Getting it to bloom

Why won't my Mountain Cornflower bloom? (and how to make it flower)

Also called mountain cornflower, perennial cornflower, bachelor's button (Centaurea montana).

More about mountain cornflower

About Mountain Cornflower

Centaurea montana · also called mountain cornflower, perennial cornflower · flowering

Mountain cornflower is a clump-forming European perennial grown for its frilled, deep-blue thistle-like flowers with reddish centres from late spring into summer. Fully hardy and undemanding, it thrives in sun on most soils and self-seeds freely. Cut it back hard after the first flush to keep foliage fresh and trigger a second bloom.

Plant type: flowering

Watch for — Powdery mildew: White coating on leaves in late summer, worse in crowded, dry-rooted plants. Improve airflow, water at the base and cut foliage back after flowering for clean regrowth.

The reasons mountain cornflower isn't blooming

Almost every non-blooming mountain cornflower traces back to one of these, roughly in order of how common they are:

Too little sun — most of these need full sun (or very bright light) to flower well; shade gives leaves, not blooms.
Too much nitrogen feed, driving lush foliage at the expense of flowers (very common with general or lawn feeds).
The plant has not been deadheaded, so it stops flowering once it sets seed.
Irregular watering — drought or waterlogging at the budding stage makes buds abort.
It is still too young or was checked by a transplant and is rebuilding before flowering.

Feeding mountain cornflower a high-nitrogen general feed and growing it in too little sun — you get a big leafy plant and almost no flowers.

The fix — how to get mountain cornflower to flower

Maximise sun. Give mountain cornflower the sunniest spot you have — for most bedding and fruiting plants, more direct light directly means more flowers.
Switch the feed. Move off high-nitrogen feeds and use a higher-potassium "bloom" or tomato-type feed as it comes into flower.
Deadhead regularly. Remove spent flowers often to keep it producing more rather than stopping to set seed.
Water consistently. Keep moisture even through budding and flowering — drought-then-flood swings make buds drop.

Light and feeding do most of the heavy lifting here. Dial in the spot with the light guide for mountain cornflower and get the feeding right with the mountain cornflower fertilising schedule — the wrong feed (too much nitrogen) is one of the most common silent reasons a healthy plant makes leaves instead of flowers.

Bloom season and what to expect

Mountain Cornflower flowers across its growing season (mostly summer) and, kept fed and deadheaded, can bloom for many weeks or right up to frost.

Post-bloom care so it flowers again

Deadhead, keep feeding lightly, and many will rebloom; collect seed from the best plants at the end of the season if you want to grow them again.

For everything else this plant needs day to day, see the full mountain cornflower care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Mountain Cornflower blooming — frequently asked questions

Why won't my mountain cornflower flower?

Mountain Cornflower blooms on the season's growth given enough sun, warmth and the right feed — there is no cold or photoperiod trick, just good growing conditions and a bloom-leaning feed. The most common reason it is not happening: Too little sun — most of these need full sun (or very bright light) to flower well; shade gives leaves, not blooms.

How do I make mountain cornflower bloom?

Give mountain cornflower the sunniest spot you have — for most bedding and fruiting plants, more direct light directly means more flowers. Move off high-nitrogen feeds and use a higher-potassium "bloom" or tomato-type feed as it comes into flower.

When does mountain cornflower normally bloom?