Washing Buds & Water Curing: Clean Harvest or Terpenes Down the Drain?

You look forward to the harvest, the smell of the flowers, and the strain you selected. Then someone suggests washing the freshly harvested buds first.

For a dusty outdoor harvest, that sounds quite reasonable. With clean flowers, however, you may wonder what the additional effort is supposed to achieve. After all, after a grow, you want to preserve as much as possible of what the plant developed.

That brings us right into the discussion about Bud Washing. And to a question that is dismissed too quickly in the process: What happens to the aroma?

If the wash water subsequently smells of cannabis, we should talk about it. The same applies to the potential benefit for dust and the additional moisture. Water Curing is part of the discussion as well. However, it involves considerably more than a quick cleaning.

Bud Washing and Water Curing are significantly different

With Bud Washing, harvested flowers are briefly cleaned in water. The idea is to remove adhering dust and other superficial contaminants. Drying and further processing follow afterward. Depending on the method, only water is used or additives are included. With Water Curing, by contrast, the flowers remain in water for a longer period. The aim is for water-soluble components to leave the plant material. The flowers are then dried as well. The method is primarily promoted as providing a milder taste and a faster alternative to conventional Curing. 

This makes a major difference when assessing the two methods. Brief surface cleaning and prolonged soaking are not equivalent interventions. Anyone who has had good experiences with Bud Washing cannot automatically draw conclusions about Water Curing. Conversely, aroma loss during Water Curing does not indicate how strongly a short wash will affect the flowers.

Why does the wash water smell of terpenes?

This is precisely where the promise of loss-free washing becomes questionable.

In its own Bud Washing guide, Royal Queen Seeds writes that careful washing does not affect flavor or effects. The reasoning is that cannabinoids repel water and the terpenes are protected in the resin. 

That is too broad for our liking.

If collected wash water smells like the flower, this suggests that odor-active components from the flower have entered the water. This observation should not be dismissed by referring to water-repellent resin.

Aromatic compounds also do not all behave the same way. Linalool and Geraniol, for example, can dissolve in water to a limited extent. This has also been measured experimentally. While this does not reveal how much of either compound leaves a flower during washing, it does show why the explanation that “terpenes are always completely preserved” is insufficient. 

There is another aspect to smell: What we perceive as the typical cannabis aroma consists of more than just terpenes. Other aromatic compounds contribute as well. Some of them smell intensely even in very small quantities. Strong-smelling wash water therefore does not necessarily mean that a large proportion of the overall aroma has been lost. 

This leads us to a fairly simple conclusion: Aroma loss is possible. Its extent cannot be determined from the smell of the water.

For the common washing methods, we found no reliable comparative measurements that would allow us to state a general percentage. We would therefore neither promise complete preservation nor claim that washing ruins the flavor of every flower.

However, anyone who places particular value on intense terpenes and a strain’s original character should factor this potential loss into the decision. It is just as much part of the trade-off as the dirt you want to remove.

And what about THC and the trichomes?

Water solubility is only one part of the issue. Resin can also be lost without dissolving.

Trichome heads can be damaged or detached through handling of the flowers. This is not limited to the discussion about washing. Post-harvest processing studies, for example, show differences between hand-trimmed and machine-trimmed flowers. However, they do not indicate how much is lost with a specific Bud Washing method. 

For the question of THC, this means that “it barely dissolves in water” is no guarantee that nothing will be lost during the overall treatment. If a resin-containing gland head becomes detached, the water solubility of its contents is irrelevant.

Even so, it would be excessive to immediately infer a major loss of potency from this potential loss. Suitable comparative data are lacking here as well.

In any case, we would not judge quality solely by THC. A flower can still produce strong effects and nevertheless have lost quality for someone who selected it for its aroma.

Bud Washing can offer a reasonable benefit when there is dust

An outdoor plant is not exposed to the same conditions everywhere. A sheltered patio is different from a location with frequent dust deposits. That is why neither “outdoor plants must always be washed” nor a blanket “washing does nothing” convinces us.

Saharan dust is a good example. Such dust events do not affect only regions directly adjacent to the desert. Dust is transported across the Mediterranean region and regularly reaches other parts of Europe as well. Copernicus documents corresponding events as far as Western and Central Europe. 

If there is actually a visible layer of dust on the plants, it is understandable to want to remove it before further processing. For loosely adhering particles, a cleaning effect from water is plausible. Washing is also used with other plant products to reduce surface contamination. However, this does not mean that everything can be removed completely. 

We found no direct comparative data for cannabis flowers after a Saharan dust event. We therefore cannot promise a specific cleaning result.

Nevertheless, this is a different starting point from flowers without any recognizable contamination. With a clearly dusty harvest, a potential loss of aroma is at least balanced by a specific cleaning purpose. With already clean flowers, you would first need to explain what additional benefit the washing is supposed to provide.

For us, the actual contamination is a better decision criterion than whether a plant was grown indoors or outdoors.

The additional moisture is part of the decision

After washing, the water has to leave the flowers again. This sounds obvious, but it is one of the decisive points.

Moisture allows microorganisms already present to multiply under suitable conditions. Studies on cannabis show that drying influences the subsequent yeast and mold burden. This is not proof that Bud Washing inevitably causes mold. It does show, however, why washing should not be assessed separately from the drying that follows.

