It seems few members are quite interested in Strobilanthes cusia , as I did work with them for a few years, please allow me to share them a bit more here:)
Strobilanthes cusia which we also called Assam Indigo, in Chinese, 馬藍、大青, is one of the native Indigo we can find in Hong Kong, China.
They are being produced to Indigo (we called Hakka Blue 客家藍) by fermentation underwater（details will be talking in next post).
Assam Indigo is perennial, which they could harvest 2-3 times a year in May, August, and Late October, from our former experience, although plant once means harvest forever, we suggest replanting in max 6-7 years to ensure they are "young & fresh".
Our weather here in Hong Kong is range from 25-32°C in summer and could drop to 10-15°C in winter. They could be easily found in shade on the mountain near river, they love moist growing space. When they are planted at a good location, leaves size could as large as our palm, size will be shrink when in an unsuitable growing environment. Leaves colour will turn to yellow or yellowish green when too much sun. As being kind of herbs, they could easily plant to a height of 0.8-1m.
The best time for harvesting them will be the whole summer as once the temperature drop below 15°C in December, they start flowering, and colors will fade. Flowers color range from purple to pink and white. At late January, fruit could be seen, and turn from Green to Black once mature, 2-4 seeds could be found in the fruit.
In cultivation, they are possible to plant from seeds or cutting, but mostly we will be using cutting as it takes a shorter time.