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Annual (Common) sunflower (Helianthus annuus):
Mother Nature's Montrose Garden
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Unexpected
surprises (both good and bad) keep popping up in Mother Nature’s Montrose Garden. A welcome gift, planted by the previous owner,
is a small stand of Annual sunflowers.
And nothing says ‘summer’ quite like Helianthus annuus. The scientific name is pronounced: hee-lee-ANN-thus ANN-you-us. And both the scientific and common names are
the same – Annual sunflower. This
sunflower is also known as the Common sunflower, Hopi sunflower, Wild
sunflower, and, in Spanish, as Girasol, Mirasol, Flor de Sol.
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Annual (Common) sunflower: along roadside,
San Miguel County, CO
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Helianthus annuus is
a plant of western North America, from SW Canada to Mexico. It grows in most
Colorado counties, at elevations less than about 7000 ft. (1900 m.). It’s the
common tall sunflower you see growing along roadsides this time of year (above).
There are approximately 50 species of Helianthus in N. America, with most
species in the American Southwest and in Central America. Both the genus and
species were named by Linnaeus. All sunflower-like
plants are members of the family Asteraceae; these plants are often
known as composites (more on this later).
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Everyone loves Annual (Common)
sunflower (Helianthus annuus)
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Annual
sunflower grows in places where there is adequate – but not too much – soil moisture.
It’s found in sunny places in shrublands, along roads and agricultural fields
and in gardens. Common sunflower is one
of the most easily recognizable of flowers.
And it’s loved – and planted - by people around the world. In fact, it’s become a weed in some places.
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Annual (Common) sunflower
(Helianthus annuus): young plants
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Annual
sunflower is an herbaceous annual. It completes its entire life cycle – from seed,
to seedling, to mature plant, to flowering, then back to seed – in a single
year. Seeds germinate when moist soil
warms up in the spring. Then the plants grow quickly as the days lengthen into
summer (above).
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Annual (Common) sunflower
(Helianthus annuus): growth habit
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Annual
sunflower is a robust plant, growing from 3-10 ft (1-3 m.) tall. Plants can vary widely in their
characteristics. Some have a stout
central stem, while others have more slender, graceful stems and flower stalks.
The wild forms are usually multi-branched (see above). The variability in form, foliage and even
color have made this plant a favorite for plant breeders. In fact, most of the sunflowers grown as
agricultural crops – as well as the brightly colored orange and brown garden
varieties – are cultivars of Helianthus annuus.
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Annual (Common) sunflower
(Helianthus annuus): cultivar
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Annual (Common) sunflower
(Helianthus annuus): foliage
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Annual (Common) sunflower
(Helianthus annuus): leaves
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The
leaves of the Common sunflower are usually heart-shaped to oval, on long stems
(petioles). The leaves are simple and usually
opposite low on the plant; they may be alternate higher up. The leaves are coarsely toothed and the
entire plant is densely covered with plant hairs (trichomes) and glands (below). These are likely to defend the plant from
predators such as caterpillars and snails.
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Annual (Common) sunflower
(Helianthus annuus): trichomes
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Annual (Common) sunflower
(Helianthus annuus): flower heads
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The
flower heads (what most people think of as the ‘flower’) are actually composed
of two types of flowers. The flat,
yellow ray flowers (look like petals) surround the central disk flowers. In this species, the disk flowers are usually
dark red/purple to brown and are crowded closely together in the center of the
flower head. The ray flowers attract pollinators
with their bright color; the disk flowers are what produce the seeds. Plants bloom from mid-summer into fall.
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Annual (Common) sunflower
(Helianthus annuus): bee pollinators
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One good
reason to plant Annual sunflower is the wildlife it attracts. Helianthus annuus (and other
sunflowers) is insect pollinated. The long-tongued bees are the most important
pollinators, including honeybees, bumblebees, Miner bees, and Leaf-Cutting bees. One of our favorites, which is commonly seen
in Colorado, is the Long-horned bee (see below). Bee flies, flower flies, butterflies and
other insects also serve as pollinators.
If you like watching insects, this is certainly a good plant for your
garden!
