Growing & dyeing with

FRESH INDIGO

If you’ve found your way to this page, it may be because you purchased indigo seeds from my shop — thank you!

The seeds I share come from Japanese indigo (Persicaria tinctoria) plants grown organically and with great love & care in my garden. I grew them in two seven-gallon terracotta pots last spring, feeding them with seaweed dashi and fresh compost. The plants contained in just these two relatively small containers produced over two-thousand seeds this past season! This is more than I could ever use, so I opted to share them with you.

Persicaria tinctoria is native to Southeast Asia, particularly Japan, where the plant is called tadei. The seeds I offer are specifically the Ko-sen-bon variety, differentiated by their bright, nearly neon pink-colored flowers and broad leaves. The leaves contain high quantities of indigotin — indigo’s famous blue dye in its purest form — which make Japanese indigo a choice dye plant for growing and creating with.

Continue reading below for growing tips and fresh- & dried leaf dye projects (coming soon).

*Flowering Japanese indigo with tiny black seeds beginning to show.*

Growing Persicaria tinctoria

Japanese indigo seeds lose viability after a year, so plan to sow in spring 2022 if you purchased seeds from my shop.
Indigo is intolerant of frost, requiring warm days, plenty of sun, and moist, fertile soil to thrive.
In warmer climates, sow seeds directly in the earth (or pot) once the last cold days have passed. (Here in Altadena, CA — zone 10 — I sow my seeds outdoors when the days are growing warm, around late March.)
In colder climates, you can start indigo seeds inside ~6 weeks before the last frost, transplanting them in the ground when it’s warm enough and there’s no further chance of frost. (Or simply wait until the last frost has passed, and sow directly in earth or pot.)
Optional: soak seeds in water overnight before sowing for quicker germination. (Un-soaked seeds take up to 60 days to germinate.)
Plant seeds 1/4” deep, tamping soil securely on top. Seeds can be broadcast, or individual starts can be planted 6 inches or so apart.
Keep soil moist until plant matures, switching from daily watering in spring to deep, weekly watering in summer.
Indigo grows quickly in late spring and early summer, maturing at ~150 days.
Harvest the leaves for dye throughout the summer and fall (see more below).

*Young Japanese indigo plant visited by a jumping spider.*

Caring for & harvesting Persicaria tinctoria

Mature Japanese indigo plants reach ~3 feet tall. I recommend pinching off the tops of the plant at a growth node when they reach about 12 inches tall, as this will promote bushier growth — meaning more leaves for dyeing!
Harvest throughout summer and fall, pruning at growth nodes to ensure healthy regrowth. Some dyers choose to harvest down to a couple growth nodes from the ground, producing 2-3 major harvests per year; others choose to trim approx. the top 4 inches of the plant more frequently, allowing for many harvests throughout the season.
The indigotin (pure blue dye) is found solely in the leaves. The first harvest of leaves will likely have the most indigotin and therefore the strongest color. Harvest in mid-morning once any dew has evaporated, but before the plant has had a chance to dry out in the midday sun.
Fresh leaves must be used within a couple hours of being harvested, so plan to trim and dye the same day — ideally the same morning.
Dried leaves can be saved and extracted for dye in a fermenting (vatting) process. Dyeing with the fresh leaves is easier and faster, but you can also save your dried leaves for dyeing another day.
Indigo is an annual, so they’ll need to be replanted each year. They produce abundant seeds, and in climates that don’t experience frost, you can let them re-seed themselves.
Note: Japanese indigo’s leaves are green when fresh, but turn blue when dried (due to oxygenation of the indigotin).

Dyeing with Persicaria tinctoria

When dyeing with indigo or other natural dyes, use only natural fabrics (cotton, linen, hemp, bamboo, silk, wool, etc.).
One of the best parts about dyeing with indigo — either fresh or vatted — is that it requires no mordanting (pre-treatment) of fabric!
If you’re working with a newer textile, a good scouring is always recommended. (See instructions for that process here.)
- Scouring removes contaminants & sizing left over from the textile milling process, and is an essential process to ensure fabric and dye form an even and permanent bond. Vintage or otherwise well-worn fabrics may not require scouring.

Fresh leaf indigo projects coming soon

I’ll be sharing dye projects utilizing indigo’s fresh leaves starting this spring! Focusing on projects accessible to first-time dyers and growers, I’ll share with you how to utilize indigo’s mesmerizing blue dye using a modest quantity of leaves that can be gathered from just one or two plants. I hope you’ll check back soon to grow and dye along with me!