Cannabis Seeds Germination
Cannabis seeds germination is the process of getting your seeds to sprout, and you know sprouting has occurred when a little white tendril pops out of the seed.
The little white tendril that emerges from a cannabis seed during germination is your plant’s first root, known as a “taproot.” All other roots made by your cannabis plant in its lifetime will sprout from the taproot.
The taproot – and maybe a few tiny early offshoots of the taproot – will get longer and longer, pushing the seed up, and after the shell breaks through the surface of your growing medium, the first leaves (these first round leaves are known as “cotyledons”) will emerge from inside the cannabis seed.
The cotyledons were already created as part of the plant embryo in the seed itself, so the cannabis seedling doesn’t have to grow them. In fact, the emerging first leaves are what break apart the shell after it’s cracked open by the taproot, as pictured here.
The next set of leaves after the cotyledons are your plants first “true” leaves and will have jagged edges (serrations). At least, they are the first leaves that your seedling cannabis plant has grown all on its own, unlike the cotyledons which were already formed in the seed.
Marijuana seeds need the following to get the best germination rates:
- Moisture – Keep things moist but not soaking (you can soak hard seeds for up to 24-32 hours, but do not leave seeds soaking in water for longer than that).
- Peace – Seeds need to be left alone while you’re waiting for the taproot to show up.
- Warmth – Keep things warm to get the best germination rates, but not too hot! Think springtime. Seeds can definitely germinate in cooler temps, but germination tends to take longer when it’s cool.
- Gentle – Be careful when checking seeds, and treat them gently when you have to move them. Avoid touching their white root if possible; the taproot is very fragile and easily snaps off!
- Plant Root Down – When planting germinated seeds, point the white root downwards into the growing medium to prevent the seedling from having to reorient itself.
- Plant Knuckle Deep – When planting germinated seeds, they don’t have to be placed too far under in the growing medium, about a half inch to an inch (1.3 cm – 2.5 cm) down from the surface of the medium should be enough.
Never let your young sprouted seeds dry up
The main signal that tells a marijuana seed to start sprouting is the presence of moisture and heat. The combination of warm and wet (aka spring conditions) “tells” the seed to start burrowing their main root (called a taproot) through their shell.
If a seed’s root breaks through the shell and the water around has dried up, your seedling will die. Plain and simple.
Seedlings are fragile at first. Once sprouted, the roots need to stay constantly moist to stay happy and healthy. It’s important to make sure the seeds have access to water the entire time during germination, no matter which cannabis germination method you end up using.
Keep things warm
Seeds germinate best in warmer temperatures and young marijuana seedlings do better with higher relative humidity in the air. When seedlings are young, they grow faster and healthier when they can absorb moisture from the air through their leaves while their roots are still developing. Dry air won’t kill your seedlings, but it doesn’t make things better. Again, think springtime conditions.
Germination Method 1: Starter Cubes & Seedling Plugs
One of the best cannabis germination methods is to use specifically-made starter cubes and seedling plugs. These plugs make cannabis germination easy. You simply place the seed in the cube or plug, add water as directed, and seedlings automatically get the perfect conditions for germination.
Each cube or plug already has a hole specifically for you to place your seed.
This is one of the easiest germination methods, and doesn’t leave a lot of room for error. Cannabis seeds and clones can be expensive, and sometimes we have genetics we just can’t afford to lose. When that’s the case, germinate your cannabis with one of the following recommended options to ensure as close to 100% germination rate as possible.
It’s often hydroponic cannabis growers who use rockwool cubes since these can be safely placed in hydroponic setups, hold a lot of moisture, and are resistant to mold. Rockwool is cheap and easy to find. It comes in convenient cubes. But it does have some major drawbacks…
Pros of Rockwool
- Cheap & Easy to Find
- Inert Medium (useful for hydroponic growers)
Cons of Rockwool
- Bad for the environment (unnatural material that does not break down)
- Bad for your health (especially your lungs) – wear gloves and cover your mouth/eyes when handling rockwool
- Has a pH that is too high for cannabis, so it must be thoroughly rinsed and treated
- Poor cloning and germination rates
- Difficult for new growers
Rockwool cubes are bad for the environment
Rockwool is not a natural material – it’s made by heating rock and chalk to 3,000°F and air is blown through the mixture to create thin fibers of rocky material
It does not break down naturally and therefore after rockwool is created, it will remain in that form basically forever, filling up landfills without breaking down for thousands of years.
