Cannabis Growing 101: How to Germinate Weed Seeds

If you're interested in cultivating your own cannabis plants, then seed germination is the first step (after gathering all the growing essentials).

This article explains what to look for when planning to germinate a cannabis seed, the different germination methods, and how long the process takes.

What is Germination?

As is the case for most plants, cannabis begins its life as a humble seed. But before it can grow into a flowering bush full of the THC and CBD we're all after, those seeds must germinate. 

Germination is the process in which a seed sprouts out of its protective shell and grows into a seedling. 

Cannabis seeds won't just germinate automatically. The conditions and environmental cues must be right for the process to occur.  That means many cannabis cultivators – both professional and home growers – begin their growing process by germinating or "popping" marijuana seeds. 

Generally speaking, when a seed is placed in a moist environment, it will absorb some of that water (along with oxygen), and the embryo within will start to grow. Eventually, the embryonic root of the seedling, called the radicle, will break out of the seed’s protective shell, followed shortly after by the plant's stem, or plumule.

While the biological process is straightforward enough, a lot more goes into successfully germinating cannabis seeds. 

First and foremost, you'll need to ensure that you start with high-quality seeds so they can grow into high-quality plants. You also need to know when your cannabis seeds are ready to germinate, as immature seeds won’t sprout properly (we'll get into this below).

Types of Cannabis Seeds You Can Germinate

Before we go any further, we should note that there are three different kinds of cannabis seeds. These are:

• Regular cannabis seeds
• Autoflowering cannabis seeds
• Feminized cannabis seeds

Regular Cannabis Seeds

Regular cannabis seeds can become either male or female plants. Because male cannabis plants will naturally pollinate female plants, which will then develop seeds, cannabis cultivators will almost always separate the males from the females.

An unpollinated female cannabis plant will generally provide bigger and better yields. 

Autoflowering Cannabis Seeds

Autoflowering cannabis seeds will sprout into autoflowering marijuana plants. This means that these plants will automatically transition from the vegetative phase into the flowering phase without the grower needing to change the lighting conditions of their plants. 

If you're new to cannabis cultivation, it’s often recommended that you start with autoflowering cannabis seeds so you don’t need to worry about changing the photoperiods of your plants to get them to start flowering. 

Feminized Cannabis Seeds

Finally, feminized cannabis seeds will only grow into female marijuana plants. This is because these seeds are bred through botanical genetic manipulation to ensure the seeds cannot germinate and grow into male plants. 

Marijuana growers don't want male plants with their females because they will pollinate those plants and ruin the eventual cannabis yields.

But feminized seeds make this a non-issue. Without any plants growing into males, there's no need to separate any plants. 

What to Look for in a Seed Before Germinating

Regardless of what kind of cannabis seeds you choose to plant, there are a couple of things to look out for to ensure that they are ready and capable of germination. 

Generally speaking, the best seeds are darker in color. If you see dark stripes on your cannabis seeds (they may look like tiger stripes or blood vessels), the seeds are likely ready to germinate. On the other hand, if your seeds are pale, green, or white, chances are they aren’t ready to germinate. 

Seeds that are ready to germinate should also be relatively hard and solid. You should be able to pinch them between your fingers without them easily crumbling or breaking. If your seeds are too fragile, they're likely not the best for germinating. 

Of course, it's possible to skip the germination phase entirely by using cannabis clones. Clones are cuttings from a "mother" marijuana plant that, upon planting, will grow into another plant. Home cultivators can use their own clones, but you’ll need a “mother” cannabis plant to grow clones in the first place. Alternatively, you can purchase clones from some dispensaries, though seasonality and local regulations can make it easier to purchase seeds than clones.

What are the Critical Factors When Germinating Weed Seeds?

There are many factors at play during the germination of a cannabis seed. Unfortunately, even if your seeds are high-quality and healthy, some may not germinate at all. 

This is unavoidable to some degree. However, you can increase the number of seeds that sprout by keeping these influential factors in mind:

Temperature

One of the most significant aspects you'll want to keep an eye on is the temperature of your growing environment.

Cannabis seeds germinate best at a temperature range of 70 - 78°F, and it’s recommended to keep your growing environment between 74 - 78°F when germinating cannabis seeds. Temperatures below 70°F and higher than 90°F can disrupt the chemical processes necessary for successful germination.  

Moisture

Besides temperature, moisture is the next most important factor that affects seed germination.

While temperature first catalyzes the chemical reactions that take place, moisture allows the seed embryos to grow and expand, eventually breaking the seed shell to sprout into a seedling.

The seed will absorb some moisture in its environment during the imbibition process. It will expand as it does so, and the embryonic root – the radicle – will break through the seed shell and grow into the soil to absorb even more moisture for the rest of the seedling.

Too little moisture in your growing environment will prevent your seeds from germinating. However, too much water will cause your seeds to rot instead of sprouting.

The appropriate amount of moisture will ultimately depend on your choice of germination method. We cover this in detail below.

Lighting

Seeds typically sprout underneath the soil, which is inherently a dark environment. However, that doesn't mean you should neglect the lighting altogether.

Cannabis seeds do not take that long to germinate and become seedlings. You may find that tiny green sprouts emerge from your soil within a few days. Unlike the seeds themselves, these seedlings are hungry for light, and it's a good idea to have your lighting setup ready to go as soon as they emerge.

Marijuana seedlings grow best under blue light, like cannabis plants in the vegetative phase. Many cannabis cultivators rely on CFL grow lights when germinating their seeds for this reason.

How Long Does it Take for Weed Seeds to Germinate?

Like most seeds, weed seeds typically won't take very long to germinate. In most cases, seedlings will sprout out of their seed shells in 24 - 48 hours.

But don’t throw out your seeds if you don’t see a seedling in the first two days.

