How Long Do Cannabis Seeds Last?

How long do marijuana seeds last? While buying cannabis seeds in bulk is an excellent way to save money, you may not always be able to plant them immediately. 

Although it’s possible to keep them viable for a long time, knowing how to do it is critical. Discover ways to extend their lifespan and preserve them for multiple cultivations.

Let’s dive in.

Factors affecting the lifespan of cannabis seeds

While there’s information on how long it takes to grow weed, there’s no definite answer on marijuana seeds’ lifespan. What cultivators know is that they last many years with proper care. 

Note that all weed seeds aren’t equal. Some are larger or more hardy than others. Their viability depends on several factors, including:

• Genetics

• Storage

• Light

• Heat

• Humidity

• Oxygen supply

Let’s review the preservation methods. 

Genetics

Besides choosing specific types, like feminized seeds, the strain and genetics play a critical role in their ability to survive.

It’s vital to buy them from trusted businesses like us to ensure you get quality. Premium-grade weed seeds last longer than poorer ones.

Storage

How long are cannabis seeds viable? It depends on how you store them.

A general practice is to keep weed seeds in a cool, dark place to protect them from mold and pathogens. Inspect them regularly, as long periods in storage may result in some that won’t sprout. This number increases as time goes by.

When learning how to store cannabis seeds, some cultivators refrigerate them. The lower temperature is ideal for keeping them viable for a long time.

Freezing seeds is an option but isn’t necessary. The rationale is that you don’t open your freezer as frequently as your fridge, reducing temperature fluctuations and light exposure.

Whatever method you choose, handle the weed seeds carefully to avoid crushing or damaging them. Some growers place them in containers with cotton wool to minimize movement and contact with each other.

Established seed banks (like us) have excellent storage facilities and ship your order in a manner that protects the contents from damage.

Light

Besides quality and storage, light is vital to determine how long marijuana seeds last. While autoflowering seeds grow into plants that don’t depend on a specific illumination cycle to start flowering, it signals them to prepare for germination. 

Preventing premature light exposure is critical. If the seeds’ chemical process begins and it’s not sprouting time, they may not pop later.

Although seeds have shells protecting them from luminescence, storing them in the dark prevents such accidents. Keep them in their packaging or a non-transparent container, such as a mason jar. 

Temperature

Guides on how to germinate marijuana seeds advise storing them away from heat as high temps signal that it’s sprouting time. Although you may keep them at room temperature, a cooler location within 42–46°F is ideal. 

Avoid exposing seeds to fluctuating conditions as they may deplete their nutrients before germination.

Humidity

How long do weed seeds stay good? Maintaining humidity levels may extend their lifespan. Moisture signals germination is about to start, but rot risk increases in damp conditions. 

The ideal environment is dry with 8–10% relative humidity (RH). Higher levels cause seeds to perspire. Avoid 40–60% RH unless you’re ready to germinate.

Observe the following moisture ranges to protect your stocks:

• Below 20%: This condition is too dry and may cause fungi, sweating, and drying out.

• 20–30%: The ideal level to store seeds.

• 40–60%: The optimum germination range.

• 75–100%: At these high levels, your seeds may drown.

Ensure your storage space has sufficient ventilation by keeping windows open. Invest in a dehumidifier, if necessary.

Oxygen supply

As a lack of fresh air prevents sprouting, vacuum-sealed containers are perfect for storing marijuana seeds. 

When you get your order from us, put the package in a mason jar. Place it inside a fridge, preferably one you don’t frequently use, to avoid temperature and humidity fluctuations when opening the door.

How long do cannabis seeds last with proper care?

Those new to growing cannabis may want to know how long seeds last before they go bad under optimal conditions. It depends. They typically survive 1–2 months if kept at room temperature, but cultivators claim they can last as long as five years.

To extend your seeds’ life, refrigerate them. Maintain optimal humidity and temperature levels as fluctuations severely risk their viability.

We recommend you use your supply early, as the longer you keep your seeds, the higher the risk of them not germinating [to learn more, check our article about "cannabis seeds not germinating"].

Are cracked marijuana seeds good for germinating?

The question, “How long do cannabis seeds last?” refers to the time before they germinate. An excellent way to identify the viable ones is by inspecting them.

If you notice tiny holes or cracks on the surface, it’s an indication that the seed isn’t likely to sprout. The openings on the shell expose the inner genetic material, causing damage that affects its germination ability.

Other viability signs to look for are the color and texture of the seed. If it’s firm, with an external dark coloring and waxy coat, it’s likely to pop. 

A rule of thumb is that the usable ones are usually brown, black, or gray and are spotted or striped. A lighter shade means the seed is old and won’t germinate. As strains are unique and may have milder hues, find out what your choice should look like.

Another sign of how long cannabis seeds last is the time it takes for the shell to change its structure. Gently squeeze it between your fingers; if it’s brittle and crushes, it likely won’t germinate.

A simple test is to drop the seeds into a glass of warm water and wait a few hours. Those ready for germination typically sink to the bottom, while dead ones remain floating. Only perform this trial on those you’re preparing to sprout as fluids trigger the process.

That’s how to tell if weed seeds are good. What do you do with those that aren’t usable, so they don’t go to waste? Crush them and add them to the soil. As they rot, they provide the plant with nutrients.

How to keep your marijuana seeds viable longer

How long do weed seeds stay good? Depending on their care, they can last from a couple of months to more than five years.

Quality seeds with excellent genetics remain viable for a very long time with proper conditions. Keep them in a cool, dark, and dry storage space and maintain optimal temperature and humidity levels with no fluctuations.

Browse our website for handpicked, premium-grade cannabis seeds and more growing tips.

About the Author: Kyle Kushman

Kyle Kushman is a legend in the cannabis community. He is the modern-day polymath of pot: cultivator, breeder, activist, writer, and educator. After winning no less than 13 Cannabis Cups, there’s nothing this guy doesn’t know about indoor growing - he’s been there, done it, and is still doing it to this day!