Tall Indigo. Tall Indigo is the name we have given this Indigo, since it is so little known that most refer to it by its botanical name. Another plant that hasn't yet been spoiled with a common name. Just give it time, and we lazy Americans will think one up. Probably, "Tall Indigo" would do. This plant has to be one of my top 10 favorites. It will reach 8' plus and flower from late March to mid October. It works well mixed in the background of a perennial border, and it produces spikes of pink pea-like flowers at almost every node. The flower spikes are indeterminate, meaning that the first flower spikes which begin to form in March will still be extending and flowering in October. I have seen them over 24" long by the end of the season. Unbelievable!!! My description may seem somewhat stilted, but many of our customers have verified these same feelings. One will experience a bit of light suckering, which adds to its charm, giving it a more full appearance. It is the ultimate "see-through" shrub. Part to full sun.