Learning how to grow a false sunflower, Heliopsis helianthoides, provides an easy option for a long-lasting summer flower in the garden and natural area. Growing oxeye sunflowers is easy, you may already have them naturalizing in nearby wooded areas. Bright yellow blossoms appear in late spring and last until autumn frost takes them away.
I. Appearance and Characteristics
Heliopsis helianthoides is a species of flowering plant in the family Asteraceae, known by the common names rough oxeye, smooth oxeye and false sunflower. It is native to eastern and central North America from Saskatchewan east to Newfoundland and south as far as Texas, New Mexico, and Georgia.
Heliopsis helianthoides is a rhizomatous herbaceous perennial growing 40–150 cm (16–59 in) tall. The toothed leaf blades are oval to triangular or lance-shaped and may be smooth or hairy or rough in texture. The flowers are produced from midsummer to early autumn (fall). The inflorescence contains one to many composite flowerheads. Each head contains yellow ray florets which are generally 2–4 cm (3⁄4–1+1⁄2 in) long. The rays are fertile, having a small forked pistil at the base; this distinguishes them from true sunflowers. At the center are many yellow to brownish disc florets. The fruit is an achene about 5 mm (0.20 in) long.
In the wild, H. helianthoides may be found in wooded areas and tallgrass prairie, and sometimes along roadsides.
It is a popular garden plant for moist, fertile soil in full sun. Plants grow stiff and tall, so may require staking. Several cultivars are available with flowers of varying colors and shades. These include ‘Summer Sun’, ‘Golden Plume’, and ‘Prairie Sunset’.
II. How to Grow and Care
Sunlight
These plants prefer full sun to grow and bloom their best. They can tolerate light shade, though blooming might not be as vigorous and the stems might be floppy and require support. Plus, they can get leggy if they don’t get at least four to five hours of sun per day.
Temperature and Humidity
False sunflowers are cold-hardy perennials that will come back year after year in northern climates up to USDA growing zone 3. Some varieties also have good heat tolerance, making them ideal for the southern end of the plant’s growing zones. These plants also aren’t overly picky about humidity.
Watering
Although false sunflowers can tolerate drought, they do best with regular watering to keep the soil moderately moist. So if you’ve had a stretch without rainfall and the soil is dry, be sure to water your plants.
Soil
False sunflowers can thrive in a variety of soil types. They can even tolerate dry, poor, rocky, sandy, and clay soils. However, they prefer average, well-draining soil with a neutral soil pH for optimal growth.
Fertilizing
You likely won’t have to fertilize your plants unless you have very poor soil. Rich soil can cause a lot of leggy stem growth on false sunflowers. So go easy on the organic matter and fertilizer.
Pruning
False sunflowers do well when pruned. In the spring, to get those nice, fully formed plants, pinch the tips off the ends of the stems on the plant to encourage them to branch out. As false sunflowers bloom, deadhead any flowers that are spent, which will help stimulate new buds to form. If the plants start looking leggy or too tall, trim them back in the early summertime, which also helps produce new flowers. In mid fall, after the false sunflowers have stopped blooming, plan to prune the plants to about 2 inches tall. Pruning can also wait and be done in the early spring after any threat of frost is done.
Propagation
False sunflowers are clump-forming and tend to stay in one place, rather than spreading throughout the garden. Dividing your plants every two to three years will keep the clumps from dying in the center. You can do this in either the spring or fall. Here’s how:
- Select the plant to be divided and using a spade or shovel, dig up the plant making sure to dig deep enough not to disturb the root ball.
- Any dead, mushy, or broken roots should be cut off the root ball with pruning shears before separating the plant.
- Using a sharp knife cut the plant apart in half or thirds.
- Plant the divided plants immediately in a prepared suitable location and water the soil till moist but not overwet.
How to Grow from Seed
You can start false sunflowers by seed in either the spring or fall. For spring, start seeds indoors four to six weeks before your last frost date. In the fall, direct sow in mid-to-late August. Keep the growing medium moist but not overwet. If started indoors, the seedlings can be planted outside once any danger of frost has passed. Make sure to harden off seedlings before planting outside. Sowing directly into the garden will require being planted in moist but well-drained soil and covering with about 1/8 inch of dirt. Water and plan to thin the seedlings as needed. Plants should be spaced 18-24 inches apart.
As perennials, false sunflowers tend to begin blooming in their second year, so a spring seedling might not flower the year it’s planted. However, seeds started in the fall should provide blooms the following summer.
Potting and Repotting
Since false sunflowers grow in clumps, they work well for putting in pots or container beds with other flowers. Place them in a container with potting soil, making sure to plant to the same depth, not covering up the base of the plant. Full sun and plenty of water will keep these adorning your patio or lanai, creating a colorful and beautiful arrangement.
Overwintering
False sunflowers that are planted in the ground can be left untrimmed until spring. The dead leaves and stems will help to protect the roots and base of the plant, plus wild birds will feed on any remaining seeds. Plants that are in containers can be brought into a garage area or placed in a protected location and elevated to avoid ground frost.
How to Get to Bloom
These bright, cheery flowers love to bloom and will start flowering in early July and go through August. To keep false sunflowers blooming longer, simply take off any flowers that are done blooming by deadheading them. This process not only keeps the plants looking fresh and neat, but also encourages more flowers. Trimming the plants if they get too tall or look scraggly will also encourage further flowering.
Pests and Diseases
In general, false sunflowers don’t have any serious pest or disease issues. But aphids can be a problem for the plants, as can powdery mildew. With aphids, you might notice crumpled or otherwise damaged foliage. And with powdery mildew, you’ll see splotches of white or gray on the leaves and stems. Providing good air circulation for your plants can help to prevent and mitigate both of these issues before you turn to insecticides or fungicides. A strong spray of water may remove aphids.
III. Uses and Benefits
The natural habitat of False Sunflower is prairies, meadows, and roadside ditches. Thus it is right at home in a micro-prairie, a border garden, or anywhere that you allow plants to get a little ‘wild’.
It can be used in formal flower beds, but you will need to take some action to stop it from flopping/leaning. Planted in isolation often results in all stalks leaning away from the plant. They won’t touch the ground, but they will easily lean at 50% the height of the plant.
IV. Harvesting and Storage
Seed can easily be saved from False Sunflower in the same manner one saves seed from Echinacea. Simply collect the dried seed heads in a brown paper bag, and then store them for one week in a cool dry place (like your garage) to completely dry.
Then, place the seed heads in a container with a lid, and shake them up. As the seed heads hit the sides of the container the seed is released (with a small amount of chaff).
Fully dried seed can be stored in a zip-lock bag in a dark place for several years.
Find Where to Buy the Best False Sunflower (Heliopsis helianthoides)
[content-egg-block template=offers_logo_shipping cols_order=3,2,1,5,4 hide=badge visible=number border_color=info limit=8]