Indigo Dyeing Guide – Dyeing with Indigo Plants Many of us have bought one of these dye packs at the supermarket. Whether you want to brighten up an old pair of jeans or create a new color on a neutral fabric, dyes are easy and useful products. But what if you want to make your own plant-based dye  and bypass all those chemicals? Dying with indigo allows you to ensure that the dye is non-toxic and allows you to observe a fascinating chemical process when a green plant turns blue. Continue on to learn how to dye with indigo plants.
About the plant dye indigo
Dyeing with indigo has been around for thousands of years. Making indigo plant dye requires a fermentation process that creates a magical color change. The primary plants used to make indigo are woad  and Japanese indigo  , but there are a few lesser-known sources. Whatever plant you purchase, there are numerous steps to making the dye.
Indigo is said to be the oldest dye, with fabric the shade found in Egyptian pyramids. Ancient civilizations used indigo as more than just a fabric dye. They used it in cosmetics, paints, crayons, and more. It takes at least 100 pounds (45 kg) to make 4 ounces (113 g) of dye. This made it a very valuable commodity. The process includes 6 steps: fermentation, alkalinization, aeration, concentration, straining and storage.
The initial process must be carried out without the presence of oxygen, which causes the blue color to arrive too early. It is also necessary to have fairly warm temperatures to promote the fermentation process.
Making indigo vegetable dye
First you need to collect lots of indigo producing plants. Once you have lots of cut stems, pack them tightly into a dark plastic tub. Add water to cover the stems and weigh them down with a net covered with rocks.
Cover the tub and allow fermentation to occur over 3 to 5 days. After the time has elapsed, remove stems and leaves.
Next, add 1 teaspoon (3.5 g) per gallon (4 L) of slaked lime. This makes the solution alkaline. Then you need to whip out the infant dye. It will become foamy and then blue, but it won’t be done until it’s an ugly, reddish-brown hue. Then settle the sediment and skim the concentrate off the top.
Strain several times and it’s ready for immediate indigo dyeing or storage in glass bottles for a year. You can also dry the pigment and it will last indefinitely.
How to Dye with Indigo Plants
Once you have your pigment, dyeing with indigo is straightforward. You can create patterns by adding something that resists the dye, such as: B. String (binding dye), wax or other items that prevent dyes from coloring the fabric.
The dye is prepared by mixing:
0.35 ounces (10 grams) indigo
0.71 ounces (20 grams) soda ash
1 ounce (30 grams) sodium hydrosulfite
1.3 gallons (5 liters) of water
2 pounds (1 kg) of fabric or yarn
You need to slowly temper the soda and indigo dye with water so that it is liquid enough to add to the vat. Bring the remaining water to the boil and slowly stir in the other ingredients. Use metal tools and gloves when dipping your fabric. Repeated immersion results in darker blue tones.
Allow the garment to dry. The blue tones created by indigo plant dye are unique and much more environmentally friendly than synthetic dyes.
Dye from Indigo Plants: Learn about making indigo dye
The blue jeans you wear today are probably dyed with a synthetic dye, but that wasn’t always the case. Unlike other colors, which were easily obtained from bark, berries, and the like, blue remained a difficult color to recreate—until it was discovered that dyes could be made from indigo plants. However, making indigo dye is not an easy task. Dying with indigo is a multi-step, labor-intensive process. So, how do you make indigo vegetable dye? Let’s find out more.
About the plant dye indigo
The process of turning green leaves into bright blue color through fermentation has been passed down for thousands of years. Most cultures have their own recipes and techniques, often accompanied by spiritual rites, for producing natural indigo dye.
The birthplace of dyes from indigo plants is India, where the dye paste is dried into cakes to facilitate transportation and sale. During the Industrial Revolution, on-demand indigo dyeing reached its peak due to the popularity of Levi Strauss’ blue denim jeans. Since indigo dye costs a lot to make, and I mean A LOT of sheets, demand began to outstrip supply and so an alternative was sought.
In 1883, Adolf von Baeyer (yes, the aspirin guy) began studying the chemical structure of indigo. Over the course of his experiments, he found that he could recreate the color synthetically and the rest is history. In 1905, Baeyer received the Nobel Prize for his discovery and blue jeans were saved from extinction.
How do you make dye with indigo?
To make indigo dye, you need leaves of various plant species such as indigo  , woad  and polygonum  . The dye in the leaves doesn’t really exist until it’s manipulated. The chemical responsible for the dye is called an indicator. The ancient practice of extracting indicant and converting it into indigo involves fermenting the leaves.
