Getting it to bloom

Why won't my Canna 'Roi Humbert' bloom? (and how to make it flower)

Also called Red King Humbert, King Humbert Canna (Canna 'Roi Humbert').

More about canna 'roi humbert'

About Canna 'Roi Humbert'

Canna 'Roi Humbert' · also called Red King Humbert, King Humbert Canna · flowering

Canna 'Roi Humbert' (also sold as Red King Humbert) is a bold, tall canna lily cultivar bearing scarlet-red flowers above bronze-purple foliage. It thrives in full sun with consistently moist, fertile soil. Plants die back in winter in cooler climates; rhizomes must be lifted and stored frost-free. Mildly toxic to pets.

Plant type: flowering

The reasons canna 'roi humbert' isn't blooming

Almost every non-blooming canna 'roi humbert' 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 canna 'roi humbert' 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 canna 'roi humbert' to flower

Maximise sun. Give canna 'roi humbert' 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 canna 'roi humbert' and get the feeding right with the canna 'roi humbert' 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

Canna 'Roi Humbert' 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 canna 'roi humbert' care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Canna 'Roi Humbert' blooming — frequently asked questions

Why won't my canna 'roi humbert' flower?

Canna 'Roi Humbert' 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 canna 'roi humbert' bloom?

Give canna 'roi humbert' 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 canna 'roi humbert' normally bloom?