Bleached: The Cost of Altered Floral Materials

If you follow the flower world and are tied into the commercial flower markets, you’ve likely also been flooded with advertisements for bleached, dyed, and painted plant materials in the last few weeks leading up to the holidays.

The “big” flower industry seems to be meeting the every want and desire of anyone who ever dreamt that a fern could be white, or blue, or sparkly. There is a constant streaming supply of altered plant and flower materials coming through the flower markets these days, and many folks are taking note. Some argue that there is a creative use or a “right time and place” to build with these materials.

I’m intrigued by the eclectic, the unusual, the surprising. I love using materials in different ways. There’s so much innovation in any kind of design work. But, I think these products cross a line. I know they do.

This week, I spent some time trying to learn more about the bleaching of flowers. (You can learn about the dying and painting of flowers in Amy Stewart’s New York Times Best Selling expose: Flower Confidential: The Good, the Bad, and the Beautiful.) Hold on tight- that book is an incredible inside look into the love and dedication that fuels “big” flower growing, but also the darker (much darker) reality of the true costs of the big commercial flower industry to our environment and health.

Anyhow- The thing that put me over the edge in terms of digging into the matter were advertisements for bleached Italian ruscus. Ruscus is a hardy greenery on tall stems. It is a little shiny and waxy, and it holds up well without water. It is great for event work, even in very hot weather. And- if you’re able to re-collect it, you can use it again for another event. It also seems to be available pretty much year round. These properties have made it a favorite of florists.


What concerned me (and continues to concern me) is the extent that I imagined you’d have to go to remove the color from this rugged plant. I guess I imagined that it might be easy to bleach the delicate little ferns that I’ve seen offered before. I started to worry that a complex chemical cocktail might be the main ingredient in the recipe. Unfortunately, I wasn’t able to find a trove of information about plant bleaching. But I did find this— a virtual “how-to” guide published by the Government of Western Australia, called “Bleaching Plant Foliage” in December of 2016. Read on for their recommended course of treatment for the bleaching of plant materials. Take special note of the second to last chemical on this list. It is cheap. And nasty. I think you get where I’m headed. If the reading is dull—hang in there—or scan right through. I trust you get the drift. I’ll be right back with you in a moment below.

“Types of bleaching products

Hypochlorites (NaOCl, Ca(OCl)2)

Hypochlorite bleaching is usually done cold to minimise cellulose fibre damage. For the same reason, concentrations seldom exceed 4%.

Hypochlorites are available from swimming pool chemical suppliers as either solid calcium hypochlorite or liquid sodium hypochlorite (12% solution). Supermarkets sell formulations of about 5% strength.

Hypochlorites in solution are stabilized at pH 11. They can be used to bleach at this pH but will act relatively slowly (12 to 15 hours). Acid is added to reduce the pH.

Hypochlorites release acid as they decompose so the initial pH of the batch must be set high (usually around 10.0, depending on concentration) to make allowance for the fall in pH during bleaching. Alternatively, a pH buffer such as borax can be used to hold the pH steady. Bleach decomposes too rapidly for maximum efficiency if the bath pH falls below 8.5.

To prevent the alkalinity from damaging plant material, hypochlorite bleaches are usually followed by a weak acid wash.

Sodium chlorite (NaCl02)

Chlorite bleaching is normally done between the temperatures of 50 and 100°C, the optimum being 70°C.

Sodium chlorite is available either as a 40% solution or as a solid in 125kg drums. It is expensive but is the most efficient bleach for lignin without damaging fibre. Chlorite-bleached material is not usually susceptible to yellowing with age. Chlorite is stable above pH 7 and optimum release of bleaching agent occurs between pH 4.5 and 3.5, so acid must be added. Below pH 3.5 the chlorite decomposes too rapidly for efficient bleaching.

Various chemicals (hydroquinone, aldehydes) activate chlorite bleaching power. It is common to impregnate the material with bleach at pH 5 (where chlorite is stable) and then transfer to another tank containing the activator. This practice conserves bleach because only the bleach in contact with the plant material is activated to decompose.

Peroxide (H2O2, NaH2O2 )

Hydrogen peroxide is available commercially as a 50% solution. Typically, peroxide will remove about half the lignin before cellulose fibres are damaged, hence it is an ideal first bleach in a multi-step process. However, a light peroxide bleach is often used after chlorite bleaching to increase resistance to yellowing.

Peroxides are extremely sensitive to trace metal contamination, which causes rapid decomposition. Add sodium silicate (1%) to chelate any metal and to adjust the pH to the correct value. Peroxide bleaches best at pH 10.5. Above this point it becomes unstable and decomposes too rapidly, whereas a lower pH results in a slow rate of bleaching.

