Helianthus annuus

Plant Family

Asteraceae

Plant Botanical Name

Helianthus annuus

Photo by: JOHN RICKARD

Plant Common Name

Annual Sunflower

General Description

The sunflower is one of the best known garden flowers. Its big bold daisies track the sun, hence the common name. This warm season annual is uncommonly easy to grow and economically important for the production of sunflower seeds, for human consumption, cooking oil and birdseed, as well as cutflowers for the florist’s industry. It is a New World native that exists throughout the whole of North America down to Central America. Natural populations can vary widely in height but most are tall, upright with multiple side branches that extend from a sturdy central stem.

Sunflower leaves are very distinctive. They are large, medium green and heart-shaped with a rough, slightly hairy surface. Flowering typically occurs when temperatures are warm and nights short. Mature plants produce huge daisies that come in an array of sizes and harvest colors. The fresh flowers draw lots of insect pollinators, including bees and butterflies. It is important to allow the mature flowerheads to dry because the seeds within feed wild birds and mammals.

Grow sunflowers in full sun and average soil with good drainage. It is best to directly sow the seeds in the ground in the late spring. Tall plants with few side branches may require staking—sunflowers often fall when subjected to high winds and heavy rain. After flowering and setting seed, these short-lived annuals will die. If you desire continuous summer sunflowers, plant seeds every two weeks in succession from mid-spring to early summer. These outstanding annuals make superb additions to cutting garden or vegetable plots. Children also love them because they are fun to plant and grow. Dwarf cultivars like ‘Big Smile’ and ‘Teddy Bear’ are particularly desirable. Sunflower heads can also be cut with their seeds intact, dried indoors and brought outside to feed wildlife in winter.

Sunflowers emit a substance from their roots and germinating seeds that inhibits the germination of other seeds around them. Almost all cultivated sunflowers are day-neutral, which means they flower at any time of the year regardless of day/night length.

Characteristics

• AHS Heat Zone

  12 - 1

• Sunset Zone

  A1, A2, A3, H1, H2, 1a, 1b, 2a, 2b, 3a, 3b, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24

• Plant Type

  Annual

• Sun Exposure

  Full Sun

• Height

  2'-15' / 0.6m - 4.6m

• Width

  2'-4' / 0.6m - 1.2m

• Bloom Time

  Late Spring, Early Summer, Summer, Late Summer, Early Fall, Fall, Indeterminate

• Native To

  North America, Mexico, Central America

Growing Conditions

• Soil pH

  Neutral, Alkaline

• Soil Moisture

  Well Drained

• Soil type

  Clay, Loam, Sand

• Growth Rate

  Very Fast

• Water Requirements

  Drought Tolerant, Average Water

• Habit

  Upright/Erect

• Seasonal Interest

  Summer, Fall

Ornamental Features

• Flower Interest

  Showy

• Flower Color

  Yellow, Red, Orange, Gold, Burgundy, Bronze, Chocolate

• Flower Color Modifier

  Bicolor

• Fruit Color

  Chocolate, Ivory, Black

• Fruit Color Modifier

  Striped/Striated

• Foliage Color (Spring)

  Green

• Foliage Color (Summer)

  Green

• Foliage Color (Fall)

  Green

• Fragrant Flowers

  Yes

• Fragrant Fruit

  No

• Fragrant Foliage

  No

• Bark or Stem Fragrant

  No

• Flower Petal Number

  Single

• Repeat Bloomer

  No

• Showy Fruit

  No

• Edible Fruit

  Yes

• Showy Foliage

  No

• Foliage Texture

  Coarse

• Foliage Sheen

  Matte

• Evergreen

  No

• Showy Bark

  No

Special Characteristics

• Usage

  Container, Cutflower, Dried Flower/Everlasting, Edible, Herb / Vegetable, Mixed Border, Wildflower

• Sharp or Has Thorns

  No

• Invasive

  No

• Attracts

  Birds, Butterflies

• Self-Sowing

  Yes