How Long Is Weed Good in a Plastic Bag?

Storing weed the right way matters. Get it wrong, and your stash can dry out, lose potency, or even grow mold. No one wants to smoke weak, stale, or musty weed.

Many people keep their cannabis in plastic bags. It’s easy, cheap, and convenient. But is it the best choice? Not really. Plastic bags don’t protect against air, light, or moisture—all things that can ruin your weed fast.

Have you ever opened a bag and found dry, brittle nugs that crumble to dust? Or maybe your weed lost its strong smell and now just seems... off? That’s because poor storage speeds up the aging process.

So, how long is weed good in a plastic bag? And what can you do to keep it from going bad?

In this article, you’ll learn:

• How long weed lasts in a plastic bag before losing quality.

• The factors that speed up weed degradation.

• Better storage alternatives for long-term freshness.

Let’s start with the big question.

How Long Is Weed Good in a Plastic Bag?

Weed stored in a plastic bag won’t stay fresh for long. At best, you have about one to two weeks before it starts losing quality. After that, it dries out, loses potency, and may even develop a stale or grassy smell.

Why does this happen so fast? Plastic bags offer almost no protection from air, light, or moisture—the three biggest threats to cannabis freshness.

• Air exposure: Too much oxygen speeds up THC degradation. Over time, THC converts into CBN, a cannabinoid that makes you sleepy but won’t get you high.

• Light exposure: UV rays break down cannabinoids and terpenes, which leads to weaker and less flavorful weed.

• Moisture Problems: Plastic bags don’t regulate humidity. Too much moisture invites mold; too little makes your weed bone-dry.

If you're wondering how long weed lasts in a Ziploc, the answer is similar. Ziploc bags offer slightly better sealing than thin plastic bags, but they still don’t protect against air, light, or humidity—so degradation happens quickly.

Timeline for Weed Stored in a Plastic Bag

• First few days: Still fresh, but some terpenes may escape if the bag isn’t sealed properly.

• 1-2 weeks: Noticeable dryness begins. The aroma fades, and the texture becomes brittle.

• 1 month: Significant loss of potency. The weed may taste harsh or unpleasant when smoked.

• 2+ months: Weed becomes overly dry, harsh, and possibly moldy if exposed to humidity.

Does Temperature Matter?

Yes! 

Where you store your plastic bag makes a huge difference.

• Cool, dark places (best case scenario): Weed lasts a little longer—maybe three to four weeks—before major degradation.

• Warm, humid areas (worst case scenario): Weed can become dry, stale, or moldy in under a week.

If you want to extend freshness, learning how to store marijuana properly is key. The right storage method can prevent THC breakdown, keep moisture levels stable, and stop mold from forming.

Factors That Affect Weed Freshness in a Plastic Bag

Not all weed goes bad at the same rate. Several factors speed up—or slow down—how quickly your stash loses potency, smell, and smoothness. 

If you’re keeping weed in a plastic bag, here’s what you need to watch out for.

1. Air Exposure - THC Breaks Down Over Time

Plastic bags aren’t airtight. This means oxygen slowly seeps in and starts breaking down THC. Over time, THC converts into CBN, a compound that’s far less potent. Ever smoked old weed and felt more sleepy than high? 

That’s CBN at work.

More air also dries out the bud, which makes it brittle and harsh to smoke. Without proper sealing, your weed will go from fresh to stale within weeks.

2. Humidity - The Mold vs. Dryness Problem

Moisture control is one of the most important factors to consider. 

Too much humidity can turn your weed into a breeding ground for mold, while too little will make it dry and harsh.

• Too humid (above 65% RH): Weed may feel sticky or spongy, and mold can start forming.

• Too dry (below 55% RH): Trichomes (the resin glands containing THC) start breaking apart, which reduces potency and flavor.

Plastic bags don’t regulate humidity. 

That means your weed is at the mercy of the air around it.

3. Light Exposure - The THC Killer

Sunlight and even indoor lighting can degrade cannabinoids fast. UV rays break down THC and other compounds, which leaves you with weak, low-quality bud.

If you keep weed in a plastic bag, avoid placing it near windows, lamps, or anywhere light can reach it.

4. Temperature - Heat Speeds Up Degradation

High temperatures accelerate THC breakdown. If you store a plastic bag of weed in a warm car or a stuffy drawer, it’ll dry out faster and lose potency.

For best results, store your weed at room temperature (60–70°F) in a dark place. Anything hotter, and it won’t stay fresh for long.

5. Quality of the Plastic Bag - Not All Are the Same

Thin plastic bags let in more air, which makes them worse for long-term storage. Some also generate static, which can strip trichomes from the bud.

If you have no choice but to use a plastic bag, go for a thicker, resealable one. Even then, it’s far from ideal.

