Getting it to bloom

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

Also called calico aster, starved aster, side-flowering aster (Symphyotrichum lateriflorum).

More about calico aster

About Calico Aster

Symphyotrichum lateriflorum · also called calico aster, starved aster · flowering

Calico aster is an adaptable native perennial smothered in tiny white daisies along one-sided branches, each with centres that age from yellow to rose-purple, giving a speckled 'calico' look. Tolerant of shade, dry soil, and poor sites, it forms graceful, arching mounds in autumn and is a prolific late-season pollinator and host plant for butterflies.

Plant type: flowering

Watch for — Self-seeding: A prolific seeder that can sow itself widely. Deadhead after flowering if you want to limit volunteers, or leave seed heads for birds and winter structure.

The reasons calico aster isn't blooming

Almost every non-blooming calico 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 calico 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 calico aster to flower

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

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

Calico Aster blooming — frequently asked questions

Why won't my calico aster flower?

Calico 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 calico aster bloom?

Give calico 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 calico aster normally bloom?