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Care and Caution When Germinating Cannabis Seeds

By Rich Hamilton | Last updated: June 7, 2021
Key Takeaways

For growers looking to produce top-shelf cannabis, it all starts with the seeds. Rich Hamilton explains there’s far more involved than simply burying a seed in a pot of dirt.

There are many to consider when germinating cannabis seeds — not only the germination method you choose but also the environmental conditions your seeds require to thrive. These conditions include temperature, light exposure, moisture, and oxygen levels. Get any of these wrong and it could spell the end for your grow before it even begins.

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Cannabis seeds can be very delicate and temperamental even when germinating in the perfect conditions. You can understand why you should approach this task with best-practice knowledge and caution.

To try and give your seeds the best chance, we are going to look at some tips and methods to help you get better results, first time, from your germination efforts.

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Firstly, what is germination? Well, germinate means “to bring to life.” Germination is the first part of a plant’s life, the growth or shooting of a seed into a seedling and then hopefully a plant.

Cannabis seeds germinate via epigeal germination which sees the cotyledons (seed leaves) pushed upward and out of the soil as the plant begins to grow. For germination to occur, several natural elements and conditions must be present in the correct ratios. Let’s have a look at them.

Water — This is needed to start the germination process as the seed is dry, holding only five percent water and needs to absorb a lot more to begin the germination process. Seeds store starch, oils, and proteins and when germination begins, hydrolytic enzymes are activated, releasing the stored supplies and giving the plant just enough of the right chemicals to get it started. Water is also needed to expand the seed’s shell and soften it, allowing it to split for the beginnings of the plant to emerge. The hardness of a cannabis seed shell can vary quite a lot. If your seed is ripe and mature enough for germination, then you shouldn’t have any problems. A more immature cannabis seed, however, will have a more rigid shell and may fail to germinate.

Oxygen — Seeds need to breathe, but without oxygen the seed may drown or suffocate. Overwatering can suffocate your cannabis seeds preventing oxygen from getting to them, so keep them moist but not soaked. Don’t overwater your seeds — use a spray mist rather than pouring water directly onto them.

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(Read also: From Seed to Harvest: The Life Cycle of Cannabis)

Temperature — Ideally, your cannabis seeds will germinate best at their “sweet spot” between 70-75°F. If you germinate a cannabis seed outside this range, then it can negatively affect the plant’s growth and health in the future. When temperatures are too cold, it can ultimately stunt germination so keep seeds away from any drafts, open windows, or fans.

Light conditions — Cannabis seeds germinate best in dark conditions. During germination, your cannabis seed is working to develop its first root (the radicle), and roots (unsurprisingly as they exist underground) do not like light! It is therefore vital to keep your cannabis seeds somewhere dark until transplant. But as soon as germination occurs and your new seedling develops leaves, it will need to be exposed to light to start the vital task of photosynthesis. Now that we understand what your cannabis seeds need, let’s explore the most popular methods used to germinate them.


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Cannabis seeds germinating in a glass of water

The Glass of Water Germination Method

You can leave your cannabis seeds in a glass of mineral water in a dark environment until the radicle/tip of the root shows.

Depending on the seed strain, you should generally see something happening within one to five days. Why mineral water? Well, depending on where you live, your tap water can vary immensely in terms of chemical composition and pH. The ideal pH for water when germinating is pH 7. Anything outside of this can have adverse effects on your seed. Using mineral water is a cheap and effective way of keeping a stable pH environment. If you use tap water, however, leave it to stand for 24 hours first. The tap water needs a chance to settle and dissolve any chemicals that are present and may be harmful to the seeds.

You can use an air stone and pump to oxygenate the water whilst it stands for 24 hours. By doing so, you will reduce the chance of the seeds drowning and helping to dissolve any unwanted chemicals at a faster rate.


Germinating cannabis seeds in a paper towel

The Paper Towel Germination Method

Using a paper towel to germinate your cannabis seeds is both reliable and straightforward. You should find that 90 percent or more of your cannabis seeds will germinate when following this method correctly.

