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In the weeds

What to love (and do) about plant fibers

By Leslie Petrovski

During research trips to the foothills of the Caucasus Mountains in 2007 and 2008, archeologists discovered fragments of what appear to be the oldest textiles ever found: wild flax fibers dating back 30,000 or more years that had been twisted and dyed, most likely for cords or basket making.

That processed flax outlasted the millennia in a Georgian cave is hardly surprising if you know something about fiber. Plants are tough. Even soft-as-a-bunny’s-bum cotton is stronger than wool. And flax and hemp? Stronger still.

Plant fibers have their place in a knitter’s armamentarium. With summer approaching in the Northern Hemisphere, flora tend to be cooler to work with than fauna. They’re also absorbent, comfortable and machine washable. And you will never accidently full a cotton sweater.


Plant fibers also help to make the craft more inclusive. Whereas wool comes from sheep and mohair from goats, cotton, linen, and hemp derive from plants and offer stitchers a plant-based alternative to animal fibers, which not everyone can wear and some animal activists object to.

If you’ve yet to explore vegetarian yarns, they can be something of an acquired taste. Try not to compare them to their animal-derived counterparts, rather think of them like artichokes and Brussels sprouts: intriguing, useful, and full of possibilities.



Considered the humble T-shirt of fibers, cotton also has the chameleon-like capacity to gussy up for the catwalk. The fibers that spin up into this summer knitting favorite come from the cotton plant, a bushy, flowering member of the genus Gossypium. After blooming the plant produces pods (better known as bolls) that burst open to reveal clouds of soft seed hairs. Prior to harvest, a cotton field looks like millions of popcorn balls exploded in every direction.


Cotton Plant
Photo by D. Wayne Reeves, courtesy USDA Agricultural Research Service.

Cotton Field
Cotton fields at Auburn University. Photo by D. Wayne Reeves, courtesy USDA Agricultural Research Service.


All that white fluffy goodness serves as a delivery system for dispersing cottonseeds, it’s also the foundation for your favorite skein of cotton yarn. But in order to process  fiber into something spinnable, the seeds must be removed. “The seeds are loaded with oil,” says Stephenie Gaustad, star of the DVD Spinning Cotton (Interweave) and the author of an upcoming book, The Practical Spinner’s Guide to Spinning Cotton, Flax, and Hemp (also by Interweave). "That’s a problem because the oil causes contamination and fire problems. It also doesn’t make for very nice yarn."

Enter the cotton gin. Its invention by Eli Whitney, late in the eighteenth century made it possible to produce cotton textiles more efficiently without having to extract seeds by hand. (Different types of gins had been used for centuries previously in China and India.) Once ginned, the cotton lint is baled and shipped to spinning mills where it’s cleaned, carded and spun into yarn. Mercerized cotton is bathed in an alkali solution and tensioned, which straightens and strengthens the fibers while also increasing their shine and ability to take dye. 


cotton fibers
Cotton fibers before and after ginning. Photo courtesy USDA Agricultural Research Service.


The resulting yarns are somewhat of a wonder fiber. Cotton is soft, durable, resists pilling, and is incredibly absorbent. According to the National Cotton Council of America, cotton can absorb 27 times its weight in water, making it conducive to warm-weather wear, plus it gets even stronger when wet.

While wool feels warm, cotton has a cool hand, which lends itself to summer knitting. It also tends to be soft (lacking the tiny surface scales that can irritate wool wearers) and feels comfortable on the body like your favorite sweatshirt. Because of the absorbency, it takes dye beautifully. Another plus: you can easily machine wash and lightly fluff it in the dryer. As a knitter, you’ll find that cotton shows texture and lace well, so it’s wonderfully suited to summer tops, baby things (natural and washable!), springtime wraps, chemo caps, dishcloths and light sweaters.


Cotton bud
Boll weevil on a cotton bud. Photo by Jack Dykinga, courtesy USDA Agricultural Research Service.


Cotton has its downsides, however. Because it lacks the elasticity of wool, it can feel unyielding and stringy to knit with. It’s also heavy. For projects like shawls or sweaters where you want your fabric to hang in certain ways, cotton’s drape will serve you well. Knit a heavy garter-stitch jacket in cotton and it’s likely to drag the floor.

And socks? They’ll slide down your ankles unless your cotton is augmented with elastic, wool or acrylic. Happily, cotton plays well with other fibers. Blend it with acrylic, wool or viscose and suddenly you have a yarn that can be greater than the sum of its parts. For easier knitting, use wood or bamboo needles with sharp points.



