Prairie Sun

Black-eyed Susan

90d to harvest

Sun-warmed petals unfurl in a golden halo around a velvety, inky center—Prairie Sun Black-eyed Susan brings bold, radiant color to the garden from early summer into fall. The blooms are richly textured, with sturdy, upright stems that hold their form and a daisy-like presence that feels both lively and refined. Grow it for long-lasting landscape impact, striking cut-flower charm, and effortless pollinator appeal that turns sunny borders into a living tapestry.

Crop Dates

Growing note: In frost-free Zone 11b, grow this cool-season crop during the cooler dry season (October–February).

Milestone	Date
Start Indoors	—
Climate	Frost-Free Climate
Transplant / Sow Outdoors	Oct 1st
Harvest Begins	Dec 30th
Harvest Ends	Feb 28th

Crop Details

Trait	Value
Days to Maturity	90
Sun Requirements	Full Sun
Growth Habit	Upright
Support Needed	None
Planting Depth	Normal
Germination Temp (°F)	70
Min Soil Temp (°F)	55
Min Night Temp (°F)	40
Harden Off (days)	Not Required

Frequently Asked Questions

How do I prevent and treat powdery mildew on Rudbeckia hirta (Prairie Sun)?

Rudbeckia hirta commonly gets powdery mildew in late summer, especially when nights are humid and airflow is poor. At the first white, dusty patches, remove the worst leaves and water at the soil line (not overhead), then improve spacing and airflow around plants. If it keeps spreading, spray with a labeled fungicide for powdery mildew, following the label’s timing and reapplication interval.

How often should I water Prairie Sun Rudbeckia hirta during the main growing phase?

During active growth (after establishment), keep the soil consistently evenly moist but never soggy—aim for about 1 inch of water per week from rain and irrigation combined. Water deeply when the top 1–2 inches of soil feel dry to the touch, and let excess water drain; Rudbeckia hirta dislikes waterlogged soil. Once plants are established, you can stretch watering a bit, but don’t let them dry out completely during bloom.

How can I tell when Prairie Sun (Rudbeckia hirta) is ready to harvest?

For cut flowers, harvest when the central disk florets are fully developed and the bright yellow-orange rays are at their peak color, usually around day 90. Choose blooms that are just starting to open (fresh and firm) rather than those with browned, dried centers. If you’re harvesting seed, wait until the flower heads turn dark and the seeds look mature, then cut heads before they fully shed.