Perennial sunflowers

Christina Pax
Frederick County Master Gardener

Perennial sunflowers (Helianthus spp.), like their annual sunflower cousins, have a cheerful yellow bloom. They are typically smaller both in flower and stature, although some are still quite tall. They generally begin blooming in late August-September, then continue well into October and sometimes even November.

Finches and chickadees love seeds of perennial sunflowers. As a group, they prefer good, full sun and a moist, sandy soil and usually require some room, as they can become tall. They typically have both opposite leaves (on lower part of the stem) and alternate leaves (just below flower clusters).

Do perennial sunflowers always require full sun?

Helianthus decapetalus, thin-leaved sunflower or ten-petaled sunflower, blooms from July through October. It likes full or part sun, prefers sandy soil and grows from 2 to 5 feet tall, depending on circumstances. Helianthus divaricatus, or woodland sunflower, is a good sunflower candidate for less sunny locations, as its name implies. It prefers less moisture than other sunflowers, preferring dry to moist soil. Both are native to Maryland.

Is there a perennial sun-flower suitable for damp areas?

Helianthus angustifolius, swamp sunflower, has a pointy-petaled, yellow, daisy-like bloom with a dark center. This Maryland native blooms late August through October. Swamp sun-flower prefers moist, sandy soil of average fertility.

Butterflies visit these flowers, and if you let them go to seed, birds devour seed heads. Once established, a single clump can take command of 6 to 9 square feet of space in a garden, so plan accordingly! . Swamp sunflower typically grows 5-7 feet tall and is some-what vulnerable to slumping over during heavy rain, but if you cut it back in midsummer, you should be able to keep it more compact and eliminate any need for staking.

Is Helen's flower also considered a sunflower?

It's not a Helianthus by name, but Helen's flower, Helenium autumnale, is in the sun-flower family. Also (much less glamorously) referred to as common sneezeweed, it has anything-but-common wedge-shaped petals that are broadest at the tip. To add to the curiosity, each petal has three teeth at the tip, making it one of the most interesting textures found in a yellow, daisy-like flower.

Helen's flower is a Maryland native that blooms July

through November when it reaches a height of 3 to 5 feet. This one likes a damp spot in the garden and is an excellent candidate for a rain garden. It will tolerate drier soils, but will be shorter and more delicate.

I heard hummingbirds like red flowers. What can I plant for them that blooms later in summer?

For the deepest velvety-red color you can imagine, there is Lobelia cardinalis, cardinal flower. Although cardinal flower starts blooming already in July, its habit of opening up the flowers along its long stalk just a few at a time, from bottom to top, extends its bloom season long into October. This seems to suit the humming-birds just fine. They will some-times stake out a patch of cardinal flower and even fight over it because it provides nectar for such a long period of time.

Part sun is better than full sun for lobelias, as both leaves and blooms fade in full sun, and I have seen leaves burn where sun exposure is strong. In the wild, you might see this flower in small, damp clearings where a little patch of sun falls to the forest floor, often absolutely covered with swallowtail butterflies.

Although not as adaptable with sun requirements, cardinal lobelia will forgive a departure from its natural, very moist soil preferences, adapting fairly well to dry locations once established. Since it is a short-lived perennial, many gardeners mulch lightly if at all around cardinal flower to encourage its seeds to sprout and avoid covering over wintering crowns.

Will hummingbirds visit any other color?

Cardinal flower's close relative, great blue lobelia, Lobelia siphilitica, blooms well into fall and is also popular with hummingbirds. Great blue lobelia is native to Maryland's piedmont and mountain regions. It starts to bloom a little later than cardinal lobelia, usually in August. Both cardinal and great blue lobelia grow 2 to 5 feet tall.

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