How to germinate cannabis seeds
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- What is germination?
- Preparing to germinate cannabis seeds
- How to germinate cannabis seeds
- How do you germinate seeds indoors?
- Do you need to germinate seeds before planting?
So, you’ve decided to grow your own cannabis plants. You purchased a pack of seeds, assembled cultivation materials, cleared a space in your garden, and are ready to grow your first cannabis crop . With everything in hand, it’s time to begin the very first step of cannabis cultivation : germinating seeds.
What is germination?
Germination is the first stage of the cannabis growth cycle : the process that brings a cannabis seed out of its hibernation period and starts the cannabis growth process. After all, seeds in a bag don’t spontaneously start developing roots. Also known as “popping” seeds, seed germination begins when a seed receives environmental cues letting it know the setting is perfect to start growth.
Germination is the process that brings a cannabis seed out of its hibernation period and starts the cannabis growth process. Photo by: Gina Coleman/Weedmaps
When a seed enters an environment with enough moisture, it will increase in size and slowly break out of its shell. A seedling or germ forms from which roots will emerge, helping the baby plant absorb nutrients from the soil. Seeds naturally develop roots facing down and stems stretching upward, allowing the young cannabis plant to simultaneously feed off light and earth.
It’s essential to acquire high-quality cannabis seeds for germination, as these will go on to become high-quality cannabis plants. Seeds that are fresh-feeling or too green indicate that they haven’t reached full maturity, while pale-green, white, or very dark cannabis seeds may have trouble sprouting. However, it’s tricky to know the outcome of a popped seed, so trying may be worthwhile. If you’re not ready to pop your seeds yet, store them in a dark, cool place until it’s time for germination.
Preparing to germinate cannabis seeds
Germination itself is a crucial aspect of cannabis cultivation. The seed germination process is the foundation of every marijuana plant, and steps can be taken to boost successful popping. For example, some cultivators improve germination attempts by soaking seeds in 1% hydrogen peroxide or a compost tea for 12 hours beforehand to kill any dangerous pests.
The environment in which seeds germinate also plays a role in the outcome. While there are several different germination methods, each requires proper moisture, minimal handling, and warm springtime temperatures between 68-72 degrees Fahrenheit.
How to germinate cannabis seeds
The best germination method depends on the cultivator’s choice. Here are some of the most common ways to pop your cannabis seeds.
How to germinate seeds in soil
Soil is an easy, more natural method with which to germinate your cannabis seeds. The soil protects the fragile roots from any interference, and soil is, after all, where a cannabis plant would grow in the wild.
Soil is an easy, more natural method with which to germinate your cannabis seeds because the soil protects the fragile roots from any interference. Photo by: Gina Coleman/Weedmaps
First, make sure you use the correct type of soil, either gently fertilized potting soil or a seed starter with a pH level of approximately six (6). The soil contains the right acidity and enough nutrients to strengthen your young cannabis plants for the first two weeks. Be careful not to add more nutrients, or you risk overfeeding and killing your seeds.
Place the soil in a small pot and use your finger or a pencil to push a small hole in the dirt, a bit more than half an inch deep. Insert the seed into the hole and bury it with soil. From this point on, don’t touch your seed. The young plant is fragile and knows how to position itself in the soil bed.
Gently water the soil with a spray bottle and situate your pots under a fluorescent lamp. Keep seeds away from the windowsill, as the temperature is too volatile for germination. In general, you’ll want to keep the temperature in the range of 70 to 80 degrees Fahrenheit.
Monitor your soil every day and keep it moist. Within four to seven days, you should see tiny stems sprouting from the soil.
When the seedling stems reach two to four inches in height, it’s time to transplant your cannabis into larger pots with more room for roots to spread down and out. After you’ve done this, you’ve successfully germinated your cannabis seeds into proper, young plants.
How to germinate seeds in water
You can also germinate your seeds by placing them in water. It’s slightly faster than the soil method, but you need to adjust your environmental factors accordingly. Remember, successfully germinating seeds requires a perfect balance of ideal growing conditions. When germinating in water, seeds need only 24-48 hours to pop their stems, though cultivators can keep them soaking for up to a week as needed. Water germination is faster because the seed gets all the moisture it needs immediately, and the shell softens and cracks more easily after soaking.
