow Centaurea montana seeds on the surface and lightly cover them with soil. Water them gently and cover the tray with a dome to retain humidity.

For division, lift the mature plant from the ground in early spring. Use a sharp garden knife to divide the root ball into sections, ensuring each section has roots attached. Replant the divisions immediately into prepared soil.

Select healthy roots from a mature Centaurea montana plant in early summer. Cut 3-4 inch sections, ensuring at least one root nodule per section. Plant these cuttings horizontally in a pot with moistened potting mix.

More About Propagating Techniques→

How to Repot Perennial cornflower plant?

Repotting frequency: Once every 2-3 years

Signs that your Centaurea montana needs repotting include slowed growth, root bound symptoms like roots coming out of drainage holes, and frequent need for watering. These indicate the plant has outgrown its pot and would benefit from more space and fresh soil.

Opt for a pot that is slightly larger than the current one, ideally 1-2 inches bigger in diameter. Clay pots with drainage holes are excellent, as they allow excess moisture to escape, reducing the risk of root rot and ensuring healthy plant growth.

A well-draining garden soil is ideal. Mix regular potting soil with sand and perlite to improve aeration and drainage, which helps prevent waterlogging and provides a robust environment for roots to thrive.