Maximilian Sunflower

Maximilian sunflower (*Helianthus maximiliani*) is a tall, rhizomatous prairie perennial with narrow gray-green leaves and yellow flower heads that open from summer into fall. Garden references give a broad mature range of about 3–10 feet tall and 2–4 feet wide, while the USDA guide lists hardiness zones 3–9. [Missouri Botanical Garden](https://plantfinder.mobot.org/PlantFinderDetails.aspx?taxonid=261947) · [USDA plant guide](https://plants.usda.gov/DocumentLibrary/plantguide/pdf/pg_hema2.pdf) · [US Forest Service](https://research.fs.usda.gov/feis/species-reviews/helmax) ## Garden Use Reserve space at the back of a sunny border, meadow, or naturalized planting. The upright flower stems add late-season height, and the plant’s rhizomes slowly expand the clump after establishment. ## Growing Conditions Full sun is important; this sunflower does not tolerate shade. It grows in a range of soils, with deep, moist clay-like soils supporting taller growth, while established plants also tolerate dry-to-medium conditions. USDA and garden references show variation in mature size, so allow a generous spread around the plant. ## Maintenance Leave room for rhizomes and new shoots to expand. Stake exceptionally tall stems in exposed or rich, moist sites, and cut back old stems at the end of the season to make room for new growth. [USDA plant guide](https://plants.usda.gov/DocumentLibrary/plantguide/pdf/pg_hema2.pdf) · [Missouri Botanical Garden](https://plantfinder.mobot.org/PlantFinderDetails.aspx?taxonid=261947)