How to Grow and Care for Dyer’s Woad

Isatis tinctoria

Woad has been used for thousands of years to create a vibrant blue dye.

It seems almost unbelievable that such striking color could come from a plant with fairly plain green leaves, but this member of the Brassicaceae family holds a surprise.

I first learned about woad while exploring traditional fabric dyeing techniques as I had taken up a type of knitting and weaving known as nålbinding. I expected the blue pigment to come from berries or colorful petals, not the unassuming foliage of a roadside weed.

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It turns out, the same plant that ancient cultures once prized for its color is now considered invasive in some regions. But if you’re looking for a plant with a long history, useful leaves, and a tidy habit in the garden, woad fits the bill.

Woad grows one to three feet tall with a basal rosette of bluish green, hairy leaves and a single upright flower stalk that holds clusters of tiny yellow blossoms.

Whether you’re cultivating woad for dye, as a medicinal, or as a pollinator-friendly addition to a wildflower, herb, or rock garden, here’s what we’ll cover to help you grow it:

Woad has played an important role in human agriculture for centuries.

As a natural source of blue pigment, it was the go-to dye for textiles long before indigo (Indigofera tinctoria) was widely cultivated or synthetic dyes were invented.

Indigenous to the Caucasus region of central Asia, eastern Siberia, and western Asia, woad has naturalized in south-eastern and central Europe and western North America.

It thrives in regions with an average of 16 inches of rain per year, temperatures above 9°F, and elevations ranging from sea level to over 8,000 feet in the equivalent of USDA Hardiness Zones 4 to 8.

In areas with richer, wetter soil, the plants can still be cultivated but they don’t tend to spread as aggressively.

Ancient Egyptians used woad to dye cloth, and Vikings valued it too. Long before medieval times, it was a significant crop in Europe. Cities like Toulouse, France, and Lincolnshire, England, prospered thanks to their roles in the woad trade.

European settlers brought it to North America in the 1600s, including on the Mayflower. From there, it spread west, often as a stowaway in hay. Today, it grows wild across much of the US, with the exception of the midwest and the south.

Modern fiber artists who favor natural dyes still use woad.

I once spent weeks pulling what I thought was an annoying weed from my property, only to discover I’d been tossing out a valuable dye plant. A friend, who buys woad to dye yarn, was horrified.

Modern researchers are examining its anti-inflammatory properties and potential cancer-fighting compounds like glucobrassicin. It’s even enjoying a resurgence in the UK as a natural ink source.

Also known as asp-of-Jerusalem, dyer’s plant, pastel, glastum, or dyer’s weed, I. tinctoria can be grown as an annual, biennial, or short-lived perennial.

When the plant isn’t in bloom, it’s easy to identify by the white vein running down the middle of its lanceolate leaves. After flowering, the dark seed pods can give the plants a nearly black appearance, especially when they grow in large clusters.

Dyer’s woad looks like and is closely related to chinese woad (I. indigotica). This species can technically make dye, but it has never been widely used for this purpose. It’s popular as a medicinal herb.

How to Grow

Woad is an undemanding plant that does best in xeric or mesic sites, which means it needs little water, lots of sun, and really good drainage.

Light

Woad needs full sun to grow and flower at its best. While a touch of afternoon shade in hotter zones won’t hurt, anything less than six hours of direct sun will lead to weak growth and few flowers.

Shade tends to be its downfall, and it simply won’t thrive in darker corners of the garden.

Soil

This plant prefers dry, somewhat sandy soil. I always found it in Utah growing alongside species like sagebrush (Salvia leucantha) and coyote brush (Baccharis pilularis), which are known for surviving in nutrient-poor, arid ground.

It’ll tolerate richer soils, but only if the soil is well-draining. Avoid planting in heavy clay or compacted loam.

Water

Woad is drought tolerant once established and prefers to dry out between waterings.

Overwatering can easily lead to rot. Water sparingly and only when the soil is dry a few inches down.

Fertilizing

The plants have a low nitrogen requirement and happily grow in depleted soils. But if you’re cultivating it for dye production, feeding in the spring can boost foliage growth.

Use a nitrogen-rich amendment such as blood or feather meal, which encourages leafy growth.

