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Video germinate cannabis seeds rockwool

How to germinate cannabis seeds?

Want to know how to germinate cannabis seeds? Then you’ve come to the right place. In this guide you will find tips for germinating seeds.

What do we need for the seed to germinate well?

Humidity – First of all, we need to give the seeds the impulse to germinate. Depending on the method chosen, we expose the seeds to moisture. The roots do not tolerate light, so always protect the seeds from light of any intensity during germination.

Temperature – Keep the room temperature around 22 degrees. Cannabis sprouts do not tolerate temperature fluctuations, so a higher position in the living room is ideal ( in the dark, of course ) Cannabis seeds can germinate even in colder temperatures, but expect it to take some extra time and risk of rot, which is same for higher temperature. The rule is higher temperature = faster sprouting but at the cost of the risk of rot.

Relax – Once the germination process begins, leave the cannabis seeds where you left them and do nothing about them.

Be gentle – If you are going to check upon the seeds, or want to manipulate them somehow, pay attention and be gentle. While you manipulating with sprouted seed, be very careful. They are more fragile than you think and could break off easily.

Correctly placed in the medium – Plant the germinated seed with the root downwards. It will help the seed to grow faster. Do not try to repeat process If you did not place them correctly, they will be just a little slower.

Correct depth – 0,5-1,5cm is the right depth. Use a thin stick to make a hole, then place sprouted seeds and close the hole so the light can´t endanger roots of your seeds

These are the factors that will positively influence germination itself. So what germination methods do we know?

Method 1: Place seeds directly to a medium

Rooting sponge

This sponge simulate the soil itself, so the seed will feel good. Working with these sponges is very simple. Carefully place the seed inside this sponge and then water it regularly.

Each of these sponges has a hole in its central part directly onto the future seedling, so you have a rather easy work.

Rockwool cube

Rockwool cubes are made of basalt wool and calcium in a furnace at high temperature.

Rockwool is the ideal medium for growing hydroponics. However, it can be used for germination. Rockwool does not have an ideal PH, so it needs to be placed in PH-adjusted water for 24 hours before use.

Peat planting tablets Jiffy

These small peat tablets are also very well known. The material is of plant origin (spahagna peat) and thanks to soaking in water it swells into a nice cylinder, into which you then insert the cannabis seed. The tablets are very airy, so the seeds will be like in heaven and take root faster. They contain minerals to adjust the acidity of the soil medium.

Method 2: Dip cannabis seeds in water overnight

A very effective method that is well built especially for older seeds.

Most of the quality seeds start swimming on the surface of the water, but eventually they sink to the bottom of the glass as soon as they are soaked with water. After a while, you’ll notice that the box is beginning to expand and a tiny root is sprouting.

The ideal soaking time is 24-32 hours. Some seeds have a harder cover than the other, so they don’t have to germinate in one single moment. But it should not take more than three days.

Ideally, allow 24 hours to pass and then remove the seeds and place them in a medium.

Method 3: Paper towel

Perhaps the classiest method of germinating cannabis seeds. Take a paper towel, soak it and wrap the seed in.

Expensive paper towels are not required. An alternative to napkins is a standard make-up swab or cotton wool but not with a chemical content. When you check the seeds, be careful if the budding root has grown through the paper/cotton wall.

There is a risk that the paper napkin may dry out. It is recommended to place it between two plates or cover it with an inverted bowl. Drought would probably kill the seed.

Check the sprouting seed every 12 hours. You can plant the germinated seed immediately.

How to plant sprouted cannabis seeds?

Once germinated, the seed is ready to be planted in the soil. If you have more seeds, it is good to plant them together.

The germinated cannabis seed is very fragile at this stage, so be super gently. If you happen to break or pluck a small white root by mistake, the plant may survive, but it will be severely paralyzed.

We put the germinated seed in the soil to the mentioned depth. A seedling can sprout in a matter of hours or days. If it takes more than 10 days, the seed probably didn’t make it. It can happen sometimes even to healthy seeds, it is a nature.

