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How to harvest and store cannabis seeds

A Seed Saved: How to Harvest & Store Plant Seeds

Preserving seeds successfully requires some trial and error, but the process can be fun and rewarding. Growing plants from seed is a nice way to re-create a gardening success, share your carefully cultivated good fortune with others or just save some money. Seeds may look tough and self-contained, but they’re designed to react to the environment around them. Here’s a few things to keep in mind when handling seeds that haven’t made it into the ground yet.

Planting a seed where you—not nature—decides is a powerful activity. Vast cities have sprouted near-rich farmlands, and whole cultures have revolved around the dynamic contributions of specific plants to human life and culture. All of that would have been much more difficult, if not impossible, without the ability to harness the vitality and mystery of the humble seed.

This Isn’t Your Grandma’s Seed Stock

Saving seeds at home used to be a much more common activity than it is today. During the first half of the 20th century, it wasn’t unusual for families to maintain backyard gardens containing heirloom, open-pollinated plant varieties. In fact, in 1943, at the height of the Second World War, an estimated 40% of produce consumed was grown in victory gardens located primarily on private lands. Seeds for those vegetable gardens were probably sourced locally and later harvested from those backyard gardens.

Although times have changed, growing produce and other plants at home has seen a resurgence during the last decade or so. Is preserving seeds a simple process? Sure, it can be. But there are more factors to consider than there were 70 years ago. Scientists have been hard at work tinkering with plant genetics, which means there are lots of hybrid plants available that may look and taste great but not reproduce true to the original plant. Part of the art of saving seeds is recognizing which ones are good candidates for preservation, and which aren’t.

Natural Selection Isn’t Just About the Birds and the Bees

Preserving seeds from your best plants is a good way to cultivate strains that are well-adapted to your specific growing conditions, indoors and out. It’s natural selection, with a little friendly encouragement. You don’t need to be a geneticist to do it, either. The seeds you choose to preserve and plant later are probably from the hardiest plant specimens. When you save those plant seeds, you preserve the very traits new plants need to survive in your landscape, greenhouse or grow tent.

A Seed-Saving Primer

The conditions you need for good seed germination (warmth and moisture) are the opposite of what you need for good seed preservation. Seeds may look tough and self-contained, but they’re designed to react to the environment around them. When you remove enough moisture and keep them chilled, they stay dormant, waiting for conditions to improve. Some experts believe a seed that’s kept dry enough and at a consistently cool temperature can last a decade or sometimes much longer. For the home grower it can vary, but a good general rule is high-quality seeds should last two to three years if stored carefully. Larger seeds will typically remain viable somewhat longer than smaller seeds. Here are some important steps for saving seeds for future use, trade or sale.

Avoid hybrid seeds – With hybrid seeds, what you see isn’t necessarily what you get. Hybridization is a complex process in which two separate-but-stable plant strains are cross-pollinated to produce a third plant variety that hopefully exhibits the best characteristics of both parent plants. This second generation plant is typically referred to as an F1 hybrid. When it matures and sets seed, the seedlings may be more like one of the grandparent plants, or could exhibit completely unexpected and unwelcome characteristics. If you’re a gambler, go ahead and give hybrids a try. If not, check the labeling on the plants you purchase to make sure they are heirloom stock or open-pollinated cultivars.

Choose open-pollinating plants for seed stock – The term open-pollinated can be somewhat deceptive. It sounds like a random process that can lead to more chaos and potentially bad seedlings than a hybrid cross. It turns out nature is pretty clever, though. Open-pollinated plants, or plants that have developed in nature over time without human intervention, produce reliably consistent results. Generation after generation, these seeds will produce plants similar to the parent plant. This makes them excellent candidates for future cultivation. The one exception is when an open-pollinated plant cross-pollinates with a closely related plant. This can sometimes occur when plants from the same genus and species are grown in close proximity to one another. To avoid surprises, grow only one genus and species variety at a time unless you can keep similar specimens completely separate. A plant’s Latin name will provide important clues about its likelihood of crossing with other plants in your collection.

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Choose seed plant specimens carefully – Small variations may make their way into future generations of even non-hybrid plants. If you’re collecting seeds instead of cloning plants, a little variability is inevitable. The trick is to hedge your bets by selecting plants for seed that represent your wish list for future generations. This can include things like hardiness, flavor, flower color, size and so on. Most experts agree it’s better to settle for fewer seeds overall than to harvest seeds from inferior plants. When you’ve made your plant selections, allow those specimens to dedicate their energies to setting seed. Once a plant goes into seed production mode, it has little energy left over for other types of activity, like producing additional leaves or flowers. Recognizing which plants you want for seed early in the growth process is one key to a good seed harvest.

Don’t harvest seed too soon – When it comes to harvesting seeds, timing is important. As gardeners, we’re used to harvesting plant products when they’re flavorful or at their most attractive. Flowers, fruits and vegetables typically produce mature seeds late in the growth process, though, usually after the flowers have withered, the pods have dried completely or the fruits have become overripe. When in doubt, wait. An immature seed will never sprout, so give seed stock plenty of time to mature.

