How long do weed seed last unplanted

Can Old Vegetable and Flower Seeds Still Be Planted?

Amy Jeanroy is a master gardener and farm homesteader who has operated a greenhouse business since 1999. She served as the herbal gardening expert for The Spruce for eight years. Using her expertise in herbalism, she makes and sells herbal soaps, tinctures, salves, teas, and recipes at farmers’ markets in Maine. She has also authored three books on canning and fermenting foods.

The Spruce / Lacey Johnson

Seed packets you purchase often contain more seeds than you can plant in one season, and over time you may have many partial packets of seeds without knowing just how old they really are. You might rightly wonder if they will germinate (sprout) again if you plant them. Do seeds go bad with time, or can you plant them no matter how old they are?

The answer is, yes, seeds will eventually go bad and no longer germinate, but it can take quite a long time. There is a good chance that those old seed packets will have a high percentage of seeds that will germinate just fine. Most seeds, though not all, will keep for at least three years while maintaining a decent percentage of germination. And even a group of very old seeds may have 10 or 20 percent that still sprouts.

Proper Storage

Your old seeds will stand the best chance of germinating if they have been stored correctly. All seeds will store most effectively in cool and dry conditions, so you should be wary of any seeds that are stored in opposite conditions—warm and moist. When you examine seeds, discard the entire packet if they show signs of mold or another fungus.

Many commercial seed packets may have a “use by” date printed on them. Don’t take this date too seriously—the seed manufacturers use this date to ensure that customers experience a large percentage of germination, and many seeds may remain viable for many years after the date printed on the packet. But the printed date will give you a sense of how old the seed packet is. If you are only a year or two beyond this date, there’s a good chance most of the seeds will still germinate when planted. But if the seed pack is six years old or more, expect to have a much lower percentage of germination.

Going forward, proper storage procedure is to date the seed packet when you buy it, to ensure that you’ll know exactly how old it is when you reach for it in the future. If possible, store the seeds in a sealed plastic bag containing a desiccant packet (those small packets that often come in over-the-counter medicine products), which will keep the seeds dry. If you don’t have desiccant, packets of dry rice or powdered milk will also absorb air moisture. The sealed seeds can be stored in the refrigerator or another cool place, but don’t freeze them.

Average Shelf Life of Some Common Seeds

Here are some estimated shelf life figures from Oregon State Cooperative Extension, based on research. Be aware, though, that even in seed packets much older than this, some of the seeds may still sprout.

  • Bush and pole beans: two years
  • Beets: two years
  • Broccoli:
  • Brussels sprouts: three to five years : three to five years
  • Cauliflower: three to five years
  • Carrots: three years
  • Collard: three to five years : three to five years
  • Kohlrabi: three to five years
  • Corn: one year
  • Cucumbers: three years
  • Leeks, onions: two to three years
  • Lettuce: three years : three years
  • Oriental greens: three years
  • Parsley: two years
  • Parsnips: one year
  • Peas: two years : two years
  • Radishes: four years
  • Rutabagas: three years
  • Spinach: one season
  • Squashes: three to four years
  • Swiss chard: two years : three years
  • Turnips: four years
  • Annual flowers: one to three years
  • Perennial flowers: up to four years
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Is There a Way to Test Seeds for Viability?

Seeds gradually lose viability as they age, so a packet that begins with a 90 percent viability rating on the packet may, after three or four years, have a much lower viability rate. A simple seed viability test, done by placing a small group of seeds on a damp paper towel to see how many sprouts, can tell you roughly how many of the seeds in the packet will be viable when planted.

If you have a group of seeds you’re not sure about, you can still plant them, but space them with greater density than you would for fresh seeds. Even if only 30 or 40 percent of the seeds germinate, you can still have a successful planting.

Can I Save My Own Seeds From the Plants I Grow?

Saving and starting your own herb, vegetable, and flower seeds is a great way to garden for just pennies each year. Be aware, though, that seeds collected from hybrid plants may not “come true” from the seeds produced. You can still save the seeds, and those seeds will still sprout into seedlings, but it is likely that the mature plants will demonstrate different characteristics than the plants from which you took the seeds. This is because hybrid plants are created by cross-pollinating different parent varieties, and their seeds do not carry the full genetic information. This isn’t always a bad thing. You may actually find that tomatoes from saved seeds, for example, are tastier than the hybrids, although they may not look as perfect. Flowers seeds saved from hybrid plants may produce some unusual and interesting offspring.

If you save seeds from vegetables and fruit you grow yourself, store them in the same way that you save seed packets—in dry and cool conditions.

How long do cannabis seeds remain viable?

Marijuana seeds should be kept in a cool, dark place such as a basement or in your refrigerator. They should be in an air-tight container and must stay dry. Putting a cotton ball in with the seeds before storage can help suck up any extra moisture (this is why you often see little bits of cotton in seed breeder packs).

Heat and moisture ‘signal’ to cannabis seeds that it’s time to sprout, so as long as you keep the seeds in a dry, dark environment they can remain viable for years. I have heard cases of seeds sprouting after being in storage for 5 or even 10 years. However, you will notice that older seeds take longer to germinate than fresh seeds and a few of them may not sprout at all. As time goes on, fewer and fewer of the seeds will successfully germinate.

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.

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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.

Short-Term

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.

Medium-Term

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.

Long-Term

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.

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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?

Germination

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.