The first weeks of your seedlings

The soil must not contain large amount of nutrients at first. It will suffice to be well aerated. As the number of leaves increases, you can add a smaller amount of nourishment or plant it in your own super soil mix, which will contain the optimum amount of nutrients.

If you grow in coconut fibres or grow straight hydro, use 1/4 of the recommended amount of nutrition first. Once more leaves have sprouted, you can add 2/4. After a few days or add 3/4 and then after another few days add fertilizers by the guide.

Keep your pH under control. Whether it is a seedling or an adult plant, pH will always play an important role.

With seedlings, it’s good to start with something weaker or place HPS higher, if you plant the seedlings indoors.

Using the germination station

We’re talking here about a device that was created directly to germinate cannabis seeds, and that’s a germinating station. It is a mini greenhouse what keeps humidity and temperature inside. They are particularly popular in the USA and Holland. You can insert either root sponges or pellets into individual holes.

Video germinate cannabis seeds rockwool

If you’re ready to start growing and want to find out the best seedbanks that ship to the U.S. click here.

After acquiring growing equipment and cannabis seeds I now had everything I needed to start growing marijuana. The first major step in this process is germinating the seeds or getting the plant to sprout from the seed.

The Plan: Use Rockwool to Sprout and Grow

There are many numerous methods germinating seeds. Popular methods include using paper towels, solo cups or just directly inserting seeds into soil.

I decided to use rockwool cubes as my germination / sprouting medium. It seemed like many people had success using rockwool to start their homegrows. In addition, I liked how after they sprouted it’s easy to transport to soil (the cube has a solid structure) without disturbing the root structure which stresses the plant.

My plan for growing the marijuana plant using rockwool was as follows:

  • Insert the cannabis seed in the rockwool cube (1.5 inch size)
  • Let it germinate and sprout
  • Transfer the cube into a pot with soil
  • Let it grow and flower on my balcony
  • Harvest the fruits of my labor

When formulating this plan I was a little hesitant as I hadn’t seen that many people using this process. Most people if they use rockwool stay with rockwool in a hydroponic indoor growth setup. I didn’t find many people who took the rockwool cube and transferred it to soil after it sprouted and wasn’t sure if this would work.

From this Question & Answer post someone asked if you could use rockwool outside and answered:

Sure, you can grow autoflowering plants using rock wool cubes outside or inside. If you are using the large cubes you can put them into a fabric container, plastic, etc., but they do need a place for the water to run out of them when it rains and when you water.

Granted this was only one answer and didn’t mention if it’s OK to transfer rockwool directly into soil. A little further digging and I found this snippet from another guide which said:

Another method is to use 3″ rockwool cubes to start seedlings in, then put 20 of them in a litter pan, cover it with another pan, and transport this to the grow site. The cubes can be planted directly into soil.

That was good enough (I’m so trusting about stuff I read online) for me so I decided to proceed.

Below will show you what the whole process looks like in video form:

Preparing Rockwool Cubes for Germination

The downside to using rockwool is the need to prepare the cubes before you insert your seeds. Rockwool has a pH of 7.8 and plants like a pH range of 5.5 – 6.8. If you were to simply insert the seeds into rockwool soaked in regular water the pH would be too high and will cause the seed not to sprout or kill the seed.

To prevent this from happening you use an acid like pH Down (phosphoric acid) which can bring down the pH level of the water you plan to soak your cubes in. This is why it was important to buy a reliable pH meter.

Calibrating the pH Meter

The pH Meter I bought was new so even before I could start soaking my cubes I needed to calibrate it first.

Bringing Down the pH

Now I had to mix a proper pH water solution to soak the cubes in. I filled a plastic food container with Brita filtered water (don’t think this is needed, but why not?) and added 0.25ml (a few drops) of pH Down. I stopped when I got to a pH level of 6.1.

IMPORTANT NOTE: Use pH Down sparingly as it’s a strong acid and will quickly bring down the pH level if you use too much. I ended up going too low and had to add more water to bring the pH back up. Better to be more conservative with this stuff.

