Several years ago, we sowed Indian indigo seeds—each no larger than the tip of a pen—in a planter. That first attempt is described in our Japanese-language article Growing Indian indigo.
This article follows the plants as they flowered, produced seed, survived the winter and finally reached their first harvest. We then began making precipitated indigo, also known as indigo paste, from the harvested leaves.
Growing Indian indigo from tiny seeds
▼ Indian indigo seeds as small as a pen tip
The cultivation began with very small seeds sown in a planter.
Before long, the seedlings opened their first leaves. We expected them to grow steadily, but at the time we could not find detailed cultivation guidance suited to Japan, and there were moments when the plants seemed close to dying.
▼ Indian indigo seedlings opening their first leaves
Flowering and producing seed in summer
Although their growth was uncertain for a time, the plants eventually recovered. They flowered in summer and later produced many seeds.
One of the best-known plants referred to as Indian indigo is Indigofera tinctoria, a member of the pea family. Its characteristics and historical use as a source of natural indigo are introduced by the Royal Botanic Gardens, Kew, on its official True indigo page.
▼ Indian indigo flowering in summer
Surviving winter after losing the leaves
Indian indigo is a plant of warm regions. Even after the pots were moved indoors for winter, the leaves fell one after another and the plants appeared to be dying.
We thought they might not recover, but when temperatures rose the following spring, new shoots emerged from three remaining plants. They had apparently survived the winter.
During the summer, the branches and leaves developed strongly, and the plants grew considerably larger than in the previous year.
The first harvest after overwintering
When the heat began to ease, we cut back the plants and harvested Indian indigo for the first time.
▼ Indian indigo grown large after surviving winter
▼ Indian indigo harvested for making indigo paste
Beginning to make precipitated indigo
Using the harvested plants, we began making precipitated indigo. The blue material stored in a wet, paste-like state is often called indigo paste or mud indigo.
This was our first attempt to make precipitated indigo from Indian indigo.
We did not yet know whether the same method used each year for Japanese indigo would work, or whether differences between the plants would change the fermentation and settling process.
The basic method using Japanese indigo is explained in our Japanese-language article How to make precipitated indigo, indigo paste and dried indigo cakes.
There was some uncertainty, but we continued while observing the condition of the Indian indigo. We planned to report later on the resulting paste and whether it could be used successfully for dyeing.