Getting it to bloom

Why won't my Aromatic Aster bloom? (and how to make it flower)

Also called aromatic aster, shale aster, oblong-leaved aster (Symphyotrichum oblongifolium).

More about aromatic aster

About Aromatic Aster

Symphyotrichum oblongifolium · also called aromatic aster, shale aster · flowering

Aromatic aster is a compact, exceptionally tough native perennial forming dense mounds of aromatic foliage topped by violet-blue daisies in late autumn. Among the last asters to bloom, it thrives in hot, dry, lean soils and full sun, resists mildew well, and rarely needs staking. Its balsam-scented leaves and very late flowers make it a pollinator standout.

Plant type: flowering

Watch for — Sparse late bloom from early frost: As one of the latest asters to flower, a very early hard frost can cut blooming short. In cold areas, site it in a warm, sheltered, sunny spot to extend the display.

The reasons aromatic aster isn't blooming

Almost every non-blooming aromatic aster 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 aromatic aster 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 aromatic aster to flower

Maximise sun. Give aromatic aster 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 aromatic aster and get the feeding right with the aromatic aster 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

Aromatic Aster 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 aromatic aster care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Aromatic Aster blooming — frequently asked questions

Why won't my aromatic aster flower?

Aromatic Aster 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 aromatic aster bloom?

Give aromatic aster 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 aromatic aster normally bloom?