How to Grow Dyer's Woad (Isatis Tinctoria)

by Matt Gibson

Dyer’s woad has taken a back seat in practical usage as a dye to more modern coloring techniques, and it is seldom grown as a decorative flower. However, it was widely grown in ancient days for its deep blue dye, which was used for dying fabric and clothing, as well as decorating the bodies of Celtic warriors to make them look more fearsome during battle.

However, a patch of woad plants in a garden bed, though hard to get rid of if you change your mind, is quite a sight to see. Woad is a biennial, adorned with large clusters of vibrant yellow-gold flowers that bloom in early summer before transforming into flattened, dark, lantern-like seed heads, which are often considered to be more decorative than the flowers themselves. After the plant dies and dries up, the seed heads remain standing, and their strange silhouettes cast will looming shadows to remind you of the plants that grew wildly just months before.

The blooms adorn stalks that are branched at the top and fastened together with long, elegant, blue-green leaves. The leaves are what produced the dye that woad was cultivated for in the plant’s traditional usage. The simple process involved collecting the leaves, drying them, and infusing them with lime water to produce the deep blue dye. Woad dye was eventually replaced with indigo, and the dyer’s woad plant was all but forgotten—until now.

Dyer’s woad grows three to four feet tall and 18 inches wide within its first year. In the second year, it flowers, seeds, and then dies. Outside of its natural growing area in Europe, woad is widely considered a noxious weed, as it is always in competition with indigenous species wherever it grows. Native to southern Russia, woad now grows plentifully all over southeastern and central Europe as well as western North America.

In a garden setting, dyer’s woad is not only a showy addition to garden banks and slopes, it’s also a great plant for attracting birds and butterflies. It also needs very little maintenance or care to flourish. As long as you’re okay with keeping dyer’s woad around for the foreseeable future, there are no downsides or precautions to consider before planting.

Growing Conditions for Dyer’s Woad

Dyer’s woad is hardy in USDA zones 4-8 and heat zones 1-8. It prefers full sun (though it will do fine in partial shade) and flourishes in well-drained soil of just about any type. Chalk, clay, loamy, sandy, acid, neutral, or alkaline, the specific makeup of your ground makes no difference to woad. Though it will grow in any soil type, dyer’s woad does prefer a neutral to slightly alkaline soil type when possible.

This easy-go-lucky plant doesn’t even need fertilizer to thrive, though fertilization doesn’t hurt woad and can even spruce up its second-year blooming. Alternate the grow site every time you plant, as dyer’s woad will not grow successfully in the same spot for multiple years. For these reasons, do not plant woad in the same area where you have been growing other brassica plants.

How To Plant Dyer’s Woad

Dyer’s woad is usually grown from seed, and that is the method we suggest for cultivating them. After the final frost date, sow your woad seeds wherever you want them to grow. Remove any weeds, and rake the planting site until the soil is light and fine. While raking, add in some slow-release fertilizer if you wish.

Plant woad seeds two to four inches deep and 18 inches apart in rows spaced at one- to two-foot intervals. You can also harvest your own dyer’s woad seeds by taking them from dead woad plants, so if woad grows wild in your area, don’t spend money on seeds that you can just as easily grab for free from neighborhood plants. (However, it’s good form to ask if you want to collect seeds from another person’s garden. Do unto other gardeners as you would have them do unto you.)

Care for Dyer’s Woad

Watering regularly and removing competing weeds will work wonders for the health of your dyer’s woad plants. Prevent self-seeding by removing the flowers once they start to fade and before they develop seed pods. To do this, sterilize your pruning shears with a cloth soaked in rubbing alcohol, then prune woad stems at their base. Put the stems in the trash, and then re-sterilize the shears.

Garden Pests and Diseases of Dyer’s Woad

There are no known pest or disease issues that afflict dyer’s woad. Growing this hardy plant is practically free of risk.

Medicinal Uses for Dyer’s Woad

Aside from its use as a dyeing agent, dyer’s woad root has been used in traditional Chinese medicine for centuries. Its root (sometimes called by its scientific name, itsasis tinctoria root) can be made into a dried powder or a concentrated extract. Dyer’s woad has also been used as an herbal antibiotic, antiseptic, and antiviral treatment for fever, viruses, blood poisoning, tonsillitis, hepatitis, scarlet fever, and much more. Extended use for long periods is not recommended, as consuming woad can weaken digestion and cause severe chills.

Dyer’s Woad as a Fabric Dye

In ancient Europe, dyer’s woad became the predominant blue dye of choice, while at the same time, in Asia, indigo was the most prevalent blue dye. The exportation and spread of indigo was controlled by India, which met a united front of fierce resistance from other woad producers worldwide, who were fighting to keep their livelihood. Despite loads of legislation and one heck of a struggle, slowly but surely, indigo made its way to Europe, and woad fell by the wayside.

Indigo’s supremacy turned out to be short-lived, though, as synthetic indigotine hit the scene in the early 1800s and took over the market. However, there are still pockets of people who prefer to use traditional dyeing methods, and there are several websites dedicated to woad production for the purpose of dyeing and even tutorials on how to dye fabrics with woad on YouTube.

Harvesting Dyer’s Woad

Use sharp pruning shears to cut the newer leaves back. Old leaves are distinguished by their blue tint. Despite their blue appearance, the older leaves no longer contain the chemical that make woad leaves useful in dye. Cut the old leaves back as well, as it’s best to cut back everything to encourage new growth. Just don’t save the old leaves for dyeing purposes.

Using Dyer’s Woad to Dye Fabrics

Now that you have a fresh set of new woad leaves, you are ready to extract the dye. Cover fresh young leaves in a jar with boiling water and seal. Within minutes, you will see the water start to turn blue and bubble. Add alkali, then shake vigorously, and the liquid will turn green.

Dye the fabrics you have in mind with the green mixture, and once it is exposed to air, the color will change to blue. The final product must then be set in acid, washed, and finally rinsed. There are much more complete guides and tutorials available online, and the process can actually become quite complicated, so do a bit of research (such as watching the last video we’ve listed at the end of this article) before you try your hand.

Control Methods for Dyer’s Woad as an Invasive Weed

If you are not a fan of woad but you have it in your garden, good luck getting it out. Woad has an incredibly long taproot, which can measure anywhere from three to five feet long, making it nearly impossible to pull up completely. You can mow woad plants down for a temporary fix, but since they self-seed, your woad will probably sprout back before long.

A rust fungus is being investigated as a biological method of destruction, but it has not become available to the public as of yet. Other than chemical treatments that rely on harsh herbicides, which could damage your soil for future botanical residents, employing the talents of some goats may actually be your best bet for control. But why would you not be a fan of dyer’s woad? Just take in an eyeful of those lovely yellow flower clusters and realize that woad is more than just a forgotten weed that’s outlived its usefulness.

The best way to control woad is to not let it go wild in the first place. Remove flowering stems completely with sterilized shears then throw away the stems and flowers. Make sure to do this after the flowers have started to fade but before they develop seed pods. Throw away the stems and flowers, re-sterilize the shears, and you’re good to go.

Of course, you’ll still have the dead woad plants to deal with, and they won’t come out of the ground without a struggle. Again, goats and sheep love eating woad, so if you have a few friendly livestock on hand, they will happily help you handle the removal process.