The majesty of sunflowers

By Matt S., Pitt County Extension Director and Horticulture Agent
Nearly every gardener, young or old, has grown sunflowers at one point. There is something majestic about the size and color of sunflower in bloom that captivates those who love plants. And yet, it is sometimes difficult to find ways to incorporate sunflowers in traditional home gardens, for while a field of sunflowers on a farm can dazzle, a single stalk in the backyard may look lonely or out of place.
     The common sunflower, Helianthus annuus, is an annual flower that grows to heights of as much as 15 feet tall. If using them in the landscape, they fit best as a backdrop in mixed perennial or shrub borders. Since they cast a fair bit of shade due to their size, use smaller plants that can handle partial shade, but don’t require full shade, around their base. They can also be a good fit against fences, near walkways, in small masses, or as a border around a vegetable garden.

Left: Helianthus annuus, the common sunflower, grows up to 15 feet high. Right: Mexican sunflower, Tithonia rotundifolia, a cousin of the common sunflower.

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     There are many more options for those who love sunflowers than just the standard, tall, yellow-blooming annual. There are annual sunflowers both short and tall and in nearly every shade and combination of yellow, orange, red, bronze, and brown. There are sunflowers that are perennials, such as the swamp sunflower, Helianthus angustifolius. Finally, there are those plants that are essentially cousins of the common sunflower, such as Mexican sunflower, Tithonia rotundifolia.
     Some personal favorite annual sunflowers of mine include ‘Autumn Beauty,’ which has flowers that are red, bronze, and yellow, with many flowers having multiple colors on a single bloom, and ‘Strawberry Blonde,’ which has dark red centers and yellow-white tips. Both grow to about 6 feet tall, which is not short by any means, but a little easier to incorporate into a landscape than 15 foot tall varieties are. Dwarf varieties, like the red and yellow ‘Firecracker’, or the more traditional pure yellow ‘Zebulon,’ top out at about 3 feet.

Left: Swamp sunflower, a perennial with multiple flowers. Right: Strawberry blonde.

     While annual sunflowers typically have just a single flower per stem, the perennial swamp sunflower has hundreds of smaller flowers on each plant in fall. While it doesn’t make for as impressive a cut flower, the sight of a plant loaded with blooms is quite attractive, and blooms also come at a time of year when little else is in bloom other than perhaps mums and asters. Swamp sunflower is a prolific seeder and also spreads via underground stems called rhizomes (expect any plant with ‘swamp’ in the name to be fairly aggressive), so allow it plenty of space to multiply and be prepared to pull up plants that escape the boundaries you create. Swamp sunflower was chosen as the 2007 NC Wildflower of the Year by the UNC Botanical Garden.

Autumn Beauty pleases with its many shades of reds, bronzes, and yellows.

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     Mexican sunflower shares enough characteristics with annual sunflowers that they are botanically related, but differ enough that the average gardener would likely never connect them if not for the name. They do share a common flower shape, the daisy-like disk with a darkened center surrounded by lighter petals. However, Mexican sunflower produces many small tangerine-orange colored flowers on plants that grow from 2-4 feet high. Unlike the annual sunflower or swamp sunflower, both of which are tall slender stalks with little to no lateral growth, Mexican sunflower grows more like a small shrub, as wide, or wider, than it is tall.

Matthew Stevens is the County Extension Director and Horticulture Agent for North Carolina Cooperative Extension’s Pitt County Center.  If you have questions about this article or gardening in general, please contact the Pitt County Extension Master Gardeners at [email protected] or  252-902-1705.