The wash water itself is another factor. It can absorb contaminants, but it can also distribute them between different plant parts. This issue is known from the processing of fruit and vegetables. Particularly with shared or reused water, the contamination level in the water can build up.

The concern is therefore not that every contact with water is automatically problematic. The point is that cleaning creates an additional step in which something can also go wrong.

Anyone who already has difficulty with drying should not ignore this when making the decision. Washing does not solve problems with persistently moist flowers. And a flower that is clean on the outside can still spoil later.

Mold cannot be reliably washed away

With mold, we would not try to make the harvest suitable for consumption after all by washing it.

An infected flower is different from a flower with dust on its surface. Royal Queen Seeds also explicitly distinguishes existing fungal infections from the potential benefits of Bud Washing. 

There are also possible fungal metabolites. Some molds can produce mycotoxins. Many of these substances are relatively stable. Therefore, just because a visible coating has disappeared does not mean that potential contamination has disappeared as well. This also applies when a washing additive is used. For a specific treatment, it would first have to be shown that it reliably eliminates the relevant contamination. We could not find such a procedure among the usual household methods.

As frustrating as infected buds are after a long grow: Washing is not a reliable rescue method for moldy flowers.

With pesticides, reassurance would be just as premature

Plant protection products and other residues also cannot be treated as one uniform group. Which substances are present and where they are located makes a difference.

With food, washing can reduce residues. Nevertheless, residues may still be present after cleaning. The National Pesticide Information Center also points this out. A general assurance such as “pesticide-free after washing” cannot be derived from this. 

This applies even more to cannabis: Without knowing what a plant was treated with, the success of washing cannot be reasonably assessed.

We would therefore not present Bud Washing as subsequent protection against unknown sprays. The method can provide surface cleaning. However, it does not replace knowing what type of contamination is present in the first place.

Water Curing changes more than just the surface

With Water Curing, the entire question shifts. The aim is not merely to remove adhering particles. Prolonged contact with water is intended to draw components out of the flower.

Supporters describe the result as milder and less intense in aroma. Royal Queen Seeds also explicitly mentions losses in smell and flavor with Water Curing. What Bud Washing is intended to preserve as much as possible is presented here partly as an accepted disadvantage or even an advantage. 

For someone who deliberately wants a less intense aroma, this may sound interesting. Anyone growing a strain for its aroma and flavor is likely to assess it differently.

For us, Water Curing would therefore not be the first choice when preserving the original aroma is the priority. Less smell may be desirable. But it is not a general improvement in flower quality.

Furthermore, the process cannot be reduced to the appealing idea that only unwanted substances are extracted. The fact that a component is water-soluble says nothing about whether you would want to retain it in the finished flower. This also applies to aromatic compounds such as Linalool. 

Does this wash out the chlorophyll?

This explanation frequently appears in connection with Water Curing. In this simplified form, it is not correct.

Natural chlorophyll is fat-soluble and does not simply dissolve in water. Green water can still occur, for example due to fine plant particles. The discoloration alone therefore does not show how much chlorophyll has actually been removed from the flower. 

This does not mean that prolonged contact with water leaves the flower unchanged. It only means that “the water draws out the chlorophyll” is not a sufficient explanation for all the changes.

For the assessment, it is more important how the finished flower smells, tastes, and feels. The color of the water alone says little about this.

Is the result really milder and healthier?

A less harsh result may feel more pleasant subjectively. No one should be denied that experience. However, it does not automatically follow that fewer harmful substances are absorbed.

Even cannabis smoke perceived as milder contains irritating and harmful substances. We found no robust direct comparative data demonstrating a health benefit from Water Curing. We would therefore stick to the description that can actually be assessed: Someone perceives the result as milder. The broader claim that it is therefore safer requires separate evidence.

And why is it supposed to be stronger afterward?

Here, effects and active-compound content per gram are easily confused.

If a treatment removed other components while the quantity of active compounds remained completely intact, the active-compound content per gram could increase. However, there would not be more active compounds overall. There would simply be less remaining mass.

Whether a specific water treatment actually works this way would have to be measured. In any case, this does not support a blanket promise that Water Curing makes the harvest more potent.

How we assess Bud Washing and Water Curing

We would not reject Bud Washing outright. With clearly adhering dust, there is a reasonable basis for considering cleaning. However, a potential cleaning effect is different from a guaranteed improvement in overall flower quality. 

With clean flowers, we would take a more cautious approach. If there is no specific problem, we see no compelling reason to treat the harvest additionally simply out of habit. Especially when aroma is the priority.

We would assess Water Curing differently again. It is a deliberate alteration of the plant material and is associated even by its proponents with less smell and flavor. As a method for producing flowers that are as unaltered and aromatic as possible, it would therefore not be our first choice. Royal Queen Seeds

What we feel is missing from the discussion above all is an honest approach to the potential losses. We do not need to claim that every wash ruins the terpenes. But we should not promise that everything is guaranteed to remain intact either.

Our starting point would therefore always be: What do you want to remove from the flowers, and what potential disadvantage are you willing to accept in return?

With a dusty harvest, the answer may be different than with clean buds. With mold or unknown residues, however, washing is not sufficient protection. And anyone interested in Water Curing because of a milder taste should know that less aroma is not an unexpected side effect, but part of the trade-off.