white ash weed

White or Gray: Does Ash Color Determine Quality Cannabis?

Wednesday January 2, 2019

S herlock Holmes is said to have penned Upon the Distinction Between the Ashes of the Various Tobaccos as a guide to understanding cigar ash. Now, over a century later, armchair sleuths claim to have their own ways of reading cannabis ash. All across the Internet, cannabis boards rage with fierce debate and almost no scientific input over one of the most inane topics in cannabis: what does ash color mean for bud quality?

The Cannabis Ash Debate

The argument goes that properly flushed and/or cured (more on this in a moment) cannabis will burn to white, or near-white ash when combusted, and darker, blacker ash is an indication of inferior product. Most everyone agrees that cannabis should not pop or crackle when burned. There is some degree of disagreement over what constitutes “white” ash and just how deep into the spectrum of gray is still acceptable.

And just what inferiority does ash color betray? Supposedly, darker ash means that chemicals used in the growing process are still present in the plant, which are ideally harmful to humans when smoked and inhaled. To help get to the bottom of the cannabis ash argument, let’s take a closer look into some key elements surrounding the subject.

Is Flushing a Fraudulent Factor?

The majority of proponents of the cannabis ash idea feel that white ash is indicative of cannabis that has been properly “flushed.” For those unfamiliar, flushing is the practice of feeding the cannabis plant only water in the last seven to fourteen days of growing in order to “flush out” any residual chemicals or nutrients used to bolster the growing process – synthetic salt-based fertilizers in particular. Flushing is such a common practice that the majority of growers consider it a standard step in the cultivation process, never to be skipped. Renowned grower Jorge Cervantes even penned an article on the importance of flushing. The majority of growers we spoke to agree, flush has a very noticeable effect.

However, the very practice of flushing is a topic of fierce debate. A few growers feel it is an unnecessary – and even potentially harmful – step to the finished product. They claim that the logic behind flushing is flawed, and that the science behind it makes little sense. In an op-ed published in Cannabis Business Times, licensed agriculturalist and cannabis entrepreneur Katie Badertscher explained the inconsistency to the widely-held belief: “To us, the concept that flushing somehow changes the chemistry in plant tissue that has been laid down for weeks requires a scientific explanation because that concept seems akin to claiming that the car engine is cleaner after washing the car’s hood. Nutrients are locked in the plant, and an external flush cannot undo the complex biology that locked them in.”

Many growers say their bud burns to white ash regardless of flush, and that any properly grown cannabis will do the same.

So, if ash isn’t a good indicator of flush, is it an indicator of anything else? Some proponents of the “ash test” claim that what it’s really showing is the quality of the cure.

Correlation between Cannabis Curing and Ash Color

Curing is a process of preserving food against degradation and bacteria for later consumption. For cannabis, a cure is done to seal in desirable cannabinoids and terpenes, and thought to purge excess starch and sugar. While both deal with reducing the moisture content in flower, curing is distinguished from drying, as it involves carefully controlling the release of moisture from sealed containers over an extended period.

While we were able to find lots of anecdotal references and explanations of this process, we weren’t able to come across any hard scientific clarifications that back up the validity of the “ash test.” Curing undoubtedly results in a smoother, more flavorful smoke, but similar to flushing, understanding exactly why remains a mystery. The Cannabis Business Times covered similar Badertscher frustrations at understanding the underlying processes of cannabis curing, and offers some questioning to the commonly held beliefs here.

The best understanding we could muster is that similar to fruit on a plant, harvested buds do not begin to immediately decompose, but continue to undergo metabolic changes for a period. By controlling the amount of moisture in the buds during this crucial period, growers are able to coax those metabolic processes into reducing undesirable elements out of the plant to increase smoothness. Moisture content is at the heart of the matter, which also unquestionably affects a bud’s smoke quality.

Where Does the Ash Myth Come From?

For how persistent the white ash test is in the cannabis world, its origins appear to have come from connoisseurs of a completely different crop. The insistence that white ash equates to higher quality product comes from cigar aficionados. The Cigar Association of America even notes the fact on their website.

The story goes that when the US ceased trade with Cuba, imitation Cuban cigars flooded the market, and could be distinguished by their darker ash color. Tobacco grown in authentic Cuban soil was higher in minerals and nutrients, cigar historians argue, resulting in lighter ash. In modern cannabis grow markets, where nutrient content can be carefully monitored, and a variety of methods are used, ash color is unlikely to definitely differentiate or distinguish the quality of the source.

Trust Your Omens

Regardless of the exact processes that the ash test is meant to illuminate, one thing about the result is certain: if bud harshly fails the ash test, it’s usually a sign of something you don’t want to smoke.

Bud that crackles when ignited, or burns to black and/or sticky ash tends to be harsher, and unpleasant to smoke. It is likely a sign of something undesirable on the flower.

