Professional Marijuana Grower


Germinating Cannabis Seeds

Posted June 15th, 2017 by Robert Bergman in ,

Germinating cannabis seeds paves the way for healthy development of the plant, so it is very important to make sure that every need of the seed and germ are fulfilled. Like every plant, marijuana begins with a seed, which requires water to grow. The seed houses the entire plant and can survive the first few days with a reservoir of food. While it is germinating, the seed can turn this saved food into sugars, which it uses to grow.

We will uncover the process of germinating seeds as well as perfecting the conditions for young seedlings. Additionally, I will go through the different methods of germination, as well as the advantages and disadvantages of each method.

Cannabis Seeds

Like every plant, marijuana begins with a seed, which requires water to grow. The seed houses the entire plant and can survive the first few days with a reservoir of food. While it’s germinating, the seed can turn this saved food into sugars, which it uses to grow. A seed increases in size and breaks open when it has received enough moisture. A germ opening forms, allowing the root to go through, and it goes down into the ground.

Because its downward motion is due only to gravity and not some other force, the root will always grow downward–even if the seed is positioned in a different way. Consequently, the stem consistently grows opposite to the root, so it will always grow upward.

Germinating Cannabis Seeds

There are a variety of ways to germinate cannabis seeds and each has its pros and cons. Rockwool cubes, soil or peat pellets are all suitable for the germination process. As long as the amount of moisture and temperature are right, they should all achieve the same thing in the end. Let’s start out by going through my favorite method of germinating cannabis seeds: water germination coupled with soil germination.

I first submerge the cannabis seeds in water and let them soak for 24 hours. This assures that there is the right amount of moisture to begin germinating. The seeds won’t absorb too much water unless they’ve been soaking for 7 days or more, so don’t be concerned about that.

Pour tap water (no added nutrients needed) into a cup and let it sit for several hours, allowing it to get to a room temperature. Even if the seeds haven’t broken open, the seeds will have begun to germinate after 24 hours.

Germinating Seeds in Soil

Because soil makes a cushion of water and nutrients, it is very easy to germinate cannabis seeds in soil. Use mildly fertilized potting soil or a seed-starter; the pH level of proper soil should be approximately 6. Seeds are delicate and can negatively respond to an overdose of nutrients. Potting soil should contain the right amount of nutrients to work for two weeks or so, and it is available in most garden centers.

After putting soil in the pot, (one pot per seed), you can use a pen or pencil to make a quarter-inch-deep hole. If a root has already popped out of the seed, you can help it grow faster by making sure that part faces downwards. Once the seed is in the hole, make sure it is topped with soil; don’t push down the soil, however, since this will occur automatically when you water it.

The seed will germinate, and plant will pop out of the soil in a few days or a week. Below the soil, many new roots will grow from the main root and a solid system of roots will form.

Watering Seeds

Like all living things, water is the most important element in germinating seeds. For this reason, you need to be sure that you feed your plants the perfect amount of water. If you water it too little, the plant will try to conserve energy in order to survive, and won’t grow to be very large.

If you water it too much, the roots will not get enough oxygen, making the roots rot and the plant above to go limp. Wet soil can also attract mold and other harmful bacteria.

To make sure the plants receiving enough water, add water until you it begins seeping out from the bottom. Even though the seedling doesn’t absorb this much water, it evaporates very quickly. Consequently, this amount will just last for several days.

Light and Temperature

Light is the second most important ingredient to growing a healthy marijuana plant. Light gives plants the ability to form sugars from carbon dioxide and water. These sugars are used to power the plant’s growth. This is referred to as photosynthesis.

The amount of light is very important, as it affects the precise way in which plants grow. For instance, if plants receive too little light, they will only grow in height and not in width, and won’t produce many branches. This is due to natural selection in their natural habitat; if a plant can grow above the others, it has a competitive advantage because it will absorb more light.

Plants that already have access to enough light will also achieve growth in width. More branches and therefore buds will crop up, which is ideal for cannabis plants. Keeping light throughout the day (both day and night) helps accomplish a consistent temperature and maximizes plant growth.

Placing the seeds in containers under fluorescent lights is best, since the lights do not use too much power and don’t emit much heat, allowing you to place them quite near the plants. Although the seeds don’t actually need the light at this point, an immediate exposure to enough light once they pop out of the soil will help them develop best.

The temperature should remain near 73 degrees, but if it’s too hot then simply move the lamp further away from the plant. Wrap plastic wrap around the pot so all the extra moisture cannot escape, thus creating the perfect humid climate for the seeds to germinate.

The plants should appear after 3-7 days, as long as you are closely monitoring the temperature. Remove the pot’s “lid” (plastic wrap) as soon as you see the first sprouts; then have the lamp on at intervals of 18 hours on and 6 hours off.

Germinating Seeds in Rockwool

Rockwool is mineral wool that comes from volcanic rock and other materials (basalt and limestone, for example) and provides the perfect environment for the growth and germination of plants. The stones are formed by heating them up to 1500 degrees Celsius, turning them into molten lava, which is then quickly spun, releasing drops of lava that solidify to form threads.