To employ water germination, fill a glass with tap water and let it sit until it reaches room temperature or around 65 degrees Fahrenheit. Add two to three plant seeds per cup and allow them to sit, watching for any changes. Change the water to fresh tap water every two days, making sure it stays at room temperature.
The seeds should start sprouting in about two days, though older seeds can take up to a week to sprout. You can remove them from the water and place them in the soil at any point once they’ve sprouted. Once the roots are about five millimeters long, they need to be planted.
The downside of water germination is that once they’ve popped, you’ll need to maneuver them into their growing medium manually. This is a delicate process, as germinating seeds are extra fragile, and any harm risks the development of your plants. Make sure to place the seed roots down in the soil when you transfer to a pot.
How to germinate seeds using paper towels
The paper towel method is also a common way cultivators pop their seeds. Some even use this method with cotton pads instead of paper towels, but the necessary steps are the same.
To germinate seeds this way, lay one paper towel on top of a countertop, place a few seeds, and cover them with a second paper towel.
Lay one paper towel on top of a countertop, place a few seeds, and cover them with a second paper towel. Photo by: Gina Coleman/Weedmaps
Use a spray bottle to moisten the paper towels and then store the cushioned seeds between two plates, under a face-down bowl, or gently place them in a plastic bag. Maintain a temperature of about 72 degrees Fahrenheit, keeping the paper towel wrapped seeds in the dark and away from a windowsill. In two to five days, the seeds will pop inside the paper towel sandwich and emit tiny roots, ready to plant when they reach about five millimeters in length.
Use a spray bottle to moisten the paper towels and then store the cushioned seeds between two plates, under a face-down bowl, or gently place them in a plastic bag. Photo by: Gina Coleman/Weedmaps
The paper towel method also has its risk, as the fragile seedlings can be damaged during the potting process. The tiny roots can also get tangled in the paper towels, so make sure to move the seeds to potting soil before roots grow too long. Use your hands or tweezers to gently remove each seed from the paper towels and place them in a prepared growing medium.
How do you germinate seeds indoors?
Whether you’re planning an indoor cultivation or outdoor grow, it’s best to germinate your seeds indoors. It’s easier to maintain proper temperature, light exposure, and moisture inside, and you can protect your seeds from the elements. Indoor germination, whether using soil or paper towels, will ensure your cannabis seeds have the best chance for survival.
To germinate seeds indoors, use any of the methods described above. Within a few days, you’ll have popped seeds ready to transfer to a growing medium.
Do you need to germinate seeds before planting?
While many plants can be germinated in the ground, cannabis seeds are fragile enough that you should germinate them before planting.
Once your seeds have sprouted roots, they should be planted in soil, a soil-less medium, or in your hydroponic setup. Make sure not touch the root, caring for and navigating the seedling so that the roots face downward. Plant the seed about one inch deep in your growing medium, cover lightly, and allow for about a week for the seed to emerge from the soil. If the seed hasn’t poked through by day ten, it likely didn’t survive.
How to germinate cannabis seeds Copy article link to clipboard. Link copied to clipboard. Contents What is germination? Preparing to germinate cannabis seeds How to
How to Germinate Seeds via Paper Towel Method
Cannabis seeds are natural things and you can’t expect 100% germination every time. Unfortunately, that’s just not how nature works. Many factors can affect germination including genetics (some strains germinate easier than others), the age of seeds, and how well they were stored. But I’ve been lucky and gotten 100% germination ever since I started using this method.
Paper Towel Method – Germinate seeds between wet paper towels, lock in the moisture with two plates, and place on a seedling heat mat for a few days
- High Germination Rate – Almost every seed with germinate if you follow the instructions
- Fast – Often takes only 1-3 days to see roots
- Keep Track – You can check on seeds without disturbing them
- Less Space – Use less space than planting seeds in pots (helpful if germinating lots of seeds at once)
- Fun – I personally love seeing the whole germination process and it makes me genuinely feel closer to the seedlings
- Multiple Steps – Not as simple as planting seeds directly in soil!
