How to Tell If Cannabis Is Fresh and How to Preserve It

Like any other organic product, cannabis naturally degrades over time, especially if stored in conditions that aren’t ideal for preserving plant material. Storing cannabis in a humid environment can quickly lead to the growth of mold colonies on the product’s surface. Even slightly moldy buds are not recommended for use: while burning mold may not noticeably affect a healthy person, these particles can trigger allergic reactions or other side effects in people with chronic health conditions. Additionally, spoiled cannabis loses much of its psychoactive properties and develops a strong, unpleasant taste and odor—another good reason to avoid using it.

How Long Does Cannabis Stay Fresh?

With proper curing and storage (meaning the product is dried and cured for a few days or weeks, then placed in a tightly sealed vacuum container and kept in a cool, dark place), cannabis buds can stay fresh for 6–12 months from harvest. After this period, natural decarboxylation processes begin in the plant tissues, causing active compounds like THC and CBD to gradually break down into simpler substances that lack the desired therapeutic or recreational effects. One study on recreational cannabis quality (specifically THC concentration) found that, even with ideal storage and curing, the product naturally loses up to 16% of its active compounds after one year. The rate of natural decarboxylation only increases over time, turning even the best-preserved cannabis into useless dust within 3–4 years. Terpenes and flavonoids, which give cannabis its aroma and flavor, evaporate even faster during long-term storage. So, if you plan to store buds for a long time, keep this in mind: even if the psychoactive effects remain after a year, the taste will likely be replaced by a straw-like flavor and aroma, making long-term storage less appealing.

In any case, both overly moist and very dry buds are warning signs. If the product is too moist, check for mold. If it’s too dry, smell it and try to break it apart. Shiny mold spots on the surface, a lack of aroma, or a crumbly, dusty texture all indicate spoiled cannabis, which should not be used.

How to Identify Old or Spoiled Cannabis

There are several external factors to look for when checking cannabis quality:

Smell

Smell is often a better indicator of quality than appearance. This is especially true for strains with a strong, memorable aroma typical of their type or hybrid family. Any sharp changes in the strength or notes of the aroma can indicate old or spoiled product. Dried-out buds usually have little to no smell or smell like hay, while moldy buds have a strong, pungent odor, sometimes with a rotten note.

Keep in mind that some strains, like Skunk or Cheese, are bred for their unique and strong aromas, which may seem odd or harsh to beginners, even if the buds are high quality.

Appearance and Texture

Quality can also be determined by appearance and texture. Good cannabis doesn’t crumble to pieces when touched (as old buds do) and doesn’t feel spongy or wet (as with rotting buds). Mold colonies are easy to spot: look for white or dark fuzzy patches on the surface or inside the bud. Old, dried-out cannabis often looks dull or rusty, making it easy to visually identify bad product.

Feeling Unwell After Use

If you accidentally use spoiled cannabis, you may notice mild symptoms a short time later. For healthy people, mold can cause mild nausea or, in rare cases, vomiting. For those with allergies or respiratory infections, mold particles can trigger asthma attacks or throat irritation. Dried-out cannabis usually doesn’t cause such strong reactions, since it contains almost no active compounds. The main side effects are unpleasant taste and aroma, and possibly increased fatigue or drowsiness due to THC metabolites left in the plant after long-term decarboxylation.

How to Spot Mold on Cannabis Buds

Mold colonies aren’t always easy to see. If the infection is recent, whether on freshly harvested or already cured buds, mold can hide in crevices where moisture lingers. That’s why it’s important to thoroughly dry and inspect your harvest before storage. The most common infection is powdery mildew and similar fungi. When checking for mold, look for clusters of whitish fuzz, sometimes forming black dots (unlike the usual clear trichomes), and for pungent, musty aromas reminiscent of wet grass or hay.

Even if only a small part of the bud is affected, it’s best to avoid using it to prevent illness or complications. At most, you might risk using parts of the bud that show no signs of mold, but never use any fragments that clearly have mold colonies. Consuming moldy cannabis almost always leads to nausea or feeling unwell soon after use.

People with chronic illnesses, especially respiratory conditions or immune system issues, should completely avoid moldy cannabis. While others may only experience mild symptoms or allergic reactions, those with compromised immune systems could face serious health risks, even life-threatening ones. In short, if the product looks suspicious or smells strange, it’s best to avoid it for your own health.

Proper Long-Term Cannabis Storage

Four main factors affect cannabis preservation: air exposure, humidity, temperature, and sunlight. Air and temperature directly impact the preservation of active compounds: the less oxygen and the lower the temperature inside the storage container, the better. Direct sunlight also speeds up the natural decarboxylation of cannabinoids and terpenes. Humidity, as mentioned earlier, encourages mold growth (which is also why freezing is not recommended, as condensation can cause rot).

For reliable long-term storage, keep cannabis in a tightly sealed, vacuum container in a cool, dark place.

Storing Cannabis in Glass Jars

The most common, affordable, and reliable way to store cannabis long-term is in regular glass jars, like those used for jams and pickles. Unlike plastic, glass doesn’t contain organic compounds that can leach into cannabis during storage. Glass also doesn’t create static electricity, which can cause trichomes to stick to the container walls. Finally, these jars are designed for vacuum storage, allowing you to remove air for long-term preservation (over one month).

Recommended Humidity and Temperature for Cannabis Storage

It’s important to maintain optimal humidity to prevent both mold and premature drying. Through trial and error, cannabis growers have found that a humidity level of 59–63% is ideal for long-term storage in standard glass jars. Avoid freezing cannabis, as condensation can form and cold can cause trichomes to break off. The best storage temperature is around 77°F (25°C), with only minor fluctuations. Always keep cannabis out of direct sunlight, as light accelerates cannabinoid decarboxylation in the buds.