How Long Does Marijuana Stay Good For?

How Long Does Marijuana Last?

A question came up recently in a court preceding asking how long does marijuana stay good for? Why is this even important to law enforcement? Many dealers in an effort to avoid responsibility for their actions will say that they are saving up their marijuana for use later. It’s an old story, but one that would need to be addressed in some form during your initial investigation to make court go a little smoother.

So, how long does marijuana keep? So I queried informants on how long marijuana keeps for them. I have also asked informants over the past two decades how much marijuana they use per day. Some use every day, some use only a few times per week or a few times per month. So, let’s break it down.

Marijuana Storage Basics

In order to understand how long marijuana keeps, we need to understand the forms of storage that users will employ and how it survives in any given environment. Mildew and mold are big concerns for people that grow marijuana and that use marijuana. Mildew and mold thrive on marijuana when the temperature is between 77 and 86 degrees. So, if marijuana is stored in an area with that type of temperature, it could be quite damaging to marijuana. Excessive heat can dry out the cannabis and cause further damage. Excessive cold, such as marijuana stored in a refrigerator or freezer can also damage marijuana and degrade the high a user wants. Exposure to air is another factor.

So keeping marijuana in a cool dry place is optimal for keeping marijuana for longer storage. Keeping it in mason jars that are sealed is much better than keeping it in sandwich bags.

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Don’t Forget the User’s Consumption of Weed

Myself and other instructors have been asking our informants for years how much marijuana they smoke a day. Currently, most informants are telling us that they smoke anywhere from a gram to a gram and a half a day. With that said, that means that it would take a user 302 days to go through one pound of marijuana (roughly 10 months). If a person had 10 pounds of marijuana and said that he was storing it for his own personal use, he would have in the neighborhood of 8 years of marijuana on hand. Would the marijuana last 8 years? I’m sure the potency would be significantly degraded. Would a tobacco smoker smoke a 8 year old cigarette?

 What Do the Studies Say?

I found several studies that had to do with marijuana degradation. Here are some of the highlights:

Constituents of Cannabis sativa L. XIII: Stability of dosage form prepared by impregnating synthetic (–)-delta 9-trans-tetrahydrocannabinol on placebo Cannabis plant material.
Lewis GS, Turner CE
J Pharm Sci 1978 Jun;67(6):876-8


“Synthetic (–)-delta 9-trans-tetrahydrocannabinol impregnated on placebo Cannabis decomposed only 6.3% after being stored for 1 year at –18 degrees. Storage at 5 degrees and room temperature under various conditions led to severe decomposition. The amount of cannabinol observed when (–)-delta 9-trans-tetrahydrocannabinol decomposed indicates that cannabinol is not the only decomposition product.”

The stability of cannabis and its preparations on storage
Fairbairn JW, Liebmann JA, Rowan MG
J Pharm Pharmacol 1976 Jan;28(1):1-7

“Solutions of pure cannabinoids, nine samples of herbal and two of resin cannabis (one freshly prepared) were stored in varying conditions for up to 2 years. Exposure to light (not direct sunlight) was shown to be the greatest single factos in loss of cannabinoids especially in solutions, which should therefore be protected from light during analytical and phytochemical operations. Previous claims that solutions in ethanol were stable have not been substantiated. The effect of temperature, up to 20 degrees, was insignificant but air oxidation did lead to significant losses. These could be reduced if care was taken to minimize damage to the glands which act as “well filled, well closed containers”. Loss of tetrahydrocannabinol after exposure to light does not lead to an increase in cannabinol, but air oxidation in the dark does. It is concluded that carefully prepared herbal or resin cannabis or extracts are reasonably stable for 1 to 2 years if stored in the dark at room temperature.”

Wrapping This Up in Your Investigation

Make sure that during your investigation, you ask the suspect how they ingest marijuana. Do they smoke it? Do they eat it? Also document how all of the marijuana is stored. Later in court, the expert testifying can lay out exactly what they think the marijuana is being used for; sales or storage for use later on.

Author: Keith Graves
Keith is a retired Police Sergeant and worked in the San Francisco Bay Area for 29 years. Keith was named as California’s Narcotics Officer of the Year and is a prior winner of MADD’s California Hero Award. He has years of experience as a Narcotics Detective and a Narcotics Unit Supervisor and is a Drug Recognition Expert Instructor (IACP #3292). Keith teaches both the DRE course and the Drug Abuse Recognition Course and has taught at the Police Academy. He has developed several drug courses for the California Narcotics Officers Association, California POST and California Colleges and currently consults POST on drug investigation procedures. Keith has held other assignments besides narcotics including Training Sergeant, Patrol Sergeant, COPPS Officer, Traffic Officer, and 20 years as a SWAT Team member and Sniper Team Leader. Keith has taught thousands of officers and businesses around the world about drug use, drug trends, compliance training and drug investigations. He is recognized as an international drug expert and has testified as an expert in court proceedings on drug cases, homicide cases and rape prosecutions. Keith earned a BA in Business Management from Saint Mary's College of California and a MA in Criminal Justice. Keith is the Founder and President of Graves & Associates, a company dedicated to providing drug training to law enforcement and private industry.

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