How To Store Cannabis Seeds

Everything you need to know about preserving and extending your marijuana seed shelf life.  Guest Post written by Kimberlee Morrison.

Cannabis seeds are alive.
This might seem obvious, but it’s probably the biggest thing novice growers forget. 

Not only is the seed alive, it’s the beginning of everything: Every new plant; every harvest. Whether you’re a hobbyist or a pro grower, the quality of your seeds determines how your cannabis plants develop—and it can impact your yield when it comes time to harvest.

So how you store and preserve your marijuana seeds is crucial.

Storing cannabis seeds is a way to keep them viable over an extended period of time. Proper storage can make the difference between seeds with high germination rates, and seeds that become diseased, rot, or die before they have a chance to achieve their germination potential.

When storing cannabis seeds you want to prevent germination, while also creating conditions that could maximize germination when the time comes. Light, heat, and moisture all signal to the seed it’s time to sprout and grow.

The good news is that storing marijuana seeds is pretty simple: Just keep them in a cool, dark, and dry place.

Let’s Talk Storage Containers

Temperature, humidity and light are the key factors to control for storing your cannabis seeds. However, before you even get there, you’ll have to pick storage containers. 

If you’re not using your seeds right away, it’s best to keep them in the original storage container and simply find a cold dark place. Some growers store their cannabis seeds in plastic containers or even glass tubes.

For short term storage, an envelop could be a good option. However, for long term storage, the best storage containers are opaque, airtight, and made from a single material. For instance, you don’t want to choose a glass jar with a plastic lid. Likewise, you probably don’t want to use a plastic jar with a metal lid. 

Mixed material containers aren’t ideal because the different materials are affected differently by temperature changes, which means less control over the storage environment. And ultimately you want as much environmental control as possible. 

Plastic is slightly porous and doesn’t meet the airtight requirement for long term storage, and airtight glass containers are typically mixed materials. 

One of the best storage solutions is a vacuum sealed mylar bag: It’s a single material, it’s opaque, and the vacuum seal will prevent humidity. Glass containers with rubber stoppers are the one exception to the mixed media rule, and are a recommended option for seed storage.

Whatever you choose to store your cannabis seeds in, include something to keep the humidity levels low like a silica packet or uncooked rice, wrapped in cotton or paper. 

Speaking of Humidity

Humidity is one of the most important variables to get right when storing and preserving cannabis seeds. If the humidity is too high, the seeds might begin to germinate before you’re ready. Or worse, the hard outer shell on your seeds might begin to soften, reducing their viability. 

You don’t want the humidity too low either. If the humidity is too low, your seeds will start to dry out and become desiccated. Remember, your cannabis seeds are alive, and every living organism needs some amount of moisture to stay alive. 

The ideal humidity for long term storage is somewhere in the range of 25-40%—even then, 40% might be pushing it. 

The good news is that you don’t have to get any special tools for measuring humidity. Since modern refrigerators are so dry, if you store your cannabis seeds in the fridge, the humidity level will probably be just fine.

Temperature Control

Temperature is another variable you want to control when storing marijuana seeds. The key thing to remember here is that you want to maintain a consistent cool temperature.

A dark cupboard or drawer might be a good enough option for short term storage. However, if you live in a place with fluctuating temps between the day and evening, this won’t be an adequate solution even in the short term. 

You can extend your marijuana seed shelf life by storing them in the fridge. Just as the fridge helps reduce excess humidity, it’s also a good place to store cannabis seeds because the temperature will stay consistently cold. 

Sometimes the freezer is recommended as a place for storing seeds. Be careful with this option as seeds could become dry and brittle when frozen.

Avoid the Light

The final of the big three control variables for storing cannabis seeds is light. Light is a signal to seeds that it’s time to grow and become a plant. 

If the plan is short-term storage in a closet or drawer, light might not be that big of an issue. If you’re going with this option, make sure you choose the darkest, least frequently trafficked space in your home or nursery.

Again, room temperature is not always ideal even for short-term seed storage. Fridge storage gives you better temperature control. The challenge here is that unless you have the right storage container, your seeds could be exposed to the light every time someone opens the refrigerator.

The best place to start when trying to limit the amount of light your cannabis seeds are exposed to is choosing an opaque container. You can buy Mylar bags on Amazon, just make sure you get the ones without the clear window.

If you’re choosing glass for your storage, you’ll want to get amber or cobalt colored glass to limit light exposure. The alternative could be to wrap glass jars in something opaque and call it a day. 

Enjoy the Experimentation

Treat the growing and cultivation of cannabis as a sort of scientific experiment. Even deciding how to store you seeds can be part of that process. 

If you find that when your seeds don’t germinate or yield the desired harvest, play with the variables to get the conditions just right. If your seeds seem too dry, check that your container is actually airtight. If your seeds seem to sprout too early, check the temperature and humidity levels. 

If you’re storing seeds in the freezer and find that the outer layer is cracked when it’s time to germinate, that’s a sign the freezer isn’t a great storage option. You might even find that different seed strains respond differently to the same environment. 

This is a long-tail experiment. Pay close attention to what doesn’t work and what does, then try to reproduce the conditions that seem to produce the healthiest seeds.