How To Wash Fresh Frozen Cannabis for Bubble Hash Guide


Todde Philips

🇺🇸 Retired veteran, father, rock-climbing expert & rosin connoisseur.

Fresh frozen cannabis refers to cannabis flowers and trim leaves that are frozen immediately after harvest. Extractors use fresh frozen cannabis as starting material in the production of bubble hash. This process is called Ice Water Extraction, which involves mixing cannabis together with ice water using either a hand paddle or a washing machine. This mixing together of ice water and cannabis causes cannabis trichomes to fall away from the material and float freely in an ice water and cannabis slurry. 

Trichomes are the tiny resin glands on cannabis flowers and trim leaves that contain high concentrations of therapeutic compounds like cannabinoids, terpenes, and flavonoids. Trichomes are the components of bubble hash, and the highest quality bubble hash includes almost exclusively trichomes with very little plant material. 

After trichomes have been knocked free from the plant material, extractors filter the trichomes out of the ice water and cannabis mixture using a series of mesh sieves, known as bubble wash bags

For a full guide to Ice Water Extraction, check out our article How To Wash Bubble Hash.

Dried cannabis flowers and/or trim leaves can also be used as starting material for Ice Water Extraction. Cannabis doesn’t have to be fresh frozen in order to make bubble hash. 

What Are The Benefits To Using Fresh Frozen Material?

The fresh frozen preparation of cannabis helps to preserve the qualities of plant while it was alive, most importantly the terpene content. Fresh frozen material is the closest thing to the living plant. Freezing (especially subzero temperatures) helps to minimize terpenes degradation and slow down the natural process of oxidation that occurs after harvest. 


Oxidation creates a darker color in trichomes. Bubble hash and rosin made with fresh frozen cannabis is normally a lot lighter in color than those extracts made with dried and cured cannabis material, as a result of only minimal oxidation on the fresh frozen. 

Terpenes not only impact the flavor and taste of cannabis, but they interact with cannabinoids and impact the overall experience of the smoke. Extractors will go to great lengths to preserve terpene content in cannabis. 

The fresh frozen preparation for cannabis also prevents mold growth, and allows extractors to keep product safely at hand and ready for production at a moments notice. 

How Is Washing Bubble Hash with Fresh Frozen Cannabis Different?

The overall process of Ice Water Extraction is the same, regardless of whether you’re using dried and cured or fresh frozen cannabis material. However, one of the trickiest elements of the process is in the preparation of the fresh frozen immediately after harvest. Preparing fresh frozen material isn’t as easy as putting fresh flowers into ziplock bags and throwing them into your freezer at home. 

To prepare fresh frozen cannabis in the most ideal way, extractors need an industrial freezer capable of reaching sub zero temperatures, a vacuum sealer machine, and plastic bags. Right after harvest the flowers are removed from the main branches and the buds are broken down into medium-sized chunks. Cannabis is placed inside the plastic bags and vacuum sealed. Then it goes into the freezer where it remains until extraction. 

It’s best not to compress the flowers too tightly with the vacuum effect, as this can damage trichomes. 

Fresh frozen cannabis should remain in the freezer for at least 24 hours prior to ice water extraction. As far as a shelf life, fresh frozen cannabis can remain in this condition for several months and maintain it’s freshness. 

Learn more about how to prepare fresh frozen in our article How To Prepare Fresh Frozen Cannabis.

How To Prepare Fresh Frozen Cannabis 

Determining your crop’s ideal ripeness is the first step to prepare the best fresh frozen cannabis material. We wrote an article to help you harvest at just the right time. Check out How To Harvest Cannabis for Peak Trichome Ripeness. 

Once harvest day finally arrives, follow this basic process: 

1. Remove fan leaves with your trimming scissors while the plants are still in their pots. Discard these leaves. Material that isn’t visibly covered in trichomes won’t be useful for extraction. 

2. Remove all branches containing flowers and place them into bins. Main branches should remain intact during the initial chopping phase. Metabolite loss is increased if the plant is rapidly chopped into small sections before the flowers are removed.  

3. Break down larger flowers into smaller chunks, into about the size of quarters. Use scissors to carefully remove each section of the larger flowers, at the base of those sections. Cut the stem of the section away from the main branch, don't cut through leaf or flower material. 

Important note: don't cut leaves in half, only remove leaves at their stems. Leaves that are cut in half will bleed out lots of chlorophyll during extraction. Be sure to minimize the amount of stems that are present in your material as well. For example, don't include big sections of main branches attached to the buds. Remove the buds from the stems. 