Linen, which derives from the flax plant, is arguably the world’s oldest textile. Archaeologists have discovered spun and dyed flax fibers that are more than 34,000 years old. Flax is a bit temperamental to grow, requiring cooler temps and loamy soil, but requires few fertilizers or pesticides.


Flax in bloom
Flax in bloom. Photo courtesy of Biolin Research Incorporated, Saskatchewan,Canada.


Flax is a bast fiber, which means it comes from the stringy section underneath the skin or bark of the stem. The fibers are accessed by retting, a process which literally rots (rets) away the outer tissues and sticky pectins surrounding the bast bundles.  Once harvested, stems are either left in the fields—a process called dew retting—or submerged in ponds, streams or commercial vats, which is known as water retting.

After retting, the stalks are dried and then dressed. Dressing is a pretty word for the mechanical abuse process perpetrated on these plants prior to spinning. The stems are crushed to separate the useful fibers (a process known as scutching). This separates the shorter fibers (called tow) from the more desirable long or line fibers. The fibers are then straightened and combed through a mechanism called a hackler, which makes them soft enough for spinning.


Retting flax.  Photo courtesy of Biolin Research Incorporated in Saskatchewan,Canada.


Tougher and more absorbent than cotton, linen is also highly inflexible and wrinkles easily. On the needles it’s truculent, stiff and given to split. Ribbing? Forget about it. With linen, you’ll get no stretch. Even so it’s worth it. Linen acquires more luster and grace with each passing year. Think of your grandmother’s linen napkins, white and soft as meringue after decades of use. Knit something fabulous in it like a top for evening, lace gloves, or table linens that will last a lifetime. For edgings try stitch patterns or put in a proper hem. (Word to the wise: Do wash and dry your gauge swatch to ensure a good match.)



Emboldened by the passage of a new state law that allows industrial hemp farming—and more famously recreational marijuana use—this spring some brave Colorado farmers will plant their first crops of the industrial plant—a move that’s still illegal, according to the Feds. So for now, China is the leading producer of the fiber.

Unlike its psychoactive cousin, industrial hemp doesn’t pack a THC wallop. Though closely related to marijuana (they’re different varieties of the species Cannabis sativa), industrial hemp is cultivated for its health-promoting seeds and for its fiber and contains only a tiny fraction of the THC found in marijuana. To put it another way, you’d need to smoke a lot of hemp yarn to get high. 

There are many reasons U.S. farmers are anxious to grow industrial hemp. “It’s vegan and it’s such a rare thing for people to be allergic to,” explains Lana Hames of Lanaknits Designs, who began selling hemp yarn in the early 2000s. “It got a really bad rap, but it’s such a fabulous plant and it grows everywhere.” Hemp seeds and oil have become super trendy among health-conscious types, which has increased demand. It’s also an extremely adaptable plant. While flax needs cooler climes to thrive, hemp can be grown in many conditions. It requires less water and  land than cotton, needs few or no agrichemicals to be productive, and grows, yes, like a weed.

It also produces some of the strongest textiles on earth. Knitting with hemp is a bit like knitting with a skinny rodeo rope, but the yarn gets softer and more lustrous with repeated washings (some hemp yarns come pre-softened). Purportedly antibacterial, it can be machine washed and dried, delivers great stitch definition and comes in gorgeous colors.  Hemp makes a great summer tee, mildew-resistant dishcloths and sturdy market bags, but it can also go upmarket, showing off lace in a shawl, skirt or scarf.


hemp yarn
Hemp yarns. Photo by Leslie Petrovski.


Like linen, hemp is a bast fiber and its processed in the same labor-intensive and surprisingly low-tech way. The plants are retted, scotched and hackled using processing methods that remain largely the same as those used nearly 100 years ago. In part, this is because of cotton’s hegemony in the market. American policy has helped make cotton—an important U.S. cash crop—into one of the most popular fibers in the world. It’s been hard for hemp, with its shady reputation, and linen, notorious for wrinkling , to compete.

Comparing linen and hemp is difficult, because so much depends on the quality of the processing. Generally speaking, linen is the finer of the two fibers, while hemp is considered to be the stronger. Both are stretch resistant (and inelastic on the needles), drape well and cool to the touch. They can also be wonderfully lustrous.

Once you get the hang of knitting with a yarn with no give whatsoever, you might find you like it. Stitches tend to take on an architectural quality and hold their shape, so textures pop. These yarns can also look incredibly fresh and modern when you bump up the needle size, say using a U.S. size 6 needle (8mm)and lace-weight yarn.

When bast fibers are blended with wool, cotton, silk or synthetics, they accrue the softer characteristics of the other fibers while imparting a vegetal strength and beauty that make them worth a spin.