Thunbergia grandiflora (blue trumpet vine)

Japanese name: ベンガルヤハズカズラ
Scientific name: Thunbergia grandiflora

[Overview]
In its native habitat it is an evergreen climbing perennial growing over 10 m tall, but it is sensitive to cold and is often treated as an annual in cold regions.
The stem has four ridges and is hairy, and the base becomes woody.
The leaves are simple and opposite, 5–20 cm long and 4–15 cm wide, broadly lanceolate to angular heart-shaped; the shape, the presence of hairs and the toothing vary greatly.
The leaf base is heart-shaped, with 3–7 palmate veins.
The leaf margins are toothed or entire.
There is a leaf stalk.
In the tropics it flowers all year round, but in Japan it flowers mainly from summer to early autumn.
The flowers are borne singly in the leaf axils, or 2–4 at each node of a raceme.
The flowers are funnel-shaped, 5–8 cm across, with 5 lobes at the tip, and the flower tube is about 4 cm long.
The flower color is bluish purple with a range of shades, and the inside of the flower tube is yellow.
The fruit is a capsule.

[Cultivation]
Propagate by cuttings.
It prefers fertile, sunny, well-drained soil.
It is safest to keep it at 10°C or higher for overwintering; for plants in the ground in areas without frost, cutting them back hard to near the base and mulching the base with straw or similar makes overwintering easier.
In cold regions, grow it as an annual, or grow it in a pot and bring it indoors in winter to a sunny, warm place, watering minimally to overwinter it.
For potted plants, from spring to autumn water thoroughly when the soil surface dries, and keep them on the dry side in winter; for established plants in the ground, rainfall is sufficient unless summer brings a long spell of sunny weather and the soil becomes dry.
From spring to autumn, apply slow-release chemical fertilizer placed on the soil.
Pests and diseases include scale insects, spider mites, aphids and whiteflies.

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