These threads are further processed with compaction, curing and cutting, turning them into the Rockwool forms that we know (including slabs, blocks, and plugs.)

Seed Starting in Rockwool

The main difference in this process is the addition of fertilizer; Rockwool doesn’t contain the nutrients that soil has, so you’ll need to add a bit of fertilizer (TDS should be around 600 ppm) when you start seeds in Rockwool cubes. Additionally, the pH level is 7.0, which is too high for optimal germination, meaning you’ll need to lower the Rockwool pH.

This is achieved by placing the Rockwool plugs in water (pH value 5.5) for a full day, allowing it to bring down the Rockwool’s pH level. Although it can be a bit trickier, there are some pros to using Rockwool instead of soil. First, while transplanting, Rockwool cannot have a harmful effect on the roots (which can occur when using soil). Of course, pH and TDS meters are necessary for successful Rockwool germination.

Germinating Seeds in Peat Pellets

Peat pellets are simply compressed peat within a bag made from mesh; this peat enlarges when you add water and turns into a sort of container. With the pH level of 5.5 and the TDS at 625, peat pallets create the ideal environment for germinating cannabis seeds and growing plants.

You can also put the peat pellets straight into the soil or Rockwool when the roots start to appear, thus avoiding damage to the roots altogether.

Germinating Seeds in Water

If you allow marijuana seeds to remain in water for 24 hours, the seeds can be pre-sprouted. This allows viewing of the seeds, and it ensures that they have plenty of moisture for starting the germination process. Additionally, germinating cannabis seeds in water is a faster process than planting them directly into the soil.

This method isn’t perfect, however, as it means the seeds will need to be picked up (whether or not a root is already emerging). This root is extremely delicate and if it is harmed, it could be detrimental to the development of the plant, so you must be extremely cautious when touching a seed with an emerged root. To save time, plant the seed with its root facing down. Although others might disagree, I have found that this method is the best one and have continued using it for years.

Germinating Between Cotton Pads

Placing cannabis seeds between wet cotton pads is also a suitable method; like with placing the seed in water, this process ensures the seeds will have plenty of moisture. On the other hand (also like the water method), the seeds will need to be picked up and moved, thus risking harm to the root. If this is done cautiously, this should not present many problems.

The roots should be growing out of the seeds and visible in 2 to 5 days’ time and should be moved at this time. Do this by removing the cotton pads with caution and placing them into the soil or Rockwool, either with your fingers or tweezers.

Germinating Seeds Outdoors

I do not recommend germinating cannabis seeds outdoors. It is easier to maintain the suitable temperature inside, as well as the level of water and light. This applies even if you will actually grow the plants outdoors. Outdoors there can be variants in rain, clouds and other things that can negatively affect the germination of your seeds. Germinating inside also allows you to end up with bigger plants and a greater yield since you can start the growth earlier.

Germinating seeds outdoors means waiting until the final frost has passed before starting. You can easily grow your plants outdoors by germinating inside and then moving the plants outdoors once they are bigger and stronger. The healthy start helps these plants endure much more than young seedlings that are germinated outdoors from the beginning.

If germinating inside is simply not possible or not worth the inconvenience, you can begin germination in the location that you plan to fully grow the plants. This provides a certain advantage; since you are not moving the seeds, you’re also not risking accidental destruction of the root.

Before planting, dig holes (6 x 6x 6 inches) in the ground and fill them with potting soil. This will provide the seeds with enough nutrients for the beginning. After that, create a small quarter-inch-deep hole and plant the seed inside. Make sure that you soak the soil in water. You might even want to add some more water in a few days if the weather is particularly warm. Make sure to plant the seeds 3 feet apart. Under the right circumstances outdoor marijuana plants can get very large and you do not want them competing with each other.

Speeding up the Process

You can speed up germination and kill infectious agents by soaking the seed for 12 hours in a 1% hydrogen peroxide or compost tea solution. Position the seeds in sterile planting mix, planting pellets, Rockwool or pasteurized soil at about a quarter of an inch deep. Then, water the seeds with a 0.5% hydrogen peroxide solution with an added bloom fertilizer at about 25% strength.

Try to keep the medium consistently moist by covering the whole apparatus with a dome to ensure constant humidity. It is best to keep the medium out of the sun and at a temperature of 72*F. Depending on the age of the seed, they should germinate between 2 and 10 days (older seeds take longer than younger ones). Keep a firm light on the seedlings or else they will become leggy.

For outdoor plants, the seeds should be planted during the season in which corn is planted in your area. You can hasten the season with row covers, but this can cause vegetative growth and flowering problems if there is a critical dark period involved. This happens occasionally when the plants are put outdoors early in the season.

The seeds need to be planted about a quarter of an inch deep on tilled soil or simply drilled into untilled soil.

They need protection from weeds and overgrowth, but when they reach unobstructed sunlight, they will soon take over the entire canopy. Many strategies for germinating cannabis seeds are available; you simply have to choose which one is easiest for properly maintaining the needed moisture and temperature level.

Background information for this story was provided by Robert Bergman from

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