First, a series of tanks are built in stages from highest to lowest. In the highest tank, the fresh leaves are placed along with an enzyme called indimulsin, which breaks down the indicator into indoxyl and glucose. During the process, carbon dioxide is released and the contents of the tank turn a dirty yellow color.
The first round of fermentation lasts about 14 hours, after which the liquid is drained into the second tank, one level lower than the first. The resulting mixture is stirred with paddles to incorporate air, allowing the brew to oxidize the indoxyl to indigotin. When the indigotine settles to the bottom of the second tank, the liquid is sucked out. The settled indigotine is transferred to another tank, the third tank, and heated to stop the fermentation process. The end result is filtered to remove impurities and then dried to form a thick paste.
This is the method that Native Americans have used to extract indigo for thousands of years. The Japanese have a different process that extracts indigo from the Polygonum plant. The extraction is then mixed with limestone powder, lye ash, wheat husk powder and of course sake, because what else would you use it for other than dyeing, right? The resulting mixture is allowed to ferment for about a week to form a pigment called sukumo.
Indigo Plant Pruning – How To Prune Indigo Plants In The Garden
Growing indigo is not difficult as long as you can provide adequate sunlight and heat. However, regular pruning of true indigo keeps the plant healthy and attractive. Indigo  is particularly attractive when trained against a sunny wall and tends to grow slightly larger. Read on and we’ll cover pruning and pruning indigo plants.
Cut back indigo
Indigo ( Indigofera tinctoria ) is an ancient plant famous for the intense blue dye extracted from the leaves. Although most clothing manufacturers have switched to chemical dyes, true indigo dye is still preferred by people who prefer to work with natural dyes  – especially manufacturers of premium denim.
Indigo is a beautiful, arching plant that shoots from the base and produces masses of purple or pink flowers that burst forth in summer and early fall. Indigo is a hardy plant suitable for growing in USDA plant hardiness zones 3 through 10.
Not only does cutting the plant back keep it healthy and manageable, but cutting the plant  back a few inches (7.5-10 cm) from the ground is a common method of harvesting the foliage for those who grow their own want to produce color.
How to Prune Indigo Plants
Pruning true indigo should be done in spring if you live in a frost-prone area. Cut off all of the previous year’s growth at ground level. Be sure to remove winter-damaged vegetation.
If you live in a warmer climate, reducing indigo may be a little less drastic. Simply shorten the plant by up to half its height to maintain the desired size and shape. Pruning also prevents the plant, which can reach heights and widths of 3 to 4 feet (1 m), from growing too large.
Regularly remove dead flowers and yellowed leaves during the summer to keep the plant looking its best.
Cutting back the plant to harvest the leaves can be done as needed throughout the growing season. The plants usually grow back quickly for another round of harvest within a month or so.
Indigo Seed Planting Guide: When to Sow Indigo Seeds
The indigo plant has been used for thousands of years to produce the beautiful color of the same name. The leaves can color the fabric a rich bluish-purple. True indigo is Indigofera tinctoria and can be successfully grown from seed for a pretty flowering shrub or to provide you with leaves to make a natural blue dye.
How to Plant Indigo Seeds
Indigo is a member of the legume family  , so growing it in your garden has the added benefit of adding more nitrogen to the soil. The shrub-like plant grows up to 2 m tall and produces pretty pink to blue flowers. Whether it grows as an annual or perennial depends on the climate. It grows best in zones 9 and warmer, but in colder climates it grows as an annual.
Growing indigo from seeds is not difficult, but it does require warmth. Unless you are in a warm climate, you will need a greenhouse. a warm, sunny windowsill; or even a heated greenhouse for the best results.
Start propagating your indigo seeds by soaking the seeds in water overnight  . Plant the seeds in individual pots that are 3 to 4 inches in diameter. The roots don’t like to be disturbed, so you won’t have to disturb them as often if you start them in larger pots instead of trays.
Repot the seedlings once or twice, finally using a 2.5 gallon (10 L) pot for final planting unless planted directly outdoors.
Make sure to fertilize your growing indigo plants regularly as they require a decent amount of fertilizer  . They also need moisture, so mist them regularly.
When to Sow Indigo Seeds
As long as you have enough warmth for the seeds, planting indigo seeds should be done as early in the season as possible. This gives you a longer growing season and plenty of time to develop leaves if you want to make dyes.
Sow the seeds any time between early February and around mid-April. If you are growing the indigo for dyeing and want to grow the plant as a perennial, be sure to harvest only half of the leaves per season.
The right time to harvest indigo leaves is just before the flowers open.