How to germinate cannabis seeds
Germination is the process in which a new plant begins to grow from a seed. Also referred to as “popping,” germination is the very first step in starting your cannabis garden.
Cannabis seeds can be acquired from an array of sources and can vary in quality. For more info on how to buy marijuana seeds, check out our Guide to buying cannabis seeds.
When acquiring seeds, you want to make sure they are matured and that they appear dark brown with lighter accents and a hard feel. You don’t want a seed that feels fresh and looks green, which indicates that the seed hasn’t reached full maturity.
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Once you have your cannabis seeds, make sure you have the space necessary to allow your plants to grow and be healthy. Don’t pop seeds when you are unsure of your grow space, time availability, or intention with your garden.
Check out these additional resources for more info on cannabis seeds:
What’s the best way to germinate cannabis seeds?
Cannabis seeds require three things to germinate: water, heat, and air. Because of this, there are many methods to germinate your seeds. The most common and simplest method involves the use of paper towels saturated in water.
For this method you will need:
- Two clean plates
- Paper towels
Take four sheets of paper towels and soak them with distilled water. The sheets should be soaked but shouldn’t have excess water running off.
Take two of the paper towels and place them on a plate. Then, place the cannabis seeds at least an inch apart from each other and cover them with the remaining two sheets of water-soaked paper towels.
To create a dark, protected space, take another plate and flip it over to cover the seeds (like a dome).
Make sure the area they’re kept in is warm, somewhere between 70-90°F.
After these steps have been completed, it’s time to wait. You can check the paper towels to make sure they’re still saturated, and if they seem to be losing their moisture, you can apply more water to keep the seeds happy.
Some seeds germinate very rapidly while others can take several days. You know a seed has germinated once the seed splits and a single sprout appears.
This is the taproot, which will become the main stem of the plant, and seeing it is a sign of successful germination. It’s important to keep this area sterile, so don’t touch the seed or taproot as the seed begins to split.
Transplanting germinated cannabis seeds
Once you see the taproot, it’s time to transfer your germinated seed into its growing medium. Small 2-inch pots are a good place to start.
Fill the pots with loose, airy potting soil and poke a hole in the middle about a quarter-inch down using a pen or pencil.
To transfer the seed, use a pair of tweezers to gently pick it up, then drop the seed in the hole with the taproot facing down. Lightly cover it with soil.
Next, you’ll need to water the soil. Initially, use a spray bottle to provide moisture without over-saturating the soil. You want to give the seed water, but over-watering can suffocate and kill the delicate sprout.
Pay attention to the temperature and the moisture level of the soil to keep the seed happy, and within a week or so you should see a seedling begin to grow from the soil.
Germinating seeds doesn’t always go as planned. Some seeds will be duds. Others will be slow and take longer to sprout. But some will pop quickly and grow rapidly.
This is the beauty of seeds—often, you can tell which plants or genetics will thrive right from the get-go. This will help you determine which plants you want to take cuttings from for clones and which to breed with other strong plants to create a seed bank of your own.
Follow these simple steps on the best way to properly germinate your cannabis seeds, and find out how to transplant the seeds to soil after germination.
Seeds that Need Light for Good Germination
The Spruce / David Karoki
Starting seeds is not complicated, but you do need to know what conditions the seeds you’re planting need. Many gardeners are unaware that some seeds require light to germinate and covering them with soil will inhibit their sprouting.
There’s a general seed planting rule that says you should plant a seed to a depth that is three times its thickness. That means fat bean seeds should be planted one to three inches deep and tiny carrot seeds should barely be covered. Most seed packets will take the guesswork out of the process and tell you how deep to plant the seeds. It’s a good idea to follow these recommendations because a seed that is planted too deeply might not have enough stored energy to push itself above the soil line.
There’s an exception to every rule, though. Some seeds need the stimulus of light hitting them before they will break dormancy and start to germinate. Very often it is seeds that self-sow that require light. These plants, such as balloon flower (Platycodon grandiflorus) and poppies, drop their seeds on the soil and they germinate where they land. They sprout in response to environmental factors, including having the light hit them.
Seeds That Need Light to Germinate
There are several seeds that germinate best when they are exposed to light. If these seeds are covered in soil, chances are they will remain dormant and not sprout until conditions improve. It seems counterintuitive not to bury seeds, but these seeds should only be pressed onto the surface of the soil and kept moist to germinate. They include:
- Balloon flower
Seeds That Will Germinate With or Without Exposure to Light
While most plants that self-sow in your garden are able to germinate without being covered with soil