Getting it to bloom

Why won't my Starry Rosinweed bloom? (and how to make it flower)

Also called Starry rosinweed, Starry silphium (Silphium asteriscus).

More about starry rosinweed

About Starry Rosinweed

Silphium asteriscus · also called Starry rosinweed, Starry silphium · flowering

Starry rosinweed is a native prairie perennial from the southeastern and central United States, thriving in open woodlands, roadsides, and dry to moderately moist meadows. It produces cheerful, daisy-like yellow flowers with a prominent central disk throughout summer, attracting bees, butterflies, and goldfinches to the seed heads. The single most important care fact is excellent drainage — like all silphiums, it will rot in soggy soil but is highly drought-tolerant once established. Toxicity to cats and dogs is not documented in the ASPCA database; classify with caution as mildly-toxic until confirmed.

Plant type: flowering

The reasons starry rosinweed isn't blooming

Almost every non-blooming starry rosinweed 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 starry rosinweed 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 starry rosinweed to flower

Maximise sun. Give starry rosinweed 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 starry rosinweed and get the feeding right with the starry rosinweed 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

Starry Rosinweed 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 starry rosinweed care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Starry Rosinweed blooming — frequently asked questions

Why won't my starry rosinweed flower?

Starry Rosinweed 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 starry rosinweed bloom?

Give starry rosinweed 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 starry rosinweed normally bloom?