Hydrosulphites (NaS2O4, ZnS2O4)

Hydrosulphite is widely used for paper bleaching. It is available commercially as either sodium or zinc hydrosulphite (also sold as dithionite) and is a cheap but smelly reductive bleach. Hydrosulphite has maximum bleaching power at pH 5.5 to 6.0. It is stable in alkaline solution. Hydrosulphite can be made in situ by alkaline treatment of sulphur dioxide gas.

Borohydride (NaBH4)

Borohydrides are not presently used for commercial bleaching because of their high cost, although they may have specific applications in the future.”

Now- that was quite a exercise in decoding basic (haha, sorry for the pun) language from chemistry class. But- for me, anyways, chemistry was never simple. OK— back to the process. Now the plants are bleached. That’s it, right? They’re ready to be dried and then to head out the door to the international flower markets. WRONG. Now they may need a nice little something to prevent them from yellowing. Here’s what the article suggests:

“Control of yellowing

The extent of yellowing upon aging of bleached material depends on the thoroughness of the original bleaching regime. Generally, multi-step bleaching especially when it alternates an oxidative bleach with a reductive bleach, creates a product that yellows much less than a product from a single-stage bleaching.

A final wash in a 2% solution of barium hydroxide, calcium hydroxide, sodium bicarbonate or aluminium sulphate prevents yellowing.

Incorporation of optical brighteners (from dye manufacturers) or pigments, such as titanium dioxide or zinc oxide, 'masks' a slightly yellow product.”

OK— that must be it, right?! NOPE. Next the plants/flowers that have been bleached with any of the chlorine-related chemicals need to be, I guess you could say, made “un-smelly.” So they are treated with a diluted “solution of thiourea or sulfur dioxide (as metabisulphite or hydrosulphite).”

The author continues, “Sulphur dioxide can also conveniently be applied as a gas.”

Sidebar - what is sulfur dioxide again? Oh— OK— Wikipedia helped remind me about this one: “Sulfur dioxide in the air comes mainly from activities such as the burning of coal and oil at power plants or from copper smelting.” Eeeeeeew.


Now our plant material has been bleached, protected from yellowing, and made “unsmelly.” There is one more thing to do before it goes out the door. We need to strengthen it again. All of those treatments have (not surprisingly) weakened the natural material. So - lastly, add a humectant (water-attractant) back to the plant with calcium chloride, sodium chloride, or glycerine.

But, the article warns:

“Caution: Glycerine and bleach will explode on contact.”

Yikes. This is exactly the kind of cocktail I feared might be behind those frilly white greens…

So, if you’re worried about explosions the article advises that, “Starch or water-soluble plastic adhesives, such as polyvinyl alcohol, may also be suitable.”

Yes- “water-soluble plastic.” What kind of affect does that have on the environment? Hmmmm.

Now, let’s think about the costs. The cost of one stem of that bleached, un-yellow, un-smelly, strengthened ruscus. After all those steps. One bunch is $23 (Mayesh Wholesale price quote on December 5, 2018). One bunch is “mostly 10 stems per bunch” - so therefore a stem is about $2.30. Consider that this cost includes growing the plant, harvesting the plant, storing the plant, shipping the plant from the grower to the “bleacher,” all the chemicals that will be used, the humans that have to interact with the chemicals, the expense of maintaining (or not) a healthy workspace, the disposal (scary thought) of the chemicals, and the packaging and shipping of that stem so that it can get to the marketplace. I’m sure I’m missing a few steps here. Some people might say, “what a value!” I’d argue that we are paying little for quite extensive damage to ourselves and the planet.

I don’t have access to the aisles of the world’s big flower markets. I see only what is available to me readily through wholesale distributors who would have me order in all my goods. But what I see is troubling. Take a look now through the lens of one of my favorite designers, Lewis Miller of Lewis Miller Design, NYC. These are images from his Instagram account. I love the caption, “A literal #wtf - the flower market has become an invasion of ugliness.” And Emily Thompson ads: “And dead dried things! Poisoned bleached and spray painted”.

It all makes me ask why and who? Why - are these products wanted? Who - finds themselves above Mother Nature? Her grand plan of colors is the florist’s paint box. It seems almost like copyright infringement- the re-coloring of her logos, the twisted manipulation of her brands. I’m sure you could apply that thinking to a great many things we do in this world.

I think the beauty of floristry is in the artist’s ability to see Mother Nature’s colors and bring them together in ways that serve the flowers - that make them more beautiful because of their company or the attention brought to the special, imperfect curve of a stem. Those ways that call out the subtle inconsistencies in one bloom’s mauve tones and move the color through the rest of the arrangement’s flowers are artful. If you can make a “loving family’ of varied un-messed-around-with flowers - that’s what I want to see.

Please, flower industry, put down your spray paint, glitter, and hydrosulphites.

Have a comment or idea to share? Please chime in through the comments section below. I’d love to hear from you.