How to Re-Hydrate Dry Cannabis Flower For Rosin Pressing

Viviane Schute       

Cannabis enthusiast and student of the art of solventless extraction

Effectively extracting quality rosin from cannabis flowers isn’t possible without the correct moisture content and humidity levels. Flowers grown in an ideal environment from good genetics can’t fully transform into exceptional rosin if they’re too dry during extraction. 

Excessive dryness in cannabis flowers causes decreased rosin yields, as bone-dry bud reabsorbs much of the rosin as it flows through the rosin bag. This reabsorption rate is significantly lower in flowers that contain the right amount of moisture, giving every extractor good reason to maintain correct moisture in their starting material.  

What is the ideal moisture for cannabis flowers and pressing rosin? 

Anywhere between 55-65% relative humidity (RH) and you’re in the sweet spot. To measure the moisture content and humidity of your cannabis flowers, purchase mini digital hygrometers that are small enough to fit inside your glass jars. Place a hygrometer inside each of the sealed jars with the cannabis flowers for a quick and accurate way to monitor the moisture of your cannabis. 

How to tell if cannabis is too dry?

Cannabis that’s well below the ideal humidity for pressing rosin will feel very brittle and crunchy to the touch. If you roll the flowers between your fingers with any amount of pressure, it breaks down into a dust or powder. Any sugar leaves on the flowers will be super crisp and breakable. If you smoke an overly dried flower, it will taste harsh and can leave some irritation on the back of your throat.

How to prevent cannabis flowers from becoming overly dry?

The best approach to the issue of over dryness is prevention. While rehydrating cannabis is effective in preparing material for pressing, flower that’s rehydrated after becoming excessively dry doesn’t fully recover to the same level of vitality and freshness it had previously. 


Cannabis that’s dried too quickly immediately after harvest will often be too dry for pressing rosin. In a warm and dry environment with excessive airflow, cannabis can dry out too quickly instead of evenly losing moisture content over the course of several days. 10 days is a good target for drying time after harvest. 

Another mistake is storing cannabis flowers in containers that aren’t air tight. Flowers should be sealed in order to eliminate airflow and preserve moisture content. Use glass jars with sealable lids to prevent unwanted air exchange. 

Ways to rehydrate cannabis flower

If you find yourself with a batch of quality cannabis flowers that are just too dry for pressing rosin, there are a few easy ways to salvage the material. 

Regardless of which method you choose, rehydrating should be done within a clean, air tight jar. Fill each jar about 70-80% with flowers to avoid overcrowding and store the cannabis in a cool, dark place during rehydration. 

Fruit 

Use small pieces of lime lemon, orange, or lemon peels, or experiment with a combination. You can also try small chunks of apples. Swap out the pieces of fruit daily until the desired moisture is reached. Fruit should not be left in the jars for long term storage, as mold will almost certainly grow thereby ruining your flowers. 

Note that using fruit to rehydrate dry cannabis can impart new and distinct flavors and aromas to the flowers, a disadvantage for those purists wishing to maintain the original essence of the plant. 

Humidity Control Packets

Specialty prefabricated moisture control packets like Boveda can bring your cannabis to a specific humidity. Their 62% RH packets are especially popular and utilize technology that creates a 2-way humidity control, meaning you’ll achieve the target RH with accuracy. However a word of caution: long term storage with Boveda packs can potentially reduce terpene expression over time. Like any rehydration solution, use Boveda sparingly and as-needed. 

Fresh Cannabis Leaves

If you have a homegrow and the ladies could use some trimming, take some fresh leaves and place them in jars with the cannabis flowers. 


Paper Towel Method

This is a great way to rehydrate cannabis that’s too dry with very minimal impact to the flower itself. There are a couple variations, the most basic of which involves creating little balls with pieces of paper towel and soaking them in clean water. Place these damp (not soaking wet) pieces of paper towel at the very bottom of the jar and change them out daily or as needed. 

An even better way to use the paper towel method is to fold a sheet of paper towel in half, then half again, to create a long, multilayered strip of paper towel. Soak one half of the strip with clean water and place that half inside of the glass jar containing flowers. Leave the dry half of the strip on the outside of the jar, and seal the lid. For added humidity control, you can place lettuce or pieces of bread on the inside of the jar to accompany the paper towel method, although it’s not needed. 

The paper towel method is our preferred method of rehydration when some extra moisture content is needed to bring super dry flowers into the right condition for pressing. 


With all three of these approaches, be sure to keep an eye on the RH and avoid overdoing it. Too much dampness in the jars can lead to mold growth or at the very least flowers that impart excess moisture into the rosin during extraction. 

Conclusion

The best cure is prevention, but there will be times when rehydration is in order. Remember to purchase a reliable digital hygrometer to make sure you’re achieving the ideal moisture range for pressing rosin. Add only the minimum amount of moisture needed to land in that prime range of 55-65%. 

Quality cannabis flowers that are too dry to press rosin are definitely worth saving, so make sure you use one of the simple methods above to rejuvenate your dry buds and see great quality and yields at the press.  

Peaceful Pressing!

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