Calendula arvensis (field marigold, "Himekinsenka")

Japanese name: ヒメキンセンカ （姫金盞花）
Scientific name: Calendula arvensis

[Overview]
An annual or biennial 10–50 cm tall.
The stems and leaves bear many somewhat sticky, soft glandular hairs.
The stems are much branched, spread somewhat creeping along the ground, and are ridged.
The leaves are alternate, elliptic, about 3–8 cm long and 1.5–2 cm wide, with entire to slightly toothed margins.
A single flower head 1.5–2 cm across is borne at the tip of the flower stalk; the ray florets are orange-yellow and the tubular florets are bright yellow.
The involucral bracts are 0.5–1 cm long and have glandular hairs.
The flowers open during the day and close at night.
The fruit is an achene without a pappus, strongly curved like the letter C, with many projections on the dorsal side.

[History]
It is said to have arrived in Japan in 1597.

[Cultivation]
Propagate from seed.
It is easy to grow.
It prefers a sunny site with good drainage and good water retention.
With poor sunlight, flowering is poor.
It grows poorly in acidic soil and prefers slightly alkaline soil.
It is cold-tolerant, but frost and snow damage the leaves, so frost protection may be given.
Water thoroughly when the soil surface dries.
Fertilizer is hardly necessary if basal fertilizer has been applied.
Setting seed tires the plant, so pick off flowers promptly after they bloom.
Pests and diseases include powdery mildew, cutworms and aphids.

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