You can also apply a layer of well-rotted compost as mulch, but keep it light to avoid enriching the soil too much.

Down to Earth Feather Meal

My go-to is Feather Meal, and you can find it in four-pound packages from Down to Earth at Arbico Organics.

Side dress the plants just as the leaves begin to emerge in early spring. Feather meal is slow-releasing, so it will continue to feed the plant throughout the spring and summer.

Where to Buy

Woad isn’t common and you probably won’t even find it in specialty nurseries.

You’re probably going to have to go looking online. Stores that specialize in dye plants or medicinal herbs will often carry the seeds.

Maintenance

These plants are typically monocarpic, which means they die after flowering.

When a plant finishes blooming, go ahead and remove the dead material to keep pests and fungi from taking up residence in the decaying foliage.

The crown and roots can sometimes survive into the following year. But unless the plant experiences at least a month of temperatures below 39°F, it won’t rebloom.

If you want to prevent it from spreading, cut off the flower heads before they set seed. Woad reproduces only by seed, so if you stop the seeds from forming, you stop the spread.

The good news is that if some root is left behind, the plant won’t regenerate from a buried, broken piece like dandelions or chicory can.

If your goal is to make dye, harvest the leaves in the summer of its first season. This is when the plant has the most indigo concentration in the foliage.

Propagation

Woad spreads by seed, not by roots or stems. While you won’t find seedlings for sale, seeds are easy to source – or you can collect them yourself.

The flowers are tiny, appearing in large clusters on multistemmed branches in April, May, or June depending on the location.

After the flowers fade, they form winged fruits that may be green to purple or nearly black. They will fall from the plant and germinate right away or may overwinter and emerge in the spring.

To harvest, take one of the long seed stalks and rub it between your palms. The fruits will release into your hand and you can blow away the chaff.

Poke the fruit with your fingernail or a knife then peel away the flesh to release the seed inside.

Rinse to remove the flesh then let the seeds dry on a paper towel. After drying, you can store the seeds in a jar or envelope until you’re ready to sow.

Always remove seeds from the fruit before planting – germination is significantly slower when they’re left inside.

Sow seeds in fall or a few weeks before the last frost in spring. No stratification is needed, but soaking the seeds for up to eight hours can help soften the shell.

Fall sowing often produces larger plants, while spring sowing tends to yield better germination.

Pests and Disease

Dyer’s woad is generally unbothered by most herbivores.

Deer, rabbits, and livestock avoid it, though goats or sheep might nibble on young spring growth if they are really hungry. Birds may eat the seeds, but that’s not necessarily a bad thing.

You might occasionally see aphids and without a doubt slugs and snails, but that’s about it when it comes to pests.

Cabbage whites will feed on the plants, but they much prefer other brassicas.

Rust (Puccinia thlaspeos) is extremely common on wild plants in the western US. It’s so effective at weakening plants that it’s used as a biocontrol in areas where woad is invasive.

Symptoms include rust-colored spots on the undersides of the leaves and white powdery fungus on the tops, as well as curled foliage and overall stunted growth.

To manage rust, spray with a copper or sulfur-based fungicide every two weeks until symptoms resolve.

Bonide Liquid Copper Fungicide

I prefer to use a ready-made liquid copper fungicide to control rust in my garden.

Arbico Organics carries Bonide’s Liquid Copper Fungicide, which always works well for me, in a variety of sizes.

Clubroot, caused by Plasmodiophora brassicae, is another disease to watch for. This pathogen causes swollen, club-like roots and is hard to detect early.

Aboveground, affected plants wilt and yellow, resembling drought stress. Unfortunately, adding water won’t help.

You’ve Got the (Woad) Blues

Depending on your garden conditions, you might spend more time trying to stop this plant from spreading than encouraging it to grow!

So what’s your story? What interests you about woad? Are you planning to dye some wool for knitting or spinning? Or just adding some pretty wildflowers to your garden? Share the details with us in the comments section below.

And for more information about growing medicinal plants in your garden, check out these guides next:

• How to Plant and Grow Feverfew: A Medicinal and Visual Delight
• How to Plant and Grow Arnica
• How to Grow and Use Motherwort