- Requires Supplies – You need cheap paper towels, seedling plugs, and a seedling heat mat
- “Bucket Head” Seedlings – I’ve found that shells are more likely to get stuck on the seedling leaves with this germination method because seedlings aren’t pushing themselves out of the soil. You may want to use tweezers to remove the shell gently, or just leave them be. However, this can happen with any method (instructions at the end of the article explain how to remove stubborn shells safely) and I personally find the increased germination rate makes this worth it.
Seeds typically germinate in 1-3 days!
Create happy little seedlings in less than a week!
How to Germinate via the Paper Towel Method
- Cheap paper towels – Why cheap paper towels? Seed roots grow into expensive cloth-like ones and have to be cut out (learned that one from experience)
- Two Plates – You need to lock the moisture in during the germination process
- Cannabis Seeds – If you need seeds, here’s a list of seed vendors that ship worldwide
- Rapid Rooters with Tray – The perfect environment for newly germinated seeds
- Seedling Heating Mat – Or any warm surface that stays about 70-85°F (20-30°C) to keep seeds warm
Cheap paper towels (don’t use the expensive cloth-like ones!)
Rapid Rooters (note: extra Rapid Rooters can be stored in a cool place for future grows)
Seedling Tray to hold Rapid Rooters
Seedling heat mat to keep seedlings warm (or any surface that’s about 70-85°F or 20-30°C)
1.) Put 3-4 Layers of Paper Towels on Plate
You don’t want to load your plate up with tons of paper towels, but it’s nice to have several sheets so they can hold plenty of water. If necessary, fold or cut the paper towels to size so everything fits completely inside the plate. If a paper towel is sticking outside the plates, everything will dry out quickly.
You may need to cut (or fold) paper towels so they fit completely inside plate
2.) Label the Strains
If growing more than one strain at a time, label the paper towels so you’ll know which seed is which.
3.) Add Water & Seeds
Add some water on top of the paper towels so they’re soaked through, then place seeds down. I add water first to avoid accidentally moving seeds. It’s also a good idea to keep the plate flat so seeds don’t roll around.
4.) Cover with 1 Sheet of Paper Towel
Put a single sheet of paper towel on top. With just one sheet you will be able to see whether the seeds have germinated without having to disturb them. You may need to add a little extra water so that the top sheet is moist all the way through.
With a single sheet on top, you can still mostly see the seeds
5.) Put 2nd Plate on Top
Lock in all the moisture by putting another plate on top.
6.) Place on Seedling Heat Mat
Plug in your seedling heat mat. It should warm up quickly. I’ve put the plates directly on the mat before, which worked well, but sometimes I worry my little weed seedlings may get too hot with the plate directly on the mat. Since I already have a Rapid Rooter tray for later, I place it between the mat and the plate. Feel free to use something else like a book or towel. The basic idea is to put some space between the heating mat and the plate so the plate still gets warm but the extra air space keeps the heat nice and even.
Why a seedling heat mat? Seeds germinate significantly faster when they’re kept 70-85°F (20-30°C). A seedling heat mat keeps seeds warm during the germination process. However, any warm spot works just as well (for example, on top of the refrigerator is the perfect temperature for some people). When you touch the wet paper towels, they should feel warm but not burning hot.
7.) Check on Seeds at Least Once a Day
Ensure paper towels don’t dry out. You may have to add more water occasionally to keep them wet. You can usually tell when the seeds have germinated without looking under the top sheet. This means you can check on your seeds regularly without disturbing them by picking up the top plate.
Seeds typically sprout in 1-3 days. Certain strains and older seeds may take a few extra days.
8.) Put Germinated Seeds in Rapid Rooters
Once seeds have germinated, gently pull off the top paper towel to reveal the seedlings underneath.
Carefully and slowly remove top paper towel sheet
Did you know the first two round seedling leaves were already fully formed inside the shell? The germination process only releases them. New leaves are yellow at first but turn green once they start getting light.
