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Sunflowers - Growing a Banner of Summer, the Sunflower

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Sunflowers aren't just yellow anymore.

Sunflowers aren't just yellow anymore.

Photo: © Marie Iannotti (2007) licensed to About.com, Inc.

Overview:

Sunflowers are native to North America, but they are very often associated with the Mediterranean area. The flowers have a wide central disk surrounded by shorter petals in shades of cream, yellow, rust and burgundy. The sturdy stems can grow 10 feet or more and may hold single flowers or be multi-branched. The seeds are edible and are favored by birds. They are also used to make oil and as livestock feed.

Latin Name:

Helianthus

Common Name: Sunflower

USDA Hardiness Zone:

Annuals

Exposure:

Full Sun

Bloom Period:

Mid to Late Summer

Description:

There's a reason they're called sunflowers. The flower heads follow the sun. So give some thought to where you plant your sunflowers. If you plant them on an east/west axis, you will be looking at the back of the flower heads for most of the day.

Traditionally, sunflowers where a sunny yellow color with a darker central disk. However now we have a choice of rich chocolate browns, deep burgundies and luscious multi-colored flowers.

Design Suggestions:

Be careful when growing the taller varieties because they can easily shade other plants. Tall sunflowers work best as a screen or in the back of a border. They're also great for growing vines on. Shorter dwarf varieties can more be easily worked into a garden border. If you are growing sunflowers for cutting, choose a multi-branched variety to get the most blooms. Which ever variety, plant in clusters of at least 9 plants, for the best impact.

Suggested Varieties:

Wonderful new varieties come out every year. Here are a few standouts:
  • 'Russian Giant' - A single yellow flower that can be 20" across. Great for seeds (10 - 12')

  • 'Teddy Bear' - a great dwarf variety with a fluffy flower head. Nice for containers. (1-2') 'Giant Sungold' is a 5' version of 'Teddy bear'.

  • 'Autumn Mix' - Tall growers that give you a rainbow of fall colors on large flower heads. (6' +)

  • 'Italian White' - Creamy white flowers with great seeds for the bird feeder. (4')

  • Prado Series - Shades of burgundy. Multi-flowered and early blooming. Great for cutting.

Pests & Problems::

  • Birds & Squirrels - Use frightening devices or cover the heads with netting.
  • Sunflower Moth -Lays its eggs on the plant and the larvae feed on the flower heads, tunneling and leaving holes in the seed.
  • Aphids and Whiteflies can also be pests, but what don't they like?
  • Fungal Diseases: Sclerotina (White Mold), Downy Mildow, Rust - Provide adequate air circulation.
  • Verticillium Wilt - You'll see dead areas inbetween the leaf veins, with yellowish margins. Choose resistant varieties.

The best control of diseases is prevention, by changing where you plant each year and disposing of any infected plants. And if you're worried about squirrels or other animals getting the seeds before you, try growing them in the vegetable garden. Flowers in the vegetable garden are great for attracting more pollinators. To further foil squirrels, plant a coarse leaved vegetable, like squash, at their base.

Growing Notes:

Sunflowers can be direct seeded in the garden, once all danger of frost is past, or they can be started indoors 3-4 weeks before transplanting. Peat pots are recommenced for seedlings started indoors, because sunflowers don't like to have their roots disturbed. Transplants often grow faster and flower sooner than direct seeded plants, so you could lengthen your bloom period by doing both.

Plant seeds 1-3 inches deep and 6-12" apart. Taller varieties should be thinned to about 1 - ½' apart. Dwarf varieties can be planted about 1' apart. Birds and other animals are attracted to sunflower seedlings, so some protection when they are young is suggested. Cover them with row covers or screening and remove when plants are a foot or two high.

Sunflowers like a well-drained soil with a good amount of organic matter. They are extremely fast growers and appreciate a fertilizer high in phosphorous and potassium, (the middle and end numbers on the fertilizer package), to remind them they're supposed to set flowers on those tall stalks.

Maintenance

  • Watering regularly will help them set flowers. They will stop blooming during periods of drought.

  • Sunflowers do not like to compete with weeds. Mulching will help with both soil moisture and weed suppression. And don't forget that sunflowers need a lot of sun.

  • Most sunflowers get top heavy when they bloom and can use the support of staking. If they are planted very close together, they may support themselves, but usually a heavy rain or strong wind will cause them to lean and they won't straighten up on their own. Planting sunflowers along a fence is the easiest way to stake them. Bamboo stakes are also strong enough to keep the upright. Use care when inserting the stakes, so you don't damage the sunflower roots.

Harvesting

Flowers should begin to mature in early fall. The heads will turn downward and the florets in the center disk will shrivel. The only sure way to tell if the seeds are ready to harvest is to pull a few out and open them. If they are full, they're ready. To harvest, cut the hole flower head with about 1' of stem attached and hang in a warm, dry, ventilated spot, away from insects and rodents. Cover the seed heads with cheesecloth or a paper bag, to catch loose seeds. Poke some small holes in the paper bag for ventilation. When the seed is completely dried and ready for use, it can be easily rubbed off the flower head and collected.

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