Guide to Germinating Seedlings

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Whether you’re planning on starting a cannabis farm or wanting to start a few plants for medical reasons, growing your own plants begins with germination. Additionally, seed germination is a determining factor in the success or failure of plant growth.

In fact, proper germination will allow the seeds to sprout into healthy seedlings.

Note: For general purposes (GPs), a seedling is a young developing plant that has started from seed.

Guide to Germinating Seedlings

Cannabis seeds can sometimes be difficult to sprout. In addition, if the sprouting seeds are in a poor environment, your seedlings can be lanky and tall.

Unfortunately, the stems of lanky seedlings often break and cause the plant to die. As well, you will not get a harvest if your plants fail to germinate entirely.

Fortunately, there are a few techniques that can help cannabis seeds germinate successfully. In fact, knowing a few proper methods will drastically help with a dynamic germination.

What are the Best Ways to Germinate Seeds?

Germinating cannabis seed is relatively pretty easy. However, there are few things to consider if you want a high germination rate. To begin with, you need viable and healthy seeds.

If you plant seeds that are not healthy, the chances of producing unhealthy plants are pretty high.

Guide to Germinating Seedlings

The best quality seeds are dark brown in color and feel solid. Do not try to germinate white or pale green seeds. These seeds are immature and most likely will not sprout.

Basically, seeds require three factors to germinate

  • Oxygen
  • A high moisture level (80-100%)
  • Consistent temperatures: 68-75°F (20-24ºC)

Before planting your cannabis seed, you should soak them in purified or filtered water for a maximum of 32 hours. This helps hydrate the seed.

Never soak your seeds longer than 2-3 days. Seeds that are immersed in water to long will rot.

Note: Reverse osmosis (RO) water is also good to use for soaking your seeds.

Marijuana plant on a black isolated background, large buds, cannabis industry, seeds and clones

Once your seeds have been soaked, you then need to place them in a medium that is perfect for germination. There are various materials that can be used for sprouting you seeds:

Paper Towel – One of the most popular methods of germinating. Simply place your seeds between two moist paper towels.

Avoid using too much water, the paper towels should be humid not saturated. Place the moistened paper towels on a tray or dish and leave it in a dark and well-ventilated area that has a stable warm temperature.

Cannabis hemp and seeds on a table

Keep the paper towels moist by lightly spraying with filtered water. Never allow the paper towels to dry out. Check them about two times a day.

Peat Moss or Coconut Coir Fiber Pellets – These pellets are perfect for retaining the right amount of moisture and oxygen. Make sure to hydrate the pellets before using.

Once they are moistened, place the seeds in the pellets. Like the paper towels method, you want to make sure the pellets stay moist but not saturated.

Canadian sphagnum peat moss

Rooting Cubes – These cubes are constructed with composted organic matter and have a texture similar to foam. The have excellent water and air ratios and are ideal for germinating seeds.

Rockwool Cubes – These cubes are a popular item for commercial hydroponics growers. They are also known as stone wool and mineral wool.

They are composed of long strands of natural fiber with chalk and basalt rock. The cubes are renowned for retaining moisture as well as oxygen.

How Deep Should the Seeds be Planted?

Regardless of what type of medium you choose for planting, your seeds need to be planted about 2-3 millimeters deep or 3/8 to ½ inches below the surface line. In addition, the white root needs to be facing downwards so the tap root is not overexerted.

If you plant your seeds to deep, they will struggle to reach the soils surface and it will weaken their growth. If the seeds are planted to shallow, there may not be enough soil moisture for the seeds to uniformly germinate.

What are Some Things you Can do to Increase the Chances that your Seeds will Sprout?

For germination to take place, the seeds need to stay a consistent temperature between 73-77°F (22 – 25° C). However, some experts say the temperatures can be up to 82°F (28°C) and be as low as 71°F (22°C).

Keep in mind that lower temperatures will result in slower and less successful germination. With too high a temperature, seeds are more apt to grow fungi and rot. In addition, the relative humidity should be around 70%.

To maintain an even and constant temperature, it is oftentimes necessary to use thermal cables or a heated greenhouse. In truth, greenhouses are perfect because they provide the ideal humidity for germination.

Marijuana seeding

After the seeds start sprouting and poking through the growth medium, you may want to consider using grow lights. According to 101 Grow Lights, the best lights to use for seedlings are CFL grow lights.

For positioning, make sure that the grow light is at least 5 inches (15 cm) away from the seedlings. It is also recommended that you place your hand between the seedlings and light to test the temperature.

If the grow light is to close, it will literally burn the plants. If the light is too far away, the seedlings growth will be stunted.

How Long Will it Take the Seeds to Sprout & Germinate After they are Planted?

Depending on conditions, cannabis seeds take about 2-7 days to germinate. Your seeds will start to crack open and begin to sprout.

The vegetative stage is about 3 to 8 weeks or more. At this stage, the seedlings are growing only stems and leaves.

Close view of hemp seeds, macro photo

In around 2-7 days, the seeds will begin to crack open and tap roots will begin to sprout up. Let them grow to around ¾ of an inch before planting.

When it is time to plant the popped up seeds, use a pair of tweezers to gently remove the seeds that may be stuck in the paper towel. Do not pull out to avoid damage on the newly sprouted seeds.

Should Seeds Get any Light While They are Germinating?

Seeds should always stay in a warm, humid, and dark environment until they sprout. In fact, if the seeds are exposed to light while they are sprouting, it can slow or completely stop the germinating process.

How Long Should You Wait before Transferring Seedlings to Soil?

There are various signs that determine when to transplant your seedlings. Transplanting too soon can stunt the growth and sometimes fill the plant.

Waiting too long to transplant can force the stem to grow too long and lanky, making it susceptible to breakage. Knowing when to transplant can make a huge difference in your plants health.

Here are a few signs to look for:

Dry soil – If your plants need constant watering, they probably need transplanted. A very thirsty plant usually indicates that it is root bound and need more room to grow and flourish.

Leaves are turning yellow – Another possible root bound issue is when leaves start to turn yellow. Signs of yellow leaves mean that the plant is in too small of a container.

Marijuana Plant

Droopy leaves – Your plant may be root bound if the leaves start drooping. This is because the plant is not getting enough nutrients and need more room to grow.

The plant is falling over – When a plant falls down often, it generally means that it is too big for the pot it is in. Oftentimes, a plant needs to be staked so that it stays upright. It is definitely time for transplanting when a plant cannot stand up by itself.


There are various reason why your seeds may fail to germinate such as bad or immature seed, not enough water, allowed to get to hot or cold, and the medium was kept to wet.

However, if you follow the basic guidelines for germinating seeds, you should have a very successful germination rate.