At this point, you may see some seedling leaves have already broken free of their shells. That’s awesome. These seedlings often grow the fastest.
If there’s a short root or seedling hasn’t germinated yet, put the paper towel back and gave the seedling one more day. Seedlings grow faster if they have a bit more root before being planted.
This Critical Purple Kush seed took an extra day to germinate compared to the other seeds. I gave it one more day after this so the root could get longer before I put in a Rapid Rooter.
I recommend cutting your Rapid Rooters in half to make it easier to place germinated seeds. Even a seed with a long wiggly root will usually easily fit into the “crack” of the Rapid Rooter. This prevents you from bending the roots.
Cut Rapid Rooters in half to make it easier to insert germinated seeds
Try to place the seed head close to the top so they don’t have far to go. I’ve found that some seedlings don’t make it to the top if you put them too far down.
If the seedling has already lost the shell, place the leaves close to the top. These seedlings often grow the fastest.
Otherwise, add the seedling, root down, with the shell close to the surface
Gently close around the seedling
Put into the Rapid Rooter tray (make sure they’re moist all the way through!) The bottom shell of the tray will hold extra water so plugs don’t dry out.
Add enough water that all the Rapid Rooters appear dark, but not shiny from too much water. Once you’re done, put the trays back on the seedling mat. Young seedlings love warmth!
9.) You Have Seedlings!
The leaves should appear above the Rapid Rooters within a day or two.
Just 12 hours later, several seedlings have already appeared above ground.
At this point, the seedlings are ready to be put under a gentle light. A sunny window works well, though your regular vegetative grow light should be fine as long as you keep it twice the normal distance away. Avoid touching the seedlings if possible. This is when they’re most vulnerable.
Within a day or two under a light (or in a sunny window), you’ll have a bunch of happy seedings!
The seedlings are ready to go in plant containers once they’ve spread out their first set of serrated leaves (to about the width of the Rapid Rooter)
At this point, you can plant the whole Rapid Rooter. Don’t forget to label the strains!
Move the grow light down to the standard distance once the plants have 3 sets of leaves. By now they should be growing fast!
Note: Move grow light down early if seedlings start getting tall with long stems. Tall, stretchy seedlings are telling you they want more light.
What If the Seedling Shell Gets Stuck? (“Bucket Head” Seedlings)
One downside to this method is sometimes a seed shell will get stuck on the seedling. Here’s how to deal with that.
Helpful Tool: Pointy tweezers (though most tweezers will work in a pinch)
Sometimes leaves get stuck in the shell. Here’s what to do.
First, give the seedling 24-48 hours to see if it pushes the shell off on its own. Many seedlings just need a little extra time and don’t need your help.
Ignore stuck shells if the leaves are already free. The shell will fall off on its own.
If you don’t see any progress and leaves still seem trapped after a day or two, you may need to remove the shell to release the leaves contained inside. If leaves can’t break free and see the light, the seedling may die.
Close tweezers so they are as narrow as possible and put inside the crack. Then slowly allow tweezers to open, which will gently pry the shell apart.
I used to use my fingers to remove shells but it can be hard not to disturb the seedling. Then I learned that a pair of pointy tweezers can be inserted into the crack and allowed to gently open to pry the seed apart. Don’t tug or use any force whatsoever. Just gently and slowly release the leaves. The leaves may be stuck to the shell at first and it can take several seconds of gentle tugging for the leaves to slowly loosen and pull away from the shell. If you’re having trouble, add some water to the stuck part and wait a few minutes to help soften it up.
If the seedling leaves aren’t opening up because they’re stuck inside the seed membrane, wet the membrane and give it a few minutes soften up. Then use tweezers to gently remove the membrane. In some cases, it’s easier to stick the tweezers inside and pry the leaves apart just like with a shell.
If leaves are stuck inside the shell membrane for more than a day or two, do this: Wet the membrane, wait a few minutes, then use tweezers to gently pry it away from leaves.
Once you can see the two individual leaves are separated, you’re good to go!
No germination method is perfect (some seeds just won't germinate), but I've gotten 100% germination ever since I started using this method.