Note:
(a) "Various plant species can produce natural indigo dye, but 'Persicaria tinctoria,' also known as Chinese or Japanese indigo, is a favorite among Southern Californians who like to grow their own for dyeing."
(i) Persicaria tinctoria 蓼藍 (cn.wikipedia.org: 亦略稱為藍或靛青)
en.wikipedia.org/wiki/Persicaria_tinctoria
("The leaves were a source of indigo dye. It was already in use in the Western Zhou period (ca 1045-771 BC), and was the most important blue dye in East Asia until the arrival of Indigofera [a genus 'widely distributed throughout the tropical and subtropical regions of the world] from the south")
(ii) More photos of Persicaria tinctoria:
龍 (name of the author), 藍（アイ）. 花図鑑 (pronounced "hana-zukan" where "hana" is Japanese pronunciation and "zukan" Chinese pronunciation), Oct 5, 2011.
hana-zukan.net/161sakumotu.html
(A) アイ is katakana, pronounced “ai”--the same as 愛. That is why (c) calls it color of “love.”
(B) 花図鑑 is in Japan pronounced "hana-zukan" where "hana" is Japanese pronunciation and "zukan" Chinese pronunciation)
(b) artist-entrepreneur Graham Keegan "is giving away 2-inch-high seedlings at his Silver Lake studio"
Silver Lake, Los Angeles
en.wikipedia.org/wiki/Silver_Lake,_Los_Angeles
(built around a city reservoir which gives the district its name)
(c) “Keegan likes to use indigo in Japanese shibori tie-dye, a style that dates from the eighth century based almost entirely on this plant species, brought from China a century earlier. It has a unique shade, called aio-iru in Japanese -- color of love.”
(i) shibori 絞り(P); 搾り 【しぼり】 (n): “(1) tye-dye; tye-dyeing * * * (3) contraction; squeezing; choke”
(ii) The spelling is wrong! It should be “aoi iro” 靑い色色.
(A) aoi 靑い 【あおい】 (adj): blue, green”
(B) iro 色 【いろ】 (n): “color”