4 Top Ways How to Germinate Old Cannabis Seeds so they Crack Open

You may have found some old cannabis seeds that you forgot about.

Or maybe haven’t gotten around to planting them and are wondering how to get them to germinate.

The older they are, it’s hard for them to crack their shell.

I have tried various ways to get older seeds to sprout, some successful some not.

There are methods that work better than others.

These are the methods we found to help germinate old cannabis seeds and get them to sprout.

 Let’s check them out,

How to germinate old cannabis seeds:

Pre-soak method

The pre-soak method is one way to kick start and germinate old cannabis seeds into sprouting.

We usually start all of our seeds off this way even if they are newer seeds.

It’s recommend you have your water solution at room temperature around 20 degrees Celsius or 68 degrees Fahrenheit.

You can have it warmer depending on the climate you live in. But not too hot.

** Please note: Do not soak your seeds longer than 20 hours or you risk drowning them **

There are a few different additives you can use hydrogen peroxide, carbonated water.

We have also heard of fulvic acid but (it is not covered in post because we never used it.)

germinate old cannabis seeds

Hydrogen Peroxide:

When using Hydrogen Peroxide in soaking your seeds it adds extra oxygen to the water.

This can help the cannabis seeds absorb the extra oxygen for the tap root. Roots like oxygen.

To make this solution use a ratio of 100:1. Use 100 ml of water to 1 ml of hydrogen peroxide.

Next take purified water at room temperature and mix in your hydrogen peroxide.

Then place water solution in a shot glass or glass of your choice then drop the seed in.

Put the glass in a dark warm area.

Wait anywhere from 8-18 hours, tap the seed to see if it sinks. If it does then it has absorbed the water it needs.

You can now either plant it in the medium, pointy side facing down.

Or you can place then in a paper towel soaked container with your hydrogen peroxide solution and use the paper towel method to sprout them.

Carbonated water:

To use carbonated water to germinate old cannabis seeds it’s really simple.

Use room temperature carbonated water (un-flavored).

We recommend you have your water solution at room temperature around 20 degrees Celsius or 68 degrees Fahrenheit.

You can have it warmer depending on the climate you live in.

Simply drop your old cannabis seed into the water and store in a dark warm area for about

Put the glass in a dark warm area.

Wait anywhere from 8-18 hours, tap the seed to see if it sinks. If it does then it has absorbed the water it needs.

You can now either plant it in the medium, pointy side facing down.

Or you can place then in a paper towel soaked container with your hydrogen peroxide solution and use the paper towel method to sprout them.

Scratch Method:

With the scratch method it’s really simple to do all you need is a fine grit sand paper. 

Some people use an empty match box to put the sand paper in.

Then the next step is to simply put the seed in a “matchbox with sand paper” and give it a shake once or twice is enough.

What I have found best if you don’t have an empty match box and do not want to take all the matches out of the box.

Cut a piece of sand paper about 3 inches by 3 inches.

Next roll it up so it’s the shape of a tube and wider than the seeds,  then put some tape on it to keep it together.

Then just put your finger on one side of the opening to close it.

After that place the seed in the tube of sand paper put your other finger on top and give it a shake once or twice is all that is needed.

Once your old cannabis seeds got there shake on.

The next step is to put them either in a Pre-soak, paper towel method, or grow medium of your choice soil coco, rockwool.

Slice Method:

 The slice method is the last resort and a very extreme measure to try and get the seed to germinate and sprout.

After you have tried the methods mentioned above.

You will need a very sharp knife like a razor blade (make sure it is sterile, use some alcohol on it)

Take your old seed and make a slice along the middle of the seed where you can see the division of both sides of the seed.

Now place the seed into the soil, coco, rooting plug or Rockwool of your choice.

Ridge Method:

Some cannabis seeds have a ridge on one side of the seed that is protruding.

You can try and gently remove the ridge with a razor blade if you wish this may allow the seed to sprout open.

Then place the seed into a growing medium or a sprouting method like paper towel or rooting plug.

cannabis plant

Final Thoughts

Trying to germinate old cannabis seeds can be very difficult.

Especially if they are not wanting to crack open. About 50 to seventy 75 percent of the time this can be the case.

Try to use some of the methods mentioned like the scratch, pre-soak, and paper towel method.

You could be on the right track to getting them to sprout out.

When you have old seeds you should always try and germinate them.

Because you never know they just might grow up to be a fantastic cannabis plant.

If you want to learn more about germinating cannabis seeds check out our post on it here: Germinating marijuana seeds

Let me know in the comments your methods or if you had any success?

Keep growing!

p.s. if You need any seeds check out the deals at Seedsman.

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