Soak the Rockwool Cubes

With the rockwool cubes properly pH adjusted to 6.1 I placed 5 rockwool cubes into the solution for 60 minutes. As for the exact time to soak I found conflicting advice. Some guides said to soak for a whole day while others said 15 minutes. I took a gamble with 60 minutes.

Remove Cubes and Let Drain

After 60 minutes I removed the rockwool cubes and let it drain in the sink for 10 minutes. I was surprised how little water came out and how firm the cubes still were after being soaked. I thought from pictures that rockwool would be like a sponge, but it holds its structure surprisingly well.

Another tip I learned is to not squeeze out or shake out the water from the cubes. You want the cube to be damp as the wetness is what helps trigger the germination process.

Saving Some of the pH Adjusted Water

Instead of tossing away the reduced pH water I saved some in a separate container. As you wait for your seeds to sprout you may need to re-water the rockwool cubes if they get dry. Re-using this water saves you from having to mix up another batch of reduced pH water.

Insert the Seeds and Store

Now that the cubes were properly prepared it was time to insert the marijuana seeds and store them in an ideal sprouting environment.

Inserting the Cannabis Seeds

I placed the cubes into the seedling starter tray and then inserted each seed about a quarter of an inch into the 1.5 inch cube. The seeds are really tiny so to help I used tweezers to place them inside the cubes.

Here’s a video of me inserting one seed into a cube:

Place Humidity Lid and Store

With the seeds now inserted I placed the humidity dome / lid onto my starter tray (came with the set I bought). The reason for the lid is it helps keep the humidity high which assists with the germination process.

In addition to humidity in order to trigger the sprouting process experts advice to place the seeds in a dark environment. This mimics being in soil and coaxes the seed to sprout. To do this I placed the tray onto a shelf in a storage closet.

Wait for Sprouting

Once setup it could take anywhere from a few days to a week or more before the seed sprouts. Just check on it each day to see the progress. You probably won’t need to add additional water as rockwool does a good job at retaining water. However, if you touch the cube and feels dry it doesn’t hurt to add some of the pH-adjusted water you saved from earlier.

Below you can see a time-lapse of a marijuana seed germination process.

FAQ on Cannabis Seed Germination

If you are using the rockwool cube germination method and have followed the procedure correctly it could take 2 days or up to a week for it to germinate. If it’s over a week there could be issues.

Don’t get too deep. No more than a quarter of an inch.

Find a dark place or room to store the seeds. In order to germinate the seed needs to be in darkness so avoid places where light could leak in.

You need to make sure the pH of the water you used is in the correct range, 5.5 – 6.8. Depending on your pH meter it could be off as well if not properly calibrated or if you are using a cheaper pH meter. In these cases try removing the seed and re-soaking the rockwool cube in another batch of pH-adjusted water

There are multiple ways to germinate seeds. The rockwool cube method describe here is just one method. In addition, another popular method is the “paper towel” method where you place the seeds into a water soaked paper towel.

Successful Germination, Now What?

Congrats! If you succeeded in getting your cannabis seeds to sprout you are now on your way to growing a healthy marijuana plant.

Checkout our other marijuana grow phases posts to make sure you continue to succeed.

How to Germinate Cannabis Seeds

This article was co-authored by Lauren Kurtz. Lauren Kurtz is a Naturalist and Horticultural Specialist. Lauren has worked for Aurora, Colorado managing the Water-Wise Garden at Aurora Municipal Center for the Water Conservation Department. She earned a BA in Environmental and Sustainability Studies from Western Michigan University in 2014.

There are 10 references cited in this article, which can be found at the bottom of the page.

This article has been viewed 61,459 times.

Cannabis sativa sp. is commonly known as marijuana and has been grown throughout the world for thousands of years. Cannabis seeds germinate in 3 to 7 days, though some varieties may take 10 to 15 days. While germination is a natural process, factors such as light, humidity/moisture, and temperature must be controlled for cannabis seeds to sprout.