This excerpt, originally published in the November, 2019 issue of High Times magazine, is from the recent book, Marijuana Harvest: Maximizing Quality and Yield in Your Cannabis Garden by Ed Rosenthal and David Downs. Subscribe to High Times here.
Marijuana quality and potency changes over time. In the living plant, the precursors of THC and CBD are found in their acid forms, THCa and CBDa. These are not psychotropic. Only when they lose a portion of their molecules do they become active as THC and CBD. This occurs naturally over time and is accelerated in the presence of heat and light, especially ultraviolet light.
Once buds are dried and cured, potency is at its peak. Over time, THC gradually degrades to CBN, a far less psychotropic cannabinoid than THC. Research conducted at the University of Mississippi on low-quality cannabis stored for four years at room temperature (68-72°F, or 20-22°C) found that the percentage loss of THC was proportional to time in storage, with the greatest loss in the first year. As the THC level declines, the concentration of CBN increases.
This research is consistent with the experiences of marijuana users. Marijuana loses potency over time as the psychoactive THC converts to CBN, which induces sleep but not highness. Storing buds in the freezer or refrigerator slows deterioration. Freezing keeps buds fresh longest. However, even then THC deteriorates, at nearly 4 percent a year. In deep freeze (below 0°F), deterioration slows further. At refrigerator temperatures, THC deteriorates at the rate of a bout 5.4 percent a year. A freezer is best for long-term storage; a refrigerator is good for protecting terpenes in the short term. There are several problems with storing marijuana in a freezer, especially when super-cooled to 0°F (-18°C).
Even under higher temperatures in the freezer, glands become very brittle and are easily and inadvertently shaken off buds. For that reason, once placed in the freezer the container should be handled very gently, and when removed the buds should be given time to warm up so they become more pliable.
The moisture in the container freezes and can form ice crystals, especially during long storage. This may also occur when buds have not been dried sufficiently.
However, in several experiments, properly dried marijuana in a plastic container developed no ice crystals when placed in a freezer for several months. The trichomes remained intact. If moisture is a problem, vacuum sealing mostly eliminates it, although the process may result in crushed buds. Another solution is to remove the air with moisture-free gas such as carbon dioxide or nitrogen. These can be injected into the container as the ambient air exits through another hole. Then both holes are sealed.
When freezing marijuana in glass containers, choose shoulderless containers, as shouldered containers are more likely to develop cracks. Metal and wood containers can also be used for freezing.
One way to store frozen marijuana is in small containers. Pack just enough for a week’s use in each container. The rest of the stored material is not disturbed, so the glands are not at risk, as they can be removed from the freezer individually.
According to the University of Mississippi study, refrigerator temperatures slow deterioration to a little less than 0.5 percent a month, which isn’t noticeable when storing for just a few months. Here, too, it is best if the bulk of the stored material is disturbed infrequently.
Heat and light, especially UV light, evaporate terpenes and erode quality. Only an opaque container will completely protect the terpenes, and therefore the quality of the buds stored inside. An opaque container with a white exterior reflects heat, keeping the contents cool. Using a desiccant packet that maintains a set humidity of about 60-65 percent ensures the proper level of moisture is retained without causing mold.
Terpene molecules vary in size, and the smallest ones evaporate at lower temperatures, starting in the high 60s. Buds kept at room temperature in an open container will experience some loss of terpenes. Storing buds in a refrigerator or freezer keeps terpenes in a liquid state, rather than gassing off.
Cannabis can be properly stored in a number of different materials, each with pros and cons that make them more or less suitable depending on the grower’s needs.
Glass makes great, inert, hard, non-biodegradable storage containers. The downside is that most glass jars are clear, and light degrades trichomes—which doesn’t matter if buds are stored in the dark. For storing buds exposed to light, opaque glass is best. Different types of glass are used to store food. The color of the glass determines the type of light and heat that can penetrate the barrier.
Violet glass blocks visible light with the exception of the color violet. It also is semi-permeable to UVA, an infrared light, allowing about 40-60 percent to penetrate, depending on the glass formula and thickness.
Miron Glass, a manufacturer in Germany, claims that this combination of light preserves biological material such as herbs as well as fresh vegetation. The company bases its claims loosely on bio-photons, which is very weak light emitted by all living things.
Its literature claims that even when material is dry, the light that penetrates the glass preserves this energy while forming a barrier to other visible spectrums that can cause deterioration of cannabinoids and terpenes.
Placing a glass or stainless-steel container in a dark space such as a refrigerator closet or dark room will also keep harmful light out. It is highly unlikely that there is much UVA light indoors, so none is passing through. However, visible light is filtered out.
In a controlled experiment, fresh garden tomatoes were placed in a Miron container, a stainless-steel container and a clear-glass container. All were sealed and the clear-glass container was kept entirely in the dark.