How To Tell If Your Weed Has Gone Bad

Not sure if your weed is still good? Old or poorly stored cannabis doesn’t always look moldy or rotten, but it definitely won’t be as enjoyable to smoke. Here’s how to check if your stash has gone bad.

Smell Test - The Nose Knows

Fresh weed has a strong, distinct aroma—earthy, citrusy, piney, or skunky, depending on the strain. If your weed smells faint, stale, or like hay, it has lost most of its terpenes.

A musty, damp, or ammonia-like smell? That’s a major red flag for mold or mildew. If your weed smells off, don’t risk smoking it.

If you're unsure about how long you can safely store cannabis before it starts losing quality, check out this in-depth guide on how long you can store weed.

Texture - Too Dry or Too Moist?

Touch your buds. Good weed should be slightly sticky and firm but still break apart easily. If it’s too dry, it’ll crumble into dust—meaning it has lost most of its moisture and potency.

On the other hand, if your weed feels damp, spongy, or unusually soft, it may have absorbed too much moisture. Mold and bacteria thrive in humid conditions, so toss it if it feels too wet.

Appearance - Signs of Mold or Discoloration

Look closely at your weed under good lighting. Mold often appears as white, gray, or fuzzy patches. Other warning signs include dark spots, excessive yellowing, or web-like growth.

If you’re unsure, break open a bud. If you see anything suspicious inside, it’s best to throw it out.

Smoke Quality - Harsh, Stale, or Off-Tasting?

If your weed looks fine but tastes harsh, flat, or chemically off, it has probably degraded. Old weed won’t get you as high and can make for a rough, unpleasant smoke.

Best Storage Alternatives to Plastic Bags

If you want to keep your weed fresh for as long as possible, ditch the plastic bag. 

There are much better ways to store cannabis that help preserve its potency, aroma, and moisture levels. 

Here are the best alternatives.

Glass Jars with Airtight Seals - The Gold Standard

A glass jar with an airtight lid (like a mason jar) is one of the best ways to store weed. It locks out excess air, which prevents oxidation and THC degradation. 

Unlike plastic, glass doesn’t generate static, so your trichomes stay intact.

For best results:

• Use a small jar that fits your weed snugly to limit extra air.

• Store it in a cool, dark place to avoid light and heat damage.

• Keep the lid sealed tightly to maintain freshness.

One great option is the Ludist Stash Jar. 

Made from durable borosilicate glass with an airtight aluminum lid, it prevents air and moisture from ruining your weed while keeping smells contained. 

Plus, its sleek design fits seamlessly into any space.

If you're wondering how long weed lasts in an airtight jar, the answer depends on storage conditions. With proper sealing and humidity control, weed can stay fresh for months—sometimes even a year.

You might also be wondering—do mason jars hold the smell of weed? The short answer is yes, but only if they have a proper seal. A tightly closed jar will keep odors contained while maintaining freshness. 

Learn more about whether mason jars are smell-proof here.

Vacuum-Sealed Bags - Good for Short-Term Storage

Vacuum-sealed bags remove most of the oxygen and as a result, slow down THC breakdown. 

While better than a regular plastic bag, they aren’t perfect for long-term storage. Over time, the lack of airflow can cause weed to lose its flavor and aroma.

Also, vacuum-sealing compresses the buds, which can crush trichomes and reduce potency. If using this method, choose a gentle vacuum seal setting.

Humidity-Controlled Containers - Ideal for Moisture Balance

Cannabis stays freshest at 55–62% humidity. 

Too dry, and it loses potency. 

Too humid, and mold becomes a risk.

Specialized cannabis storage containers (like Boveda or CVault containers) regulate humidity using built-in packs. These containers keep your weed at the perfect moisture level for a smooth, flavorful smoke.

Dark Storage Boxes - Protect Against Light Damage

Since UV rays degrade THC, dark, opaque containers help maintain potency. Some cannabis storage boxes are designed to block out light while providing odor control and humidity regulation.

A solid choice is the Ludist Stash Box, which offers airtight, smell-proof storage with thoughtful compartments for organizing all your smoking essentials. 

The built-in rolling tray and durable wood design make it both functional and stylish.

Final Tip: Avoid storing weed in the fridge or freezer. Temperature changes cause condensation, which can lead to mold.

Final Thoughts

Weed stored in a plastic bag doesn’t stay fresh for long. Air, light, humidity, and temperature changes quickly degrade its potency, flavor, and smoothness. After a few weeks, your stash can dry out, lose its aroma, or even develop mold.

To keep your weed fresh longer, proper storage is key. 

A glass jar with an airtight seal, like the Ludist Stash Jar, locks in freshness while keeping odors contained. 

For a more organized, smell-proof solution, the Ludist Stash Box provides airtight storage with compartments for all your smoking essentials.

Ditch the plastic bag and invest in better storage. Your weed—and your lungs—will thank you.