Getting it to bloom

Why won't my Buddleja alternifolia bloom? (and how to make it flower)

Also called alternate-leaf butterfly bush, fountain butterfly bush (Buddleja alternifolia).

More about buddleja alternifolia

About Buddleja alternifolia

Buddleja alternifolia · also called alternate-leaf butterfly bush, fountain butterfly bush · flowering

Buddleja alternifolia is the fountain butterfly bush, a large arching shrub or small tree that wreathes its weeping previous-year branches in fragrant lilac-purple flowers in early summer. Unlike B. davidii it blooms on old wood, so prune right after flowering, not in spring. It loves full sun, free-draining soil, and tolerates drought once established.

Plant type: flowering

Watch for — Pruning at the wrong time: It flowers on old wood; cutting it back in spring removes the coming flowers. Prune immediately after flowering in early summer instead.

The reasons buddleja alternifolia isn't blooming

Almost every non-blooming buddleja alternifolia 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 buddleja alternifolia 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 buddleja alternifolia to flower

Maximise sun. Give buddleja alternifolia 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 buddleja alternifolia and get the feeding right with the buddleja alternifolia 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

Buddleja alternifolia 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 buddleja alternifolia care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Buddleja alternifolia blooming — frequently asked questions

Why won't my buddleja alternifolia flower?

Buddleja alternifolia 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 buddleja alternifolia bloom?

Give buddleja alternifolia 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 buddleja alternifolia normally bloom?