If you've been contemplating growing your own cannabis plants, one of the first steps you'll need to do is germinate the seeds.
Below, learn about the germination process and how to germinate weed seeds using three tried and true methods.
What are weed seeds?
As with all angiosperms, or flowering plants, cannabis produces seeds that contain all the genetic information needed for growth and reproduction.
When a seed is planted, the translation of this genetic material dictates each unique physical characteristic the mature plant will have. If these are desirable traits, like potency; smell; vigor; etc., a breeder can select for these through a long process of genetic stabilization through generations, which eventually leads to the creation of a cultivar, or strain.
The anatomy of a weed seed
Weed seeds are about the size of a peppercorn, ovular in form, and pointed on each end with a ridge that transverses longitudinally on only one side from tip to tip. It is this ridge that opens up during germination. The opposite side is rounded.
The body of the seed is brown, but underdeveloped and unfertilized seeds can have an off-white color and are typically smaller in size. The body of a weed seed is spotted or striped, most commonly with light brown specks, but some varieties of cannabis can have red or yellow markings.
Plant embryos are contained within seeds and house all cells that will eventually differentiate into leaves, roots, and stems. Embryos, found within the reproductive organs, are protected by an outer envelope called the pericarp.
Crucial components of the plant embryo are cotyledons, the first leaves to appear from the seed, and the radicle, which develops into the primary root.
Once the seed germinates and begins its growth into a mature plant, special structures called root caps protect the growing tips of the plant.
How are weed seeds produced?
Cannabis seed production begins with the pollen grain of a male plant. From this grain, a pollen tube grows, producing male generative cells that disperse in the form of pollen.
The migration of pollen into a female plant ovule triggers pistils to fall off and seed production to begin. The bracts, which contain the ovule, will then fill with seeds.
For landrace strains in non-controlled environments, such as those that grow like common weeds outdoors in India and other places, cannabis plants will seed by the natural course of nature. Nowadays, growers will try to prevent that from happening since seeded buds are not a highlight the market. Pollination and seedlings should be dealt with in controlled environments.
What is germination?
In an environment with enough moisture, a weed seed will increase in size and slowly break out of its shell. A seedling — or “germ” — forms, then roots will emerge, helping the baby plant absorb nutrients from the soil. Seeds will naturally develop roots that face down and stems that stretch upwards, allowing young cannabis plants to feed off light and earth.
You can think of the seed as coming out of hibernation to start the growth process. Also known as "popping” seeds, germination begins when a seed receives environmental cues, such as an influx of moisture, which alerts it to when the setting and conditions are at the optimum time to start growing.
Why is germination important for weed seeds?
Germination is a crucial aspect of cannabis cultivation and steps can be taken to boost successful popping.
The environment in which seeds germinate plays a role in the outcome — every germination method requires proper moisture, minimal handling, and warm temperatures between 70 - 80°F. Some cultivators also improve germination attempts by soaking their seeds in 1% hydrogen peroxide or composting tea for 12 hours beforehand to kill pests. If you choose to use the peroxide method, ensure the seeds don't soak in it for too long, as it may burn them and render them useless.
It's essential to acquire high-quality cannabis seeds for germination, as these will become high-quality cannabis plants. Seeds that are too green indicate that they haven't reached full maturity, while pale-green, white, or very dark cannabis seeds may have trouble sprouting. But it's tricky to know the outcome of a popped seed, so try germinating multiples.
What kind of cannabis seeds can you germinate?
There are three types of cannabis seeds you can germinate:
- Feminized seeds: Bred to produce only female plants which deliver consumable flower. They can be transferred to a larger pot within four weeks. Females contain higher volumes of THC and other cannabinoids, which is one advantage of choosing these seeds. Feminized seeds make a lot of sense for those who don't have a large grow space since you won't be dealing with an influx of unusable male plants.
- Regular seeds: The most common type of seeds you can find at a dispensary or from a grower. Remember that unless the seeds are labeled as “feminized” and are from a reputable brand, you risk growing males, which can pollinate the female plants and wreck the crop. However, regular seeds are special because they can you open you up to the possibilities for breeding more genetic variation. Remember: if you're not trying to breed your cannabis plants, kill the male plants as soon as you see the pollen sacs.
- Autoflowering seeds: The most recommended for those dealing with shorter seasons — such as growers who live in hotter climates — autoflower seeds can survive in extreme climates and may even produce multiple harvests in the same season. Autoflowers will naturally switch from the vegetative stage to the flowering stage without the grower having to change the lighting or many of the growing conditions. Autoflower plants will flower in the same pot they are germinated. It's important to note that a possible disadvantage of autoflower seeds is their tendency to produce lower quality flowers which makes them less potent.
How to germinate weed seeds in soil
Soil is an easy, natural method to germinate cannabis seeds, and it protects fragile roots from interference. Another reason soil is a great method for germinating weed seeds is because it contains vital minerals and microbes that aid in plant development.
Fill a small pot, such as a 3.15-inch starter pot, with soil and keep it damp by lightly watering it without soaking. The pot must be small to keep the overall medium evenly saturated.
Be sure you start with the correct type of soil and that it is well-draining. Use gently fertilized potting soil or a seed starter with a pH level of approximately six, which contains the right acidity and enough nutrients to strengthen your young cannabis plants for the first two weeks.