Is that a seed, a bit of fluff or a twig? – It would be nice if all plant seeds looked more or less identical, but it doesn’t work that way. Seeds can look like dried petals, twigs, fluff, dead worms or other unremarkable things, or they can be so small they are difficult to see. Before you grab your harvesting kit, familiarize yourself with the appearance of the seeds you’re after so you won’t be disappointed later.

Dry seed processing – Although there are many plant varieties, most seeds are harvested using either a dry or wet processing method. Dry processing is about what you’d expect: allow seed heads to dry completely, preferably on the plant. Transfer seeds to a screen or other surface where they can be separated from extraneous plant material. If seeds can’t be dried completely on the plant, they can be transferred to a paper bag, or flowering heads can be suspended by their stems in a warm, dark location for additional drying.

Wet seed processing – Wet seed processing is used to prepare seeds from fleshy fruits like melons. Some quasi vegetables are handled in this way as well, including cucumbers and tomatoes. Fermentation is part of the process, which means the seeds aren’t dried on the plant. Instead, they’re removed from the fruit along with some of the pulp and allowed to mellow through the actions of naturally occurring yeasts. This typically takes a few days. Here’s how it works: A slurry of seeds, pulp and water is allowed to ferment in a cup, bucket or other wide-mouth container that is shaken or stirred regularly. Viable seeds eventually sink to the bottom of the container, while the pulp and non-viable seeds float to the top where they can be skimmed off. After five days or so, the seeds are removed and dried on a screen or paper plate, in a mesh bag or on another neutral surface. Different seed experts have their own methods for processing wet seeds, but they typically follow this similar pattern.

Seed cleaning – After drying, be sure to remove any debris from seeds before storing them. The presence of extra stuff can encourage mold or bacterial growth. Some veteran seed collectors recommend freezing prepped seeds for up to three days to kill any incipient bacteria or mold they may be harboring. A clean seed is a safe seed. Removing good seed stock from the surrounding chaff can be tiresome, but threshing and winnowing are both time-honored methods for removing large and small bits of debris from seeds. For the casual gardener, placing dried seeds on an old window screen and gently shaking the screen can help separate stem pieces, bits of leaves and partial seed casings. Employing a small, hand-held fan can also help.

Controlling temperature and humidity – The two most important factors when storing seeds are temperature and humidity. The temperature part of the equation can be pretty simple. Keep seeds in a refrigerator if you can. Other good choices are in a dry basement or root cellar. The humidity part can be tricky. For the pros, the optimal humidity for seed storage may be less than 8%. For the home grower using conventional drying methods, it probably hovers around 25% or so.

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Low humidity is achieved by choosing seed containers that seal well, paired with desiccants like silica gel that absorb ambient moisture. Seed savers have been using do-it-yourself moisture absorbers for a long time, including powdered milk, dried rice and non-clumping kitty litter. Just keep a layer of cotton or paper towel between the desiccant and the seeds.

Purists often prefer air-tight glass or plastic containers for seed storage. Where space is a problem, some green thumbs like using small envelopes stored inside larger sealable bags. Some popular options include coin envelopes, small parts envelopes, styrene or glass vials with snap-on caps (available for purchase in bulk), sterilized baby food jars and used (and thoroughly cleaned) prescription bottles.

Labeling – Keeping track of seeds can be a nightmare if you don’t maintain good records. Starting a gardening log is a good idea, but even if you aren’t into taking notes, be sure to label your seed stores carefully. The experts recommend including the plant’s Latin and common names, the date the seeds were collected and any special information you may think you’ll need later. This can include the source of the original plant or starter seeds you used, and what you want to achieve with your next crop.

Preserving seeds successfully requires some trial and error, but the process can be fun and rewarding. Growing your own seed is a nice way to re-create a gardening success, share your carefully cultivated good fortune with others or just save money the next time around. So, save your seeds. It’s the smart thing to do!

How to Properly Store and Preserve Cannabis Seeds [Explained]

If you don’t begin with great seeds, you can forget about producing a harvest of high-quality marijuana. A lot of growers seem to forget one simple fact: Your seeds are alive! Although cannabis seeds are fairly durable, improper storage can ruin them. If you’re paying $10-$20 a seed, losing a full batch is an expensive mistake.

Before your marijuana seeds germinate, they are in a similar state to animals when they hibernate. Like all living organisms, your seeds can die if you don’t take care of them correctly. The good news is that cannabis seeds can last for five years after harvest with proper storage.

In this guide, we outline how to store and preserve your cannabis seeds. We focus on the following:

  • Light
  • Temperature
  • Humidity
  • Storage
  • Insects & Pests
  • Germinating old seeds

Keeping Light Away from Your Marijuana Seeds

You must keep your seeds in a location that is cool, dark, and dry. It is best if you keep the seeds in their original packaging. When they are exposed to temperature changes or light, cannabis seeds begin using their store of nutrients. This is a disaster because they ultimately won’t have the nutrients to germinate.

When they are exposed to temperature changes or light, cannabis seeds begin using their store of nutrients.