Rockwool cubes can be bad for your health
Rockwool is dusty and needs to be rinsed thoroughly before use. Little pieces of rockwool and dust can easily get in your eyes, skin and mouth. Small strands or fibers can get lodged in your lungs if you breath in rockwool dust, and it’s unknown if these fibers can ever get out again.
Protect yourself! Always use a mask, goggles and gloves when working with rockwool.
Rockwool cubes have a high pH until they’re treated
New rockwool cubes have a high pH – too high for healthy cannabis seed germination. Therefore it’s important to thoroughly rinse rockwool cubes in pHed water, then let them soak in pHed water overnight before use. Since rockwool holds onto a lot of water, after soaking they should be given a few days to dry out before planting seeds or making clones.
Rockwool cubes do not get great germination rates
Rockwool can be difficult to germinate marijuana seeds in, so I recommend most beginner growers sprout their seeds using another method like Rapid Rooters (mentioned above) which can also be used in hydroponic applications but are less prone to germination problems.
Many growers have placed seeds in rockwool cubes, only to wait for weeks and never see seedlings appear.
Some growers seem to have no problems, yet many other growers suffer through very poor germination rates. Some seed companies will not honor seed germination guarantees if the grower uses rockwool, because it is notoriously bad for germination.
Germination Method 2: Plant marijuana seeds directly in growing medium
Sometimes nature’s way is the easiest way. In nature, marijuana seedlings would sprout in soil, and they would emerge as their taproots start growing down.
As a grower, you can also plant your seeds directly in your final growing medium. This works in all growing mediums, though some can be tougher than others.
One of the biggest benefits of planting your seed directly in the growing medium is you don’t have to worry about shocking your young seedling during transplant. Because your seed is already in its final resting place, your new seedling will immediately start adjusting to the environment. Every time you transplant a sprouted seed, it can cause stress as the young plant needs to readjust its new surroundings.
- Soil – Plant seeds a knuckle deep (0.5-1 inch OR 1.3 cm – 2.5 cm) in moist yet not soaking soil. Use a light or a heating pad to keep things warm. This is one of the easiest marijuana germination methods for beginners.
Germination Method 3: Germination Station
One option for growers is to use a tool which has been specifically designed to provide optimal germination conditions like this germination station with heat mat.
You can make a DIY germination station at home by putting a plastic dome over a plate on a heating pad.
There are benefits to the professionally made germination stations as they work very well and are pretty cheap to buy.
When growers start their cannabis seedlings in a germination station, the seeds are usually germinated in a starter seedling cube.
One of the advantages of starting seeds in starter cubes is your sprouted seeds can easily be transferred right to their next growing medium or container.
I recommend Rapid Rooters as these starter cubes work great for cannabis seeds and can be used in any growing medium including hydroponics, soil, or coco coir. Other starter cubes include Jiffy Peat Pellets, and Rockwool cubes.
Jump back up to the section about different starter cubes
Once your seed has sprouted, just make a little hole in your growing medium, and place the entire pellet inside. Make sure growing medium is also moist yet not soaking, like your pellet or cube. The roots will emerge from the bottom of the cube and burrow directly into your growing medium.
Germination Method 4: Soak Marijuana Seeds in Water Overnight
Another method to germinate marijuana seeds is to soak them overnight in slightly warm water, usually done in a glass drinking cup.
This method is especially effective for seeds which have extra hard shells, or seeds which are older (more than a few years old).
The warm overnight soaking can help “wake up” older seeds.
Most viable seeds will start out floating, and then eventually sink to the bottom of your glass after a few hours of soaking. If soaked in a clear drinking glass, you will see when the little white tap root first breaks through the shell. Some seeds take longer than others to sprout. Especially older seeds tend to need longer to pierce through their shell. However, if seeds are left soaking too long, and haven’t yet sprouted, they can drown. Therefore, do not leave seeds soaking in water for more than 24-32 hours.
Germination Method 5: Paper Plate Method
One way to germinate seeds is to wet a paper towel and then fold your seeds in it, then leave the paper towel in a warm place.
If you germinate your seeds in a paper towel, there is the risk of hurting the tap root (the little white root that grows out of your seeds) when moving the sprouted seeds so make sure you are careful when you’re checking to see if the seeds sprouted.
There is also the possibility of having the towel dry out which will kill your new seeds so I recommend putting your paper towel under an upside down bowl or between two paper plates.
How to Plant Your Germinated Cannabis Seeds
After you see that your cannabis seeds have sprouted, you should plant them right away.