Note: You do not need to add more nutrients to the soil, or you risk overfeeding and killing your seeds.
Use your finger or a pencil to push a small hole about an inch deep in the soil.
Insert the seed into the hole and cover it with soil.
From this point on, don't disturb the seed. The young plant is fragile and will position itself in the soil bed.
Situate your pots under a fluorescent lamp and lightly water with a spray bottle.
Note: Keep seeds away from the windowsill, as the temperature is too volatile for germination. You want to keep the temperature for germination between 70 - 80°F.
Monitor the soil every day and keep it moist. Within 4 - 10 days, tiny stems should start sprouting.
When the seedling stems reach 2 - 4 inches in height, transplant them into larger pots to give the roots room to spread down and out.
You've now successfully germinated your cannabis seeds into proper, young plants.
How to germinate weed seeds in water
Germinating seeds in water is faster than the soil method, but you must adjust your environmental factors accordingly.
Remember: successfully germinating seeds requires a perfect balance of growing conditions. When germinating in water, seeds will usually pop within 24 - 48 hours, though cultivators can keep them soaking for up to a week.
Water germination is quick since the seed gets a rush of moisture immediately. The shell also softens and cracks more easily after it's been soaking.
Fill a glass with tap water and let sit until it reaches room temperature or around 65 - 70°F.
Add 2 - 3 seeds per cup and let sit.
Watch for changes. The seeds should start sprouting in about two days, though older seeds can take up to a week to sprout.
Change the water to fresh tap water every two days. Ensure that it stays at room temperature.
Transplant the popped seeds to soil. You can remove them from the water and place them in the soil at any point once they've sprouted.
When the roots are about 5 millimeters long, they should be transplanted.
Note: The seeds are extra fragile at this stage, and any harm risks the development of your plants. Bury them gently and place the seeds root-side-down in the soil.
How to germinate weed seeds using paper towels
The paper towel method is another common way you can pop your seeds. Some will use this method with cotton pads instead of paper towels, but the necessary steps are the same.
Lay one paper towel on top of a clean countertop and sprinkle a few seeds on top. Cover them with another paper towel.
Use a spray bottle to spray water on the paper towels and gently place them in a plastic snadwhich plastic bag or Tupperware.
Maintain a temperature of around 72°F and keep the seeds in the dark and away from a windowsill.
In 2 - 5 days, the seeds will pop inside the paper towels and emit tiny roots ready to plant when they reach about 5 millimeters.
Transplant the popped seeds to soil. Use your hands or tweezers to gently remove each seed from the paper towels and place them in a prepared growing medium.
Note: Tiny roots can get tangled in the paper towels, so move the seeds to potting soil before the roots grow too long.
How long do cannabis seeds take to germinate?
The length of time it takes for seeds to germinate depends on the method you use.
However, no matter the method, most seeds will germinate in about four days, though sometimes it can take up to 10 days depending on the seed quality and environment.
Below are approximations of how long it will take for your seeds to pop:
- Soil: 4 - 10 days
- Water: 24 - 48 hours
- Paper towel: 2 - 5 days
Is it possible to speed up the germination process?
The fastest way to germinate seeds is by soaking them in water. As long as the seeds soak undisturbed, they should sprout within 24 - 48 hours with this method.
What should I do if the seed sprouts but the seed shell is stuck to the plant?
If your shell gets stuck to the plant, take a spray bottle and soak it with water. The extra moisture should soften the shell enough to remove it gently with your hands.
If the shell isn't properly soaked and you attempt to pull on or remove it, you risk ripping out or breaking the plant completely.
How long do cannabis seeds last in storage?
If you're not ready to pop your seeds, you can store them in a cool, dark place. The fridge is the most common place growers keep their seeds, storing them for 6 - 12 months in a small container. Though, they can be stored for years if the conditions are perfect.
You can also store seeds in the freezer for up to 16 months.
Why aren't my seeds germinating?
No matter what you do, sometimes seeds simply won't sprout. This can happen for many reasons.
Here are a few causes as to why your seeds aren't germinating:
- Your soil or paper towel is too dry. Try adding more water
- The seeds may be planted too deep or impacted by the soil
- Temperature is too low or too high. Optimal levels for germination fall between 70 - 80°F
- The soil or seeds may be infected with a fungus or plant virus
If you planted your seeds in soil and they haven't poked through by day ten, they likely didn't survive.
How deep should I plant cannabis seeds once they're germinated?
When your seeds pop, plant them about an inch deep in your soil. You can transplant them to a larger pot once they've sprouted and turned into starts.
Note: If you can see the roots coming back up through the soil, the seed is upside down. Gently — very gently — remove the seed and replant it.
Should you germinate seeds indoors or outdoors?
Whether you're planning an indoor cultivation or outdoor grow, it's best to germinate your seeds indoors since it's easier to maintain proper temperature, light exposure, and moisture.
Indoor germination, whether you use soil or paper towels, can ensure that your cannabis seeds have the best chance of survival. To germinate seeds indoors, use any of the methods described above, and within a few days, you'll have popped seeds ready to transfer to a growing medium either inside or outside.
Featured image by Gina Coleman/Weedmaps