The answer depends on what you’re really asking. A marijuana high from smoking lasts roughly 1 to 3 hours, while edibles can keep you feeling effects for 4 to 8 hours. If you’re wondering how long marijuana stays detectable in your body, that ranges from 24 hours in saliva to 90 days in hair. And if you’re growing or storing it, those timelines stretch even further.
How Long the High Lasts
When you smoke or vape marijuana, THC reaches peak levels in your blood within about 10 minutes. The high typically lasts 1 to 3 hours, though some residual effects like drowsiness or mild fog can linger a bit longer. Smoking and vaping produce nearly identical absorption profiles, so the experience is comparable between the two.
Edibles are a different story. Because THC has to pass through your digestive system and liver before reaching your bloodstream, peak concentrations are delayed by 2 to 4 hours. The trade-off for that slow ramp-up is a longer, more sustained effect that can last 4 to 8 hours total. This delay is also why people accidentally take too much: they feel nothing after an hour, eat more, and then both doses hit at once.
How Long THC Stays in Your System
THC doesn’t leave your body when the high wears off. It gets stored in fat tissue and released gradually, which is why detection windows vary so dramatically based on how often you use it.
Urine Tests
Urine testing is the most common screening method, and detection times scale with frequency of use:
- One-time use: up to 3 days
- Moderate use (about four times a week): 5 to 7 days
- Daily use: 10 to 15 days
- Heavy, prolonged use: 30 days or more
These ranges aren’t exact for every person. THC is fat-soluble, so your body fat percentage, metabolic rate, hydration level, and overall health all influence how quickly you clear it. Someone with a higher body fat percentage will generally retain THC metabolites longer than someone leaner, even at the same usage frequency.
Saliva and Blood Tests
Saliva tests detect marijuana for up to 24 hours after use, making them useful mainly for identifying very recent consumption. They’re increasingly used in roadside testing for impaired driving. Blood tests have a similarly short window, typically picking up THC for only a few hours to a couple of days, since THC moves out of the bloodstream and into fat cells relatively quickly.
Hair Follicle Tests
Hair testing captures the longest window. The standard approach takes a 1.5-inch sample from near the scalp, and since hair grows at roughly half an inch per month, that covers approximately 90 days of history. When the sample is taken from slower-growing body hair, like from the armpit, the detection window can extend up to a full year.
How Long Marijuana Stays Potent in Storage
If you’re holding onto flower or other cannabis products, potency declines over time. At room temperature, THC degrades at a rate of about 3% to 5% per month. That means after a year of sitting on a shelf, you could lose roughly half the original THC content.
Light and heat accelerate the breakdown. Research tracking cannabis stored over four years found that degradation was fastest during the first year, and samples exposed to light at room temperature lost potency significantly faster than those kept in darkness at cooler temperatures (around 40°F or 4°C). Over the full four years, nearly 100% of THC had degraded under standard storage conditions. As THC breaks down, it converts into a different compound that produces little to no psychoactive effect, so old marijuana won’t get you as high and may just make you sleepy.
For the longest shelf life, store cannabis in an airtight container in a cool, dark place. A glass jar in a closet or drawer works well. Avoid plastic bags, which build static and can pull off the tiny resin glands where THC is concentrated.
How Long Marijuana Takes to Grow
From seed to harvest, a marijuana plant takes anywhere from 9 weeks to over 6 months depending on the variety and growing method.
The growth cycle breaks down into four stages. Germination takes 2 to 10 days, followed by a seedling phase of 1 to 3 weeks. The vegetative stage, when the plant focuses on building leaves and stems, lasts 3 to 15 weeks for standard (photoperiod) varieties. Most indoor growers keep this phase to about 4 to 6 weeks, though techniques like screen-of-green training may push it to 15 weeks for larger yields. The flowering stage, when buds develop, runs 7 to 14 weeks. Fast-finishing indica strains can wrap up flowering in 7 weeks, while slow-blooming sativa-dominant strains may need 14.
Autoflowering varieties skip much of this complexity. They transition from vegetative growth to flowering on their own internal clock rather than responding to light cycles, and the fastest autoflowers can go from seed to harvest in as little as 9 weeks. Standard photoperiod strains grown indoors typically take 3 to 5 months total, while outdoor grows are tied to the natural growing season.