Make sure your seeds remain away from light, as it can directly trigger germination.

What’s the Right Storage Temperature?

The best temperature to store your cannabis seeds at is between 43- and 47-degrees Fahrenheit. The lower the temperature, the less likely your seed is to germinate unexpectedly. Experienced growers tend to have special refrigerators to store their seeds. Ideally, your fridge is a no-frost model. If you can place the seeds in the fruit and vegetable section, that is even better.

Another option is to freeze the cannabis seeds. If you go down this route, please ensure that you vacuum pack them first. Then put them in a dark container. Also, it would help if you germinated these seeds immediately once they come out of the freezer. Don’t allow them to thaw first.

What About Humidity?

Here is a quick overview of what will likely happen to cannabis seeds at different humidity levels:

Your cannabis seeds need a certain level of moisture for germination. If the humidity level gets too high, your seeds will rot in storage. An extremely low level of humidity of around 8-10% is suitable only for long-term storage. If it drops below 8%, you offer any insects present in the seeds the chance to become active and start reproducing.

The Right Storage Options for Your Cannabis Seeds

You now understand that you must store the seeds away from direct light. We have also outlined the need for relatively low humidity and a refrigerator-level temperature. Different options are available depending on how long you intend to store the seeds.

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If you only require short-term storage, a dark drawer or cupboard is sufficient. The most important thing, regardless of the duration of storage, is to avoid temperature and humidity fluctuations. Rapid variations in temperature, in particular, can destroy your seeds. If you live in a location with warm daytime temperatures and cold nights, avoid outside storage.

For short-term storage, place the seeds in a container with desiccant. Seal it, and place it in a cool, dark place.


Once you enter medium-term storage (a few months), it is time to use an airtight container. Examples include a mason jar or Ziploc bag. Place this sealed container in the fridge. Remember that opening your fridge can cause significant temperature fluctuations. As a result, it is ideal if you have a second fridge that is seldom used.

Also, you should note that modern fridges have low humidity levels. If the humidity is too low, your seeds will begin using up nutrients.


If you want to store your seeds for at least six months, use a vacuum-sealed container. You can achieve this effect by removing all the air from a Ziploc bag. There are also special vacuum-sealed containers available online. Put the sealed bag in a dark container and put it in the fridge.

You also have the option of placing the seeds in the freezer. Remember, though; you need to germinate them immediately upon removal.

A Note on Insects & Pests

Imagine paying $100+ for seeds, going to the trouble of storing them, only to find that insects ruin them. Unfortunately, all you need is one insect in a container to destroy all of your seeds. The first consideration is to avoid exposure to ultra-low humidity. However, for long-term storage, this is precisely what you are supposed to do!

One option is to spread diatomaceous earth (D.E) where you store them. This is a type of sand that has a fossilized algae base. Crucially, for our purposes, it serves as an excellent natural insecticide. Unfortunately, you shouldn’t use D.E if you plan to store your seeds in a fridge with other food.

Imagine paying $100+ for seeds, going to the trouble of storing them, only to find that insects ruin them.

It would help if you also stored your seeds as high above the ground as possible. This reduces the possibility of a pest like a rodent coming in and feasting on the seeds.

Insects and pests also thrive in dirty storage areas. As a result, you must ensure the storage area remains clean. Otherwise, you won’t just attract pests to your seeds; microbes will form and damage the seeds. Do you want to consume marijuana from contaminated seeds?


You can ‘test’ your seeds once you have removed them from storage. Place them in water. If they sink, they should be fine. However, if they float, it is more likely that they are bad seeds. You can still try to germinate, but there is a greater risk of producing poor-quality cannabis, or else the seeds fail to sprout. You can keep floaters in water for approximately 72 hours to see if they sprout a tail.

If you have old seeds not stored in ideal conditions, there are still a few ways to germinate them.

  • Remove the hard ridge with a sharp knife.
  • Soak the seeds in carbonated water with germination booster, fulvic acid, or hydrogen peroxide. Use room temperature water, and perform this pre-soak for at least 12 hours in a dark area.
  • Scratch the tough outer shell with sandpaper. Believe it or not, this process could help warmth and moisture get inside. This process is called ‘scarring’ and should happen before you soak the seeds.
  • Make a small cut into the shell as a last-ditch attempt to get it to sprout.

Final Thoughts on Storing and Preserving Cannabis Seeds

If you purchase marijuana seeds and intend to use them almost immediately, you should have no issues. Even so, it is probably best to keep them away from direct light. In the short-term, a dark cupboard is sufficient as long as the temperature and humidity are reasonable.

Once the goal is to store cannabis seeds for months rather than days or weeks, everything changes. You need an airtight container, which you should store in a fridge. Include a vacuum-sealed container if you plan to store the seeds for several months or longer.

When storing cannabis seeds, you must ensure they are not exposed to germination conditions. This means keeping them away from direct light. Also, store in 20-30% humidity (8-10% for long-term storage) and a cool temperature. Keep the environment clean to avoid pests, and consider the tips above for germinating old seeds.