Helianthus grosseserratus | Sawtooth Sunflower
Sawtooth sunflower, a tall perennial sunflower native to most of the U.S. east of the Rocky Mountains, it is most commonly found in Illinois and Missouri. Easy to grow. Plants reach anywhere from 3-12 ft tall. In dense colonies they’ll grow to 3-5 ft tall, but standalone plants can achieve heights up to 12 ft! The stout central stem is rather skinny, glabrous, and often reddish or reddish-purple in color. There is very little branching, except for some flowering stems that occur towards the top of the plant. The leaves are up to 8″ long and 2″ across, lanceolate, and either smooth or (as the common name suggests) serrate along their margins, and often slightly recurved, tending to fold upwards along the central veins, particularly during hot, dry weather. The upper side of the leaf is dark green with a light green, soft underside. The bright yellow blooms that look just like the sun, bloom in late summer, often into autumn.
Sawtooth Sunflowers are most commonly found growing in moist soils with high organic matter, but average garden soil suits them just fine, too. Plants are drought tolerant once established. Like some other sunflower varieties, Helianthus grosseserratus is clonal, spreading by shallow-rooted rhizomes. Similar to Maximilian Sunflower, Sawtooth Sunflower is an aggressive grower and can overtake more delicate plants if it doesn’t have enough room.
Sawtooth sunflower may be difficult to integrate into smaller gardens, but it does make a striking plant in bloom. One can make use of its habit of being shorter in dense colonies, and plant at least 5 plants in an area where they’ll really burst with pops of bright yellow. Sawtooth Sunflower is an excellent flower to include in a mixed meadow planting or prairie restoration.
Sunflowers are ecologically important. In some areas Sawtooth Sunflowers host 69 species of butterflies and moths! The flowers are a good late-season nectar and pollen source for bees and other pollinators, and also attract songbirds, especially goldfinches, who will start to pull the seed out of the flower head when it’s barely ripe.
Sun exposure: Full sun
Mature height: 5-12 ft
Mature width: 2-5 ft
Hardiness zones: 3-9