Getting it to bloom

Why won't my Cobaea scandens bloom? (and how to make it flower)

Also called cup and saucer vine, cathedral bells, Mexican ivy (Cobaea scandens).

More about cobaea scandens

About Cobaea scandens

Cobaea scandens · also called cup and saucer vine, cathedral bells · flowering

Cobaea scandens, the cup and saucer vine, is a fast, tender perennial climber usually grown as an annual for its large bell-shaped flowers that open creamy-green and age to deep purple, each set in a leafy green ruff. It climbs rapidly by branched tendrils, flowers from summer to first frost, and quickly covers trellis, arches or fences in a single season.

Plant type: flowering

Watch for — All leaves, few flowers: Too much nitrogen or too little sun drives lush foliage with sparse bloom. Grow in full sun, keep feeding lean, and switch to a high-potash fertiliser.

The reasons cobaea scandens isn't blooming

Almost every non-blooming cobaea scandens 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 cobaea scandens 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 cobaea scandens to flower

Maximise sun. Give cobaea scandens 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 cobaea scandens and get the feeding right with the cobaea scandens 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

Cobaea scandens 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 cobaea scandens care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Cobaea scandens blooming — frequently asked questions

Why won't my cobaea scandens flower?

Cobaea scandens 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 cobaea scandens bloom?

Give cobaea scandens 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 cobaea scandens normally bloom?