The false sunflower with its flowers provides warm yellow tones in the garden until well into autumn. The perennial is pleasingly easy to plant and care for.
Profile of false sunflower:
Scientific name: Heliopsis helianthoides
Plant family: daisy family (Asteraceae)
Other names: smooth oxeye, rough oxeye
Sowing time: March to August
Planting time: spring and autumn
Flowering period: July to October
Location: sunny to partially shady
Soil quality: gravelly to loamy, lime tolerant, moderately nutritious, humus rich
These information are for temperate climate!
Use in: flowerbeds, flower bouquets, group planting, borders, cottage garden, flower garden, natural garden
Winter hardiness: hardy, USDA Plant Hardiness Zones: 4 (-32 °C / -25 °F)
Bee and insect friendly: Yes
Plant characteristics and classification of false sunflower
Plant order, origin and occurrence of false sunflower
The false sunflower (Heliopsis helianthoides) is a perennial from the daisy family (Asteraceae). Its natural range extends from parts of North America down to Mexico. It is a hardy and wonderfully undemanding garden plant, which flowers from summer to autumn with a lot of flowers. It is also known as smooth oxeye and rough oxeye.
Characteristics of false sunflower
Depending on the variety, the clump-forming perennial grows between 60 and 170 centimeters (24 to 68 in) high. Since the plant grows very upright, the width is only about 60 to 80 centimeters (24 to 32 in). The leaves and usually also the loosely branched stems are bristly hairy, the habitus bushy and loose.
The leaves of the false sunflower are deep green to dark green and hairy on both sides. They are oppositely arranged, lanceolate and tapered at the front. The leaf edge is usually serrated.
The false sunflower is a true beautiness during the flowering period, which can last from July to October. Then many simple, semi-double or double ray-shaped flowers adorn the perennial. Heliopsis helianthoides flowers in different shades of yellow.
In the late autumn, the smooth oxeye develops so-called achenes, inconspicuous lonely indehiscent fruits with pappus.
False sunflower – cultivation and care
The false sunflower feels most comfortable in a bed in a full sunny position. However, light partially shady areas are also tolerated. The species grows in its original distribution area on dry and warm slopes or on humid meadows.
A nutrient-rich substrate provides ideal growth conditions for the false sunflower. Although the plants grow naturally on dry soils, they prefer fresh to moist conditions. Alkaline or slightly acidic soils are tolerated by the plant. They grow on normal garden soil as well as on stony, sandy or clayey soils. The substrate should have a high permeability, because the roots cannot tolerate waterlogging.
Planting false sunflower
You can plant smooth oxeye in the bed between spring and autumn. As the plants develop dense clumps over time, you should ensure sufficient distance when planting. One square meter (10 sq ft) provides space for between four and six plants. A distance of 45 centimeters (18 in) between plants is ideal. The planting distance should be based on the expected growth width. The minimum distance should correspond to half the height of the plant.
Preparations for planting:
- Loosen the soil and remove old plant parts
- Improve very sandy soils with compost
- Mix heavy clay soils with sand
Smaller varieties are suitable for planting in tubs. In order to cultivate high growing false sunflowers in a plant pot, you need sufficient space. Plant false sunflowers in deep clay pots that have been equipped with drainage. Drainage holes prevent waterlogging in the bottom of the pot. Place the pot in a sunny and wind-protected place so that the high stems bloom splendidly and do not bend. Bamboo sticks will do great as support.
Heliopsis species are drought tolerant. Fresh conditions ensure healthy and vigorous growth, so you should water the plant regularly during long dry periods. As soon as the top layer of soil has dried out, the next watering should be done. You can mulch the soil to protect it from excessive dehydration.
The nutritional requirements of false sunflowers are moderate. If the soil is humus, you only need to fertilize a little. Add compost to the soil when planting out. This measure can be repeated every year in spring. The plants consume nutrients throughout the summer, so no additional fertilization is necessary.
