Helianthus salicifolius (willowleaf sunflower, "Yanagibahimawari")

Japanese name: ヤナギバヒマワリ （柳葉向日葵）
Scientific name: Helianthus salicifolius

[Overview]
An evergreen perennial 1.5–2.5 m tall, growing in grasslands in its native range.
It spreads by extending underground stems.
The stem is erect, hard, whitish green and hairless.
Leaves are alternate, linear, up to 21 cm long and up to 1.2 cm wide, stalkless, and often hang down.
The leaf margin has very fine teeth or is entire.
The stem tips bear 6–15 flower heads 5–6 cm across.
The flower heads consist of ray florets and tubular florets; there are 10–20 yellow ray florets around the edge.
There are more than 50 dark brown tubular florets clustered in the center.
The fruit is an achene.

[Cultivation]
Propagate from seed or by division.
As long as the site is sunny and well drained, it grows well in most places, even if left alone.
For potted plants, water thoroughly when the soil surface dries; for plants in the ground, rainfall is sufficient.
Too much fertilizer makes it grow large and lush and fall over easily, so go light on fertilizer; for plants in the ground, basal fertilizer is enough and nothing more is particularly needed.
For potted plants, a small amount of slow-release fertilizer may be placed on the soil in spring and autumn, depending on how it is growing.
Set up stakes suited to its height to keep it from falling over.
Cutting it back hard around June allows it to flower at a lower height.
Cut it back to near ground level after flowering.
Pests and diseases include aphids, and powdery mildew may appear if ventilation is poor.

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