You may find that some of your seeds will take several days, or even a week, to sprout.

The Different Methods for Germinating Cannabis

Germinating Seeds Directly in Soil

Most cannabis cultivators germinate their marijuana seeds directly in soil as this method is ultimately the most effective and convenient way of popping seeds.

Cannabis seedlings fresh out of the seed are very fragile. By germinating seeds directly in soil, growers can sprout their seeds without moving them into a growing medium while potentially harming them in the process.

Materials:

• High-Quality Soil,
• Plant Pots or Germination Trays,
• Water.

Process to germinate cannabis seeds in soil:

1. Fill your plant pots or germination trays with moist, high-quality soil.
2. Make small holes 10 - 15mm deep in each pot or tray slot.
3. Place a cannabis seed into each hole.
4. Gently cover the seeds with the moist soil. However, be sure not to pack the soil down too tightly; it'll need to be loose enough to allow the seeds' roots and stems to expand.
5. Spray a small amount of water on the top of the covered seed to ensure the soil is moist (but not soaked through).

As we mentioned, ensure that your pots or germination trays are in an environment between 74 - 78°F. Also, be mindful of the humidity in your growing environment. If the area is too dry, your seeds may have more difficulty germinating.

If all goes well, your seeds should germinate within 24 - 48 hours. However, it may be another 3 - 7 days before you see a seedling emerge from the soil, so be patient!

Germinating Seeds with a Paper Towel

Another popular way of germinating cannabis seeds is on a wet paper towel. In fact, horticulturists – and even Creed from The Office – have long sprouted all sorts of seeds in this way.  

Materials:

• Paper Towels,
• Container,
• Water,
• Plant Pots.

Process to germinate cannabis seeds with a damp paper towel:

1. Place a paper towel within a container of your choice.
2. Put the cannabis seeds you wish to germinate on the paper towel,
3. Then, spray the seeds and paper towel with room temperature water,
4. Take your container and put it somewhere dark and warm,
5. Come back to the container periodically and spray with more water. The paper towel and the seeds must remain moist (but not soaking wet) until they sprout. Otherwise, they'll dry out and fail to germinate,
6. As soon as you see the seeds have sprouted and begun to grow into a seedling, you should remove them from the paper towel and place them in your growing medium.

So long as the temperature and moisture conditions are right, you should see your seeds break out of their shells within 24 - 72 hours. At this point, they’ll be ready to plant in soil, where they can grow into full cannabis plants.

When transferring the seeds to soil, be very gentle. These baby seedlings are incredibly fragile, and the stress from planting the germinated seed can kill the plant if you don’t handle them with care.

Germinating Seeds in a Glass of Water

It is also possible to germinate cannabis seeds in a glass of water. However, this is one of the most unreliable ways of doing so.

Materials Needed:

• Glass or Bowl of Water,
• Plant Pots.

Process to germinate cannabis seeds in a glass of water:

1. Fill a glass or bowl halfway with room-temperature water (around 71°F),
2. Place your cannabis seeds in the water,
3. Wait a few days for the seeds to germinate,
4. Prepare your plant pots with soil and make small holes around 10–12mm deep in each,
5. Once your seeds have sprouted, gently transport them into the holes in your pots,
6. Loosely cover the seeds with more soil and wait for your seedlings to grow further.

While it's possible to germinate your seeds this way, it’s more likely than other methods to result in too much moisture, which will cause seeds to rot instead of sprouting. As such, many home growers recommend germinating your cannabis seeds in soil or on a paper towel rather than a glass or bowl of water.

Germinating Cannabis FAQs

Why won't my seeds sprout?

There are many reasons your cannabis seeds could fail to germinate. Even in perfect conditions, your seeds are unlikely to germinate 100% of the time. However, if a majority of your seeds aren’t sprouting, there may be a problem with your growing environment (or your seeds).

A few common reasons seeds fail to germinate include:

• temperature may be too high or low,
• you may have too much or too little moisture,
• a fungus may have infected your seeds/soil,
• the soil might be too old,
• you might have planted your seeds too deep or packed the soil too tightly.

When is the best time to plant?

If you want to germinate cannabis seeds for outdoor cultivation, then it's best to start planting your seeds around the Spring Equinox (that is, around late March - early April). This will give your seedlings plenty of time to grow big enough for transporting outdoors and getting the most out of the annual growing season.

If you’ll be growing your plants indoors, the time of year doesn’t matter (as long as you have the right set-up for your home grow).

How do I store unused seeds?

Proper storage of unused cannabis seeds will depend on how long you intend to store them. If you want to hold onto your seeds for 6 - 12 months, you should place them in an airtight container and keep them somewhere cool, dark, and dry, such as your fridge.

If you want to keep your seeds for 12 - 16 months or longer, consider storing them in the same way but in the freezer instead.

Will damaged seeds still germinate?

It depends on how damaged the seed is and where. If the seed shell is cracked, the seed is unlikely to germinate.

What do I do if the roots grow upside down?

If you find that your seed's roots are growing upside down after germinating, meaning the root emerges out of the soil rather than the stem, gently remove it from the soil and flip it back. Be extra careful, as the seedling may not survive the handling and replanting.

When do I start feeding nutrients?

Young marijuana seedlings have enough nutrients provided by the seed themselves for their first few weeks of growth. And starting a nutrient regime too early can burn or kill the plant. Once the plant has begun its vegetative growth stage, typically around 3-5 weeks, you can start feeding nutrients.

The information in this article and any included images or charts are for educational purposes only. This information is neither a substitute for, nor does it replace, professional legal advice or medical advice, diagnosis, or treatment. If you have any concerns or questions about laws, regulations, or your health, you should always consult with an attorney, physician or other licensed professional.