Getting it to bloom

Why won't my Butterfly bush bloom? (and how to make it flower)

Also called butterfly bush, summer lilac, orange eye butterfly bush (Buddleja davidii).

More about butterfly bush

About Butterfly bush

Buddleja davidii · also called butterfly bush, summer lilac · flowering

Butterfly bush is a fast-growing deciduous to semi-evergreen shrub famed for its long, fragrant flower spikes that attract butterflies, bees, and hoverflies through summer and autumn. Easy to grow in any well-drained soil and full sun. Hard annual pruning in early spring is essential to prevent it becoming leggy and to maximise bloom production.

Plant type: flowering

Watch for — Invasive / self-seeding: Produces prolific quantities of light seeds that spread via wind and water into waste ground, railway cuttings, and roadsides. Deadhead spent flower spikes promptly to prevent self-seeding. Sterile or low-fertility cultivars (e.g., 'Buzz' series, 'Lo & Behold') are available and preferred where invasiveness is a concern.

The reasons butterfly bush isn't blooming

Almost every non-blooming butterfly bush 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 butterfly bush 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 butterfly bush to flower

Maximise sun. Give butterfly bush 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 butterfly bush and get the feeding right with the butterfly bush 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

Butterfly bush 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 butterfly bush care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Butterfly bush blooming — frequently asked questions

Why won't my butterfly bush flower?

Butterfly bush 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 butterfly bush bloom?

Give butterfly bush 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 butterfly bush normally bloom?