Getting it to bloom

Why won't my Bougainvillea 'Barbara Karst' bloom? (and how to make it flower)

Also called Red Bougainvillea, Paper Flower (Bougainvillea 'Barbara Karst').

More about bougainvillea 'barbara karst'

About Bougainvillea 'Barbara Karst'

Bougainvillea 'Barbara Karst' · also called Red Bougainvillea, Paper Flower · flowering

Bougainvillea 'Barbara Karst' is a vigorous evergreen climber famous for masses of vivid magenta-red bracts almost year-round in warm climates. It thrives on heat, full sun, and lean, fast-draining soil, and actually flowers harder when kept slightly dry. Thorny and fast, it covers walls and fences quickly but resents soggy roots and frost.

Plant type: flowering

Watch for — Lush leaves, few bracts: Caused by too much water or nitrogen; let the plant dry between waterings and switch to a low-nitrogen bloom feed to trigger colour.

The reasons bougainvillea 'barbara karst' isn't blooming

Almost every non-blooming bougainvillea 'barbara karst' 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 bougainvillea 'barbara karst' 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 bougainvillea 'barbara karst' to flower

Maximise sun. Give bougainvillea 'barbara karst' 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 bougainvillea 'barbara karst' and get the feeding right with the bougainvillea 'barbara karst' 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

Bougainvillea 'Barbara Karst' 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 bougainvillea 'barbara karst' care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Bougainvillea 'Barbara Karst' blooming — frequently asked questions

Why won't my bougainvillea 'barbara karst' flower?

Bougainvillea 'Barbara Karst' 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 bougainvillea 'barbara karst' bloom?

Give bougainvillea 'barbara karst' 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 bougainvillea 'barbara karst' normally bloom?