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Annual (Common) sunflower
(Helianthus annuus): Longhorn bee
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The
seeds of Common sunflower look like small versions of the sunflower seeds we
eat. The seeds ripen in late summer or
fall. The seeds are enjoyed by a wide
range of seed-eating birds, as well as by smaller animals. They once were an important food source for
native peoples where ever they grew.
Sunflowers
are easy to grow. They will grow in just
about any type of soil. They do need full sun or they will get leggy and not
flower well. Taller varieties should be protected from wind or staked. And they need occasional water (once a week or
so until flowering wanes). In places
with good rainfall, they may need no supplemental water. They have a deep taproot, and are more
drought tolerant than many annual wildflowers.
But don’t overwater (especially keep leaves dry) as sunflowers are
susceptible to powdery mildew and other fungal diseases. For a complete list of pests and diseases
see reference 1, below.
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Annual (Common) sunflower (Helianthus
annuus): dried foliage in fall
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Annual (Common) sunflower (Helianthus annuus):
goldfinch eats seeds
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We
advocate leaving the seed heads on the plants until birds have had their fill.
The dried plants are attractive in their own right (above). And who can resist watching finches and other
seed eating birds filling up for the journey south. In late fall or winter, cut plants down to
the ground (leave the roots – they will decompose, adding nutrients to the
soil). We’ve found that once a sunflower
patch is established it can re-seed itself.
The birds don’t eat all the seed; some is left to sprout in the spring.
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Annual (Common) sunflower (Helianthus
annuus): patch has re-seeded over 5 years
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Annual
sunflower can be used in many ways in the garden. It makes a nice summer accent plant, and is
useful for filling in empty spots in the garden. If you have room, the plants are spectacular
when massed. They look great at the back of flower beds or cottage garden displays.
If you just have a small porch, they can
even be grown in large containers. Dwarf cultivars are useful in flower beds
and containers. And, of course, you’ll want
to include the sunflowers in any type of habitat garden. Sunflowers are among our best all-round habitat
plants.
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Annual (Common) sunflower (Helianthus
annuus): great filler or accent plant
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Annual (Common) sunflower
(Helianthus annuus): in a container
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Annual (Common) sunflower (Helianthus
annuus): spectacular massed
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Sunflowers
add a special cheery note to the summer garden.
We suspect that’s one reason why they are so popular. But Annual sunflower is also an important
heritage plant. It’s been cultivated for
thousands of years in the Southwest and Mexico [2]. Cultivars are grown commercially for seed, sunflower
oil and bird food. The stems are used to make paper and the whole plant as
yellow-green natural dye. Plant parts are
used as plant-based medicinals by many native cultures, with uses ranging from diuretic,
expectorant and antibiotic. The species
has often been used for colds, coughs, throat, and lung ailments and insect
bites [1,3].
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Annual (Common) sunflower (Helianthus
annuus): Colorado heritage plant
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In
summary, Helianthus annuus is a cheery, easy-to-grow summer wildflower. It
is an excellent habitat plant. It looks
equally at home in the native plant garden, the cottage garden and the
cultivated flower bed. It’s fairly drought
tolerant and a number of interesting cultivars are available. It’s one of those heritage plants that’s
right at home in a Colorado garden.
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Annual (Common) sunflower (Helianthus annuus):
summer color in a water-wise garden, California
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For a gardening information sheet see: http://www.slideshare.net/cvadheim/gardening-sheet-helianthus-annuus
For more
pictures of this plant see: http://www.slideshare.net/cvadheim/helianthus-annuus-web-show
For plant
information sheets on other native plants see: http://nativeplantscsudh.blogspot.com/p/gallery-of-native-plants_17.html
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- https://hort.purdue.edu/newcrop/duke_energy/Helianthus_annuus.html
- http://www.museums.org.za/bio/plants/asteraceae/helianthus_annuus.htm
- http://southwestdesertflora.com/WebsiteFolders/All_Species/Asteraceae/Helianthus%20annuus,%20Common%20Sunflower.html
We
welcome your comments (below). You can
also send your questions to: mothernaturesbackyard10@gmail.com
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