When the jars were opened a month later, the tomatoes were still fresh, if a little dehydrated. The containers were closed again and reopened a month later. All three tomatoes had begun molding at similar rates.
Stainless-steel tubs with plastic seals and flip-top locking mechanisms are popular because they’re strong and can be stacked. The metal does not interact with the buds and is impervious to outside air. Stainless-steel containers are an excellent choice for storage.
Cannabis is slightly acidic and lipophilic, so it degrades some plastics. Plastics are stickier than glass or stainless steel. Odorless turkey bags are popular because they contain odors well and are inexpensive. However, they are easily pierced by stems and offer no protection from shaking and movement, which leads to more damage and shake. Five-gallon buckets sealed with toothed, locking airtight lids will protect buds from getting crushed and can be stacked.
A desiccant is a substance that removes moisture from the surrounding air. Desiccants are often found in certain food packages, like those for dried seaweed, and in electronics. Silicon packets, newspaper or anything extra-dry acts as a desiccant and absorbs moisture in a storage container.
Vacuum packaging is popular because it decreases the amount of oxygen present in a storage container. Oxygen is corrosive and degrades the buds’ color. A decreased presence of oxygen also discourages the growth of spoilage bacteria, but not anaerobic bacteria. Anaerobic bacteria thrive in low- and no-oxygen environments that are damp and have food—the buds! Never seal and store wet or damp buds.
Gas-flushed, sealed Mylar bags are excellent packaging for long-term storage. The process flushes the bag with nitrogen and seals it. Unlike oxygen, nitrogen is inert and doesn’t burn. Purging packages of oxygen extends the life of the buds and prevents the growth of mold and discoloration, similar to vacuum sealing. Gas-purged bags are a cornerstone of consumer food-product packaging and are common in snacks like chips and jerky. Some testing labs offer nitrogen bagging services using tamper-proof packaging.
Instead of being prepped and dried, marijuana can be made directly into concentrates or stored undried and “wet” frozen to be used later. This saves energy and labor. With storage, the conversion of the material can be postponed to a more convenient time. Either fresh or frozen buds can be used for bubble, or BHO. First, the chopped buds are brought to near-freezing temperatures. Then agitation from a paint mixer or other tool makes the glands brittle; they break off and are collected in a series of filters that catch different-size glands. When collected, the glands make hash, which can be used in a vaporizer or pipe or as an intermediate for making butane or C02 concentrate. BHO extractors use butane as a solvent to de-cannabinize and de-terpenize the leaf. The result is a very pure dabbable concentrate.
After the Harvest
After the harvest is complete, growers are left with a variety of byproducts. What used to be considered trash is now processed further and enjoyed or sold. The first step is to evaluate and separate the material.
The most efficient way is to sort it during trimming.
The quality of the remaining material is based on the percentage of THC and other cannabinoids it contains. Three types of growth remain after the buds have been removed: popcorn buds (larf), sugar trim and fan leaves.
Stems and woody parts of the plant are not suitable for ingestion since they contain few cannabinoids.
Grades of Trim
Popcorn Buds (Larf)
Buds that receive less light grow smaller and less dense. They are time-consuming to trim and cosmetically undesirable in the market. However, they contain a high percentage of THC and are often used to make pre-rolls or concentrates.
Sugar trim refers to the resin-covered leaves that grow near and often surround the buds. They are cut during manicuring and, other than the buds, contain the most THC in the plant. Sugar trim is used to make extracts such as kief, hash, tinctures and edibles.
Fan Leaves (Sun Leaves)
Although fan leaves contain a third or less of the cannabinoids as sugar trim, processing them may still be worthwhile. Leaves with visible glands are worth keeping. Leaves from immature plants typically have very few glands and do not yield much THC.
Use a magnifying glass or photographer’s loupe for a close-up look at the material. Fan-leaf glands are often small and hug the surface of the leaf, while glands near the flowers are stalked and look like mushrooms with bulbous caps. The latter contain considerably more cannabinoids than the smaller glands.
Male plants also contain cannabinoids. These cannabinoids are strongest at the budding, pre-flowering stage. The sugar leaves—small leaves near the flowers—are the most potent, followed by the younger and then the older fan leaves. Male plants are not prized for resin production and are often removed from the garden and destroyed.
- To use fan leaves in cooking, gently heat them in butter or oil. Use the infused oil in salads or cooking.
- Grind dried fan leaves into fine flour and substitute it for a small portion of regular flour in recipes. To remove the chlorophyll taste, soak the leaves in cool water before drying and grinding. The flour can also be used in making salves and poultices; an easy method is to mix it into an existing topical ointment.
- Juice the fresh leaves. Start by rinsing them and then run them through a wheatgrass juicer. To store for later, pour the juice into ice cube trays and freeze it. The juice is ingested medically and for general health maintenance.