It is unlikely that well-grown and prepared cannabis would do much other than burn to gray or white ash. Conversely, you probably don’t need to be a snob about having ash as white as driven snow. So long as the smoke is smooth and flavorful, it’s probably good bud.

Ash color itself requires further scientific inquiry to support the notion that it is a good determinate of quality, but there is a bit of worthwhile information one can learn from observing what happens when flower burns.

What are your thoughts on the “ash test?” Do you feel that white ash is an indication of quality cannabis? Share your input in the comments below!

Matt Mongelia holds an MFA in writing from The School of the Art Institute of Chicago. He has worked in the cannabis industry in various roles for 4 years, from dispensaries, production and retail to events, content and marketing. He is a writer for the comic Dark Beach, and has previously covered music and cultural content for SOL REPUBLIC.

The ash test" has been a determining factor for quality cannabis for quite some time

Ash: The Not So Black and White End to Every Joint

Ah yes, a bud so pure it burns to reveal ghostly ash. Perhaps it is reasonable to think this must be healthier. No one wants to think of black smoke filling their lungs with carbons and tar. The belief that miner’s lung is a problem with cigarettes and not cannabis is one many can liberally share. Despite this, can the contents left-behind in the ashes truly serve as a measure of observation?

Coughing up a lung while smacking out chalkboard erasers may be a thing of the past. Think about that white plume of dust filling your lungs, though. Perhaps white is not as nice as our general assumptions.

White lies

Inorganic nutrients might comprise much of the white pigment you think is pure ash. Cigarette companies have known this, actually adding chalks to produce a nicer looking burn on their product, or even slow the burn down. Agents to control burn temperature and time are also added to many rolling papers, too. Good old slow-burning papers.

Oh, how the wholesome appearance of white seems so innocent. As white as winter’s first snow, a sprinkle of icing on a cake, or a dusting of chalk.

The wettest black

Many think black ash is a sign of residual nutrients and pesticides, in reality, it can be much more simple. Black ash can be created by lower temperature embers produced by a flower that is to damp. Wetter buds with a colder burn will leave behind ashes dense in black carbon.

So, even if the grower flushed and avoided any sprays their buds may burn as dark as night with an abysmal crust if they were not cured to perfection.

The hottest ash

On the other spectrum, the desert-dry buds found in those nearly antiquated bottles of legal weed will burn completely white. Drier buds burning at a higher temperature will vaporize organic carbon and nitrogens. This is caused by additional heat produced by a brittle material.

Hot embers created by an utter lack of moisture will remain far richer in calcium, magnesium, sodium, potassium, silicon and phosphorous.

Residual pesticides can either leave behind ash white as snow or black as night. Potassium salts, nitrates, and carbonates will actually promote combustion which helps produce whiter ashes, whereas residual sulphur or chlorides burn dark.

Flushing out… sugar?

Flushing may help biosynthesize the remaining nutrients into active ingrediants. As it turns out though, two weeks of straight water won’t completely remove the nutrients if your growing medium is soil. So if flushing does not reduce the overall mineral content, why else does it increase bud-quality?

One theory suggests flushing won’t decrease nutrient content, but instead chlorophyll, which is known to burn black and reduce quality.

Other aspects of the growing cycle can be manipulated to reduce chlorophyll as well, such as cold temperatures and darkness. A balance must be maintained, though. Precious terpenes and cannabinoids will also oxidize and decay with age and excessive processing. Unfortunately, quality will never recover once the aromatic profile is lost, but without chlorophyll, the colour of the remaining ash will still be white.

Ash simply is not a symbol of purity in a bone dry, irradiated flower; the drier the flower the whiter the ash.

Quantitative versus qualitative

Our eyes cannot analyze chemical data any better than our palettes. Many hidden toxins are allowed in the system, right under your nose. The only way to truly know what is in your smoke is through detailed lab testing. As much as ‘mandatory’ Myclobutanil tests sound ideal, there are other horrible toxins hidden in nearly everything Health Canada has approved.

Tests that scan for organo-nitrogens and phosphorous compounds are necessary to know if a bud truly burns clean. That much is currently possible, but not being done by licensed producers.

What no approved lab will do, is find out what permitted pesticides reside on your packaged flowers. Or, how much ethoxylates, propylene glycol, or vitamin E oil is left behind from a pesticide’s inert ingredients. No one knows how much (eg.) formaldehyde and hydrogen sulphide each producer’s cannabis smoke contains. That is, “how much,” not, “if.”

Lab testing is the only answer, not white or black ash. Unfortunately, Health Canada hasn’t set the right parameters to help keep us safe. Sorry for the bad news #whiteashgang

The black ash headache could be real though. We will explore what causes migraines in a following segment.


M Roggen. A Justice. White Ash Versus Black Ash. 2019. CBT.

Photo Courtesy of Cannabis Wiki

Ash – Ah yes, a bud so pure it burns to reveal ghostly ash. Perhaps it is reasonable to think this must be healthier. No one wants to think of black smoke