Take a sheet of premium paper towel and fold it in half, then place the seeds to the left of center. If you are germinating more than one seed, then you can use the same piece of kitchen towel but do not let the cannabis seeds touch each other. Now fold the kitchen towel in half again so all the seeds are covered up and then saturate it with water.

Mineral water is excellent to use, or if you are going to use tap water, then follow the recommended process for the glass of water method as previously discussed. Now leave the kitchen towel on a plate in a dark place as the roots will hopefully begin to develop soon and they do not like the light.

(Read also: Grow a Fat Stash Fast: A Minimalist Approach to a Quick Cannabis Grow)

Humidity levels are equally important and keeping the seeds in the paper towel will keep the humidity levels where they should be. Keep the kitchen towel moist at all times and do not let it dry out. If you have been successful, it should take about two to four days for you to see until the radicle begins to emerge.

It is best practice to place the moist kitchen towels between two clean plates. Doing so helps to stabilize temperature and humidity and block out any light. The plates should be face-to-face, with the germination towel in between. Once a cannabis seed starts showing signs of successfully germinating, you can easily remove them whilst leaving the others, which may not yet have germinated, undisturbed.

Cannabis seeds on top of soil

Direct Germination Method

Germinating “directly” is where you place the cannabis seed directly within a pellet or block of a medium of your choosing. You can germinate your seed within a soil or coco pellet, however, I would recommend choosing a one-inch rooting sponge or stonewool cube.

You can use a soil pellet, but the risk here is that soil already contains a certain level of minerals and elements that could cause an imbalance in your seed, affecting its development later on in life.

For seeds in their natural environment, there can be double, triple, or a hundred times more plants growing in the soil at any one time. From those plants, thousands of seeds are dropped for germination and of those thousands, only half may germinate, even under natural conditions.

We are trying to grow our seeds under controlled conditions and in much smaller numbers. The margin for error, therefore, is much smaller. Using a rooting sponge is an excellent alternative for germination as it eliminates any risk of deficiencies or toxicities you may otherwise experience when using a natural medium such as soil at this early stage.

The direct method of germination can be hard to control as you must wait until the seedling first shows itself out of the chosen medium to know whether it has been successful or not.

As the cannabis seed is buried within its medium, you cannot check on it during the process to see if it has begun the germination process. As a result, this process can take much longer than the methods already discussed.

(Read also: How to Transplant and Harden Off Cannabis Plants for Outdoor Growing)

If you are germinating “directly” then firstly you should moisten your medium by misting it with a spray bottle. The cannabis seed will then need to be carefully inserted into the chosen medium and be surrounded by its encasing environment to keep any light out.

Now that you have chosen your method and you have successfully germinated some seeds. What now? How do you know when you should transplant? If everything goes according to plan with your germination efforts, you will see the radicle/root tip of the cannabis seed breaking through the shell. This new root is the first sign germination has occurred. It is best to transplant each seedling when the radicle is around three times the length of the seed.

A rooting sponge is a perfect choice for transplanting as it is compatible with whatever medium or system you use later. Rooting sponges are also an excellent choice for those who are looking to sell their seedlings.

Rooting sponges and stone wool blocks make for more robust root systems. It can take longer for the roots to break through, but when they do, they will be stronger.

When you are transplanting the seed, it must be placed radicle first into its new home, quickly, gently, and precisely as it only has a minimal amount of energy to survive and develop into a seedling. Once your seeds are transplanted, they should go into a propagator, ready for the start of the growth phase of their lives. Your cannabis seed holds all the potential to give you the vibrant, robust, healthy plants, and bountiful yields you desire.

Taking the time and care to get your seeds off to a good start should be a no-brainer. Knowledge is power if you want to be a better grower, so think of the learning process just like a seed itself. Nurture it, cultivate it, and you will soon harvest success.

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Written by Rich Hamilton | Writer, Consultant, Author of The Growers Guide

Profile Picture of Rich Hamilton

Rich Hamilton has been in the hydroponics industry for more than 20 years, working originally as a general manager in a hydroponics retail outlet before becoming an account manager at Century Growsystems. He enjoys working on a daily basis with shop owners, manufacturers, distributors, and end users to develop premium products.

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