If the plants grow in pots or on poor soil, they will enjoy a regular supply of organic-mineral fertilizers. Give the plants liquid fertilizers in low concentrations (a swill made of compost is also suitable) in spring and shortly before flowering. An overdose will cause the perennials to develop long shoots and lots of leaves but no flowers.
Cut faded stems regularly to encourage the growth of new flowers. In this way you can extend the flowering period until the first night frosts occur. If necessary, radical pruning can be done in spring before new shoots appear, when the perennial looks unsightly and grows sparse.
Cut back the stems to a hand’s width above the ground. The plant will then sprout again and form denser branches. Once the false sunflower has developed leaves, it should not be pruned back. Pruning in the autumn means that the plant can no longer store sufficient energy in the rhizome.
In spring or autumn you can divide the rootstock of the perennial.
If older perennials become lazy in flower or grow too densely, the stands can be rejuvenated and thinned out by division. This measure is also suitable for propagation and can be done every two to three years in spring.
Dig out the root ball and divide the rhizome into several pieces with a spade. Dead roots are removed before the partial plants are placed in the prepared planting hole. After transplanting, water thoroughly and mulch the soil. In the following two weeks the plants need a lot of water.
The seeds are grown on nutrient-poor soil six weeks before planting. As substrate, you can use cactus soil or coconut fibres. The seeds are sown from the end of March or the beginning of August and pressed lightly. Ideal germination conditions are found in the mini-greenhouse, where temperature and humidity are high.
When the seedlings are 3 to 4 cm (1.2 to 1.6 in) high, they are separated into pots and gradually acclimatized to the outside temperatures. Then the young plants can be put outdoors. If they are planted in autumn, the plants will develop flowers for the first time in the second year.
Diseases and pests
False sunflowers are robust against diseases or pests. Pest infestation rarely occurs if the plants grow in suboptimal locations or are weakened by incorrect care measures.
Sick and weakened plants are occasionally attacked by aphids, which spread out en masse in spring. Remove the pests with a cloth and spray the plant with an oily solution. Ensure good ventilation after treatment.
In spring the freshly sprouting leaves and shoots are a source of food for snails. Spread pebbles or coffee grounds on the substrate.
Sun-eyes prove to be frost hardy plants that do not need winter protection. Potted plants should be protected accordingly from ground frost. The substrate freezes faster in the pot than in the bed. Overwinter the pots in a protected location near a south-facing house wall. Make sure that no rainwater or snow accumulates in the pot and lift the pot away from the ground on a wooden block.
Use in the garden
The loosely bushy to narrow habit makes the false sunflower the perfect plant for small beds. It requires little space and prefers a location in the foreground of perennial plantings. Place the plant in small groups to intensify the aesthetic effect. The flowering plant decorates beds, borders and flower meadows.
In addition to high flame flower, medium-high grasses and asters, the smooth oxeye will be shown to its best advantage. You can plant Heliopsis species to shade low growing perennials that prefer partially shady conditions. The late flowering period makes the plant an important source of nectar and pollen in late summer and autumn. The flower stems are suitable as cut flowers for bouquets and vases.
False sunflowers are suitable for wild nature gardens, species-rich cottage gardens, colorful flower gardens and sandy rockeries.
There are many varieties of the false sunflower available in stores. ‘Benzinggold’ grows to a height of 120 centimeters (48 in) and has simple, orange-yellow flowers. ‘Goldgrünherz’ grows slightly higher at 150 centimeters (60 in) and has striking, fully double yellow flowers with a green center. ‘Asahi’ has very beautiful, double flowers. The variety name comes from the Japanese and means “morning sun” – exactly this orange-yellow color is also used for the flowers. ‘Hohlspiegel’ has dark foliage, semi-double orange flowers and grows 130 centimeters (52 in) high. Recommended varieties for cut flowers are ‘Venus’ and ‘Karat’, which both have single yellow flowers. Experience shows that false sunflowers with single flowers in the vase last longer than those with double flowers.