You don’t want to touch the little white taproot with your fingers, so either carefully move the seeds, or use twissors. If you do touch or break the root, the seedling may still survive, but any damage to the root will definitely stunt and slow down growth right in the beginning.
Plant seeds so that the white root faces downward, about a knuckle deep.
The top of the seed should be just below the surface of your growing medium.
It can take anywhere from a couple of hours to a couple of days before you see the young seedling emerge from the soil or growing medium. If your marijuana seedling hasn’t sprouted from the soil within 10 days after being placed root-down, it probably isn’t going to make it 🙁 Even with the best practices and the best seeds, you will occasionally lose a seed. Many times it has nothing to do with you!
First sign of a taproot – the white root is burrowing down and soon you’ll see leaves emerge out of the seed as it stands up and starts growing!
12 hours later
Sometimes the shell can get stuck on the seedling, but it will almost always fall off on its own.
Within the first week of germinating seeds, you will notice that some seeds germinate right away and others take a little bit longer. This can be caused by a lot of things, from the age of the seed (old seeds have worse germination rates and tend to take longer) to simple chance. The amount of time does not necessarily have anything to do with how healthy your plant will be in the long run.
Once your seeds are safely planted, you can turn on your grow light. The heat from the lamp improves germination rates, and the light can help your new cannabis seedlings open their first set of leaves. In fact, the first set of leaves will often stay yellow until they get light.
If you will be transplanting your seedlings again, avoid transplanting until they are well established and have a couple of sets of leaves (nodes). Some growers will plant seedlings in a growing medium in a solo cup or peat pot, so they can just cut away the cup for easy transplanting.
When you move seedlings around a lot, it stresses them out and potentially stunts their growth. Too much stress can even kill them. So try to plan from the beginning so that you move your seedlings around as little as possible. once they get bigger, they are a lot more hardy and can stand a lot more stress and movement.
When the seed end is still bent down, all you see is a U-shaped stem/root
Cannabis seeds can look a bit different when germinating. When in doubt, always wait a few days to see if leaves appear before you try to interfere.
Sometimes the stem of a brand new cannabis seedling can look like the roots growing out the top. But if you wait and watch, you’ll see that it’s all part of the plan. Hope these pics help someone!
Sometimes you’ll see what appears to be roots emerging from your cannabis seed, but this is actually the stem. The stem pushes the seed and leaves up, and the main taproot is currently burrowing down to support the seedling
As the seedling emerges you’ll be able to see the leaves (sometimes it will still have the seed stuck on the first leaves, like in the picture above).
The cotyledons (first, round leaves) unfurl, and then the regular cannabis leaves between to grow. Here’s another view of that same seedling from above. Even though it may have looked a bit weird at first, this seedling is completely normal and will grow just fine from now on.
What Size Pot Should I Use?
When growing cannabis plants in a container, you have to choose the size of your pot.
A general guide is to have about 2 gallons per 12″ of height. This isn’t perfect, since plants often grow differently, but this is a good rule of thumb.
When in doubt, get a bigger final container size as opposed to a smaller one. Plants that get root bound from being in a too-small container will grow more slowly and be prone to problems. It’s not good to transfer plants during the flowering/budding stage, so you want to have your cannabis plants in their final container at least 2 weeks before the beginning of flowering/budding.
Final Container for Desired Plant Size – General guide
12″ ~ 2-3 gallon container
24″ ~ 3-5 gallon container
36″ ~ 5-7 gallon container
48″ ~ 6-10 gallon container
60″ ~ 8-10+ gallon container
But what size pot should you use for your seedlings?
For fastest growth rates, it’s better to plant young seedlings or clones in a very small container, like a disposable plastic solo cup.
For new seedlings and clones, use a small container if possible
The reason you want to start with a small container is that your plant’s young roots thrive on oxygen. Cannabis plant roots “breathe” oxygen, just like we breathe air, and it’s important that young cannabis roots get plenty of oxygen so the plant can grow as fast as possible.
However, young plant roots do not drink much water yet. When you water seedlings or clones in a very big container, they will use up all the oxygen quickly, and the large size of the container will prevent the growing medium from drying out.
A big plant will drink up all the water quickly, but with seedlings, you’re basically waiting for the growing medium to dry out by itself. While you’re waiting for the container to dry out, your cannabis roots are sitting in a wet environment and not getting much oxygen, slowing down their growth rates.
Poke holes in the bottom of your cup so water can drain out easily
By planting young seeds in a small container with holes in the bottom, the growing medium will dry out much more quickly, allowing you to water more often. The young cannabis will get plenty of oxygen and water.