Helianthus debilis (beach sunflower, dune sunflower) is a reseeding annual in areas with freezing winter temperatures, but it is perennial in South Florida and other tropical areas. Native to the coastal dunes of Florida, Georgia and westward along coastal Alabama, Mississippi, Louisiana, and Texas, this member of the Asteraceae family grows naturally on sand dunes along with other native plants.

Plant Description
Bright yellow, single, daisy-like flowers with a contrasting black disk are about 2.5 inches in diameter. Expect the sunny flowers to be in bloom year round in tropical areas and all summer long in areas with freezing winter temperatures.

Leaves are simple, deltoid (wedge-shaped or like a capital delta), irregularly toothed and lobed, and grow either opposite or alternating along the stem. Leaves are 2 to 4 inches in length, and fruits are small kernels with an oily seed wall.

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Cultural Requirements
Beach sunflower is hardy in Zones 8-11. Choose small plants for an initial planting, and space them 18 to 24 inches apart. Water until they are well established, after which they require no irrigation except in extreme drought. As a matter of fact, over irrigation will cause the plants to decline.
Plant them in full sun in almost any well-drained soil, from acidic to alkaline. Growth is best in sandy soil. A light fertilization might be made while the plants are actively growing and filling in their space, but nutritional requirements are very low, and after establishment, no fertilizer is needed.

Be aware that plants will need rejuvenation after two or three years of growth. As plants become older, they become woody and exhausted. Remove dead and dying stems occasionally or cut them back by about one-third to invigorate the planting. Old plants can easily be pulled up to expose seeds to sunlight and encourage growth of new seedlings.

Pests and diseases are usually not of concern, but plants planted in less than ideal conditions for the species may develop some stem and leaf diseases. Powdery mildew can occur in damp, humid conditions, as can root rot.

ImageUses
Use beach sunflower as a groundcover or front-of the border flowering plant on sunny sites. It is attractive in mass plantings, cascading down a wall, as a dune or slope stabilizer, or as part of a roadside wildflower mix.

Native Americans used the flowers to produce pale green and purple-black colors for body painting and for dying their pottery, baskets, and fabrics. Floral arrangers are happy to pick a bouquet of this long-lasting sunflower to brighten interior spaces.

Propagation
Beach sunflower is easily started from seeds which germinate in place readily. Plants root wherever stems touch the ground, and they spread by underground rhizomes. Most likely, once you have a good stand of this plant, you will never need to purchase plants or seeds again. Seeds of cultivars may not come back true to type, and since the plants hybridize readily, seedlings may produce plants different from the parent.

Species, Varieties and Cultivars
According to the University of Florida, several varieties exist, including Helianthus debilis var. cupreatus with copper-red ray flowers; H. debilis var. purpureus with pink or violet rays; and H. debilis var. roseus with rose-colored ray flowers.

SevImageeral subspecies of Helianthus debilis are mentioned in various references. Among them are: subsp. dibilis, subsp. vestitusm, subsp. silvestris, subsp. praecox, subsp. tardiflorus, and subsp. cucumerifolius.

Cultivars include ‘Dazzler’ which has a chestnut and orange head, ‘Excelsior’ with a yellow, red, brown and purple head, ‘Orion’ which is deep yellow, and ‘Flora Sun’, a bright yellow cultivar. ‘Flora Sun’ is sold widely in Florida and surrounding states. It is adapted to Gulf Coast regions from Florida to Texas and to the Atlantic coasts from Florida to the southern coast of South Carolina. ‘Flora Sun’ and other cultivars and subspecies are not recommended for the west coast of Florida from Pinellas to Sarasota County because of the potential of genetic mixing with the rare west coast dune sunflower (H. debilis subsp. vestitus).

Any way you look at it, beach sunflower is an attractive, low-maintenance plant sporting bright sunflowers over a long season. Plant it in some out-of-the-way place well away from an irrigation system. Plant it for its outstanding color, its ease of care, its salt and drought tolerance, and for its attractiveness to us as well as to butterflies and other pollinators.
POSTHUMOUS THANKS TO FLORIDIAN FOR SHARING HER PHOTOGRAPHS, INCLUDING ONE OF DUNE SUNFLOWER ON CALADESI ISLAND STATE PARK IN PINELLAS COUNTY, FLORIDA.