Sunflower ‘Mammoth’

Helianthus annuus ‘Mammoth’

Characteristics

Culture

An amazing giant Sunflower, ‘Mammoth’ produces enormous blooms – up to 1 foot  across. The large yellow flowers with brown centers top plants 7-12 feet tall and yield heavy loads of seeds. Fast and easy to grow, Mammoth sunflowers are great for creating a sun forest for kids, a tall annual hedge or screen. Sow seeds in the spring after the last average frost date. When around 3″ tall, seedlings should be thinned to 2 ft. apart. Edible seeds attract birds and make great snacks. To save seeds, cut the stem beneath flower heads when the backs of the flower heads turn yellow. Hang upside down and let dry in a cool, dry place for about a month. Cover with netting or a paper sack with holes to keep seeds from falling. But watch out for squirrels!

Noteworthy Characteristics

Helianthus annuus, the Common Sunflower, is native to dry plains, prairies, meadows and foothills in the western U.S., Canada and northern Mexico. It is a coarse, hairy, leafy, fast-growing annual that typically grows 5-10’ tall on stiff upright stalks. The species is commonly seen growing along roads, fences, fields and in waste areas west of the Mississippi River and is the state flower of Kansas. It is found on grasslands, range-lands, and prairies across Texas; and it’s native to Missouri.

Sunflower ‘Mammoth’ flower heads can span over a foot in diameter. This due to extensive crossing and hybridizing of the Common Sunflower which has resulted in cultivars that have greatly expanded the range of flower size and color. Large disk flowers give way to the familiar sunflower seeds. Large, ovate to triangular, sand-papery leaves to 12” long.

Problems

Rust, leaf fungal spots and powdery mildew are somewhat common. Caterpillars and beetles often chew on the foliage. May need staking, particularly if grown in exposed locations.

Garden Uses

Plant Sunflower ‘Mammoth’ for border rears or backgrounds.