4. Once the buds are broken into medium-sized chunks, it’s time to place them into bags. Use bags that are large enough to hold anywhere from 2-4 pounds of product.   

5. Vacuum seal the plastic bags, careful not to overly compact the buds and damage trichomes. Adjust the setting on your vacuum sealing machine so that moderate suction power is used. It's best to leave enough air inside the bag to act as a pillow, cushioning the buds when the plastic bags are stacked on top of each other in the freezer. 

6. While some extractors aim for subzero temperatures in commercial freezers (-4 to -38 degrees F), this isn't necessary. Just a regular freezer or a chest freezer will do.   

7. Move the vacuum sealed material into the freezer as quickly as possible. Terpenes evaporate quickly in the open air after harvest. 

The sooner the flowers get into the freezer, the better. Flowers should be frozen within one hour of being harvested. Fresh frozen cannabis should remain in the freezer for at least 24 hours prior to ice water extraction.   Once the flowers are frozen, be sure to keep them frozen until it's time to wash. 

Washing the Material


Pre soaking is an important step for dried and cured cannabis material, and the same goes for fresh frozen. Even though the fresh frozen cannabis contains higher amounts of moisture, it still needs to be thoroughly soaked in ice water before mixing begins. 

The material should be soft and spongy before being washed. It’s best to break the buds apart to be sure the center is completely saturated before ending the pre soaking period. There shouldn’t be any dryness in the material. Pre soaking can take around 30 mins or so. 

Learn more about pre soaking in the article How To Pre Soak Fresh or Cured Material. 

After the pre soaking is complete, it's time to mix the cannabis, water, and ice together using either a hand-mixing paddle or a washing machine

Following the mixing process, drain the water through your series of bubble wash bags. Be sure to thoroughly rinse the hash that collects on your keeper bags before collecting. 

So how much bubble hash yield can you expect with fresh frozen material? Anything in the 3-8% range is a good yield. The rule of thumb for calculating wet (fresh frozen) weight to dry (air cured) weight is 5:1. So if you get 4% wet, that’s equivalent to 20% dry.

One of the most important steps in the hash making process is drying the fresh ice water hash. The hash will be completely saturated with water after you collect it from the bubble wash bags. If the hash isn't dried with proper techniques, it can harbor mold growth and become unusable. Moldy hash is only good for the trash. 

The key idea with drying is to break apart the hash into fine granules so that it can air dry efficiently. The techniques for air dry are straightforward and can involve either a microplane or sieve in order to break down the hash into small pieces for drying. 

If you have access to a freeze dryer, this is the best option for drying hash and allows you to avoid breaking down the hash into tiny pieces for drying. 

The process and methods for drying are the same for bubble hash made with either fresh frozen or dried cannabis material. 


The best hash is arguably made from fresh frozen cannabis material. The excellent terpene preservation and lack of oxidation with the fresh frozen preparation is evident in the final product. Although making the best fresh frozen hash requires additional equipment, including a freezer a vacuum sealing machine, if your budget can justify these expenses, then the benefits will pay dividends in your solventless operation. 

The process of ice water extraction for making bubble hash is the same for fresh frozen and dried cannabis starting material. The difference is just in how that starting material is prepared prior to the extraction taking place.

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What is fresh frozen cannabis?
Fresh frozen cannabis refers to cannabis flowers and trim leaves that are frozen to subzero temperatures immediately after harvest.

How do you prepare fresh frozen cannabis for ice water extraction?
Right after harvest the flowers are removed from the main branches and the buds are broken down into medium-sized chunks. Cannabis is placed inside the plastic bags and vacuum sealed. Then it goes into the freezer where it remains at subzero temperatures until extraction. 

What are the benefits of using fresh frozen cannabis?
Benefits include terpene preservation, reduced oxidation, prevents mold growth on the starting material, and extends the shelf life of the cannabis prior to extraction. 

Can you use dried cannabis as starting material for ice water extraction?
Yes. Although most extractors probably will prefer fresh frozen, you can also use dried and cured cannabis for ice water extraction. 

Is fresh frozen better than dried cannabis for making bubble hash?
It does have clear advantages, but dried cannabis material is also capable of producing premium bubble hash. Fresh frozen is not universally better, it depends on preference and what qualities you're trying to optimize in your hash production. 


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