Stems and branches contain little to no usable THC. However, there are several ways to recycle them:
- Chop and use as mulch
- Use as fire kindling
- Carve the large stems
- Use as walking sticks
- Use for craft projects such as papermaking
- Chop finely for superior horse bedding or small animal litter
There are various ways to use the separated trim and maximize crop value. Trim, sugar leaves and popcorn buds can be converted to kief, hash, BHO, tinctures and cooking oils. For the purposes of this book, only safe, at-home extractions are covered. For more in-depth instructions and information on all post-harvest extractions, see the book Beyond Buds, Next Generation: Marijuana Concentrates and Cannabis Infusions, by Ed Rosenthal and Greg Zeman.
When the trichomes are separated from the plant material, they form a pale blond to green powder, known as kief. High-quality golden kief is consumed. Lower-quality green kief, which contains a lot of vegetation, is used for cooking or for further processing.
The blond glands are delicious when smoked fresh and loose and have a lighter, distinctively different flavor than the whole bud. They have not been heated, so the kief has a high concentration of terpenes. Some traditionalists insist that kief is best pressed into hash. It can also be sprinkled over a bowl or joint, or mixed in food. The simplest and most common method of making kief from sugar leaves or popcorn buds is by screening it.
Screening for Kief
Use a fine screen. The size of the openings in the screen determines what size glands and how much residual plant material passes through. The vigor used in rubbing the plant material over the screen has a profound effect on the quality of the final product. Rub gently. More debris is pushed through when the screening is vigorous. Also, sifting the same material a few times yields more kief, but each sift results in a higher proportion of plant mixed with the glands.
Kief or pollen-sifting boxes and screens are good tools for processing small personal-use amounts. They can be as simple as wooden stash boxes with a screen above a pullout drawer to catch the glands that fall off buds from normal handling. Other boxes are made specifically to capture different grades. Use cold buds and trim because cold causes the trichomes to become brittle and break more easily.
Automatic kief makers called Pollinators and pollen sifters use a tumbling action to rub leaves against a screen that separates the glands from the leaves. The rubbings are collected on a bottom plate.
Divide kief processing by time. The highest grade comes from the first minute of rubbing. The material degrades with each processing as the ratio of vegetation to glands increases.
How Water Hash Works
The most common water-hash processing method uses a combination of water, ice and agitation to separate glands from the plant material. Ice, water and plant material are placed in a bucket that has been lined with filtration bags with screens on the bottom similar to the screens used for making kief. The material is agitated to knock the trichomes free. Plant material is trapped and floats in the top bag while the glands, which are heavy, sink to the bottom and are collected in the bags.
Ready-made systems use multiple bags, usually three to seven with various size screens to sort the glands into grades. Unlike kief making, the material is separated in one step rather than through repeated sieving. Usually the material is processed once, although some commercial hashmakers process it a second time to capture more of the THC.
Ice serves a dual purpose: It acts as an agitator against which the plant material rubs, and it makes the material very cold so the glands become brittle. After the material is agitated in ice water, it is allowed to settle. Then the bags are separated, and the glands are removed from each one. They vary in content. Different-size glands have different effects. After water hash is dried, it is ready to smoke.
Water hash varies in color, much like kief. The finest grade is typically a light tan, while the coarser second-tier material is slightly darker and may be a little green from plant-material contamination.
Water hash can be made without bags. Agitate the material in ice and water for 20 minutes. A paint mixer attached to a motor or drill works well. After agitating, most of the plant material floats. Remove it using a colander and cooking spoon. Glands are heavier than water and detach from the vegetation. They sink to the bottom of the container where they form a gray or tan layer. Rinse them from the container and capture them in a coffee filter.
The quality of water hash, especially from the finest-grade material, is impressive. It can test as high as many solvent-extracted hash products: up to 80 percent, although 50 percent samples are more common. The effects produced by water hash depend on the strain and quality of the plants. Processing plant material with water yields hash that has been washed free of some contaminants: green plant matter, dust, dander and some mold, bacteria and chemicals. However, high counts of mold and bacteria are commonly found in tests of water hashes. Perhaps a final rinse in 1 percent hydrogen peroxide water will lower these counts.
Extraction yields 0.5 to 2 ounces (14-57 grams) of hash per pound of plant material, depending on gland density and size.
Hi I just had a quick question about the use of Ozone in a grow room on marijuana plants in the harvesting process. I know that Ozone can damage or kill plants in high concentrations while the plants are still in the growing process but what can you tell me about the use of Ozone on marijuana plants that are in the harvesting stage? any insight into this at all is much appreciated, thank you!
How to tell when it’s time to harvest
wondering how effective storage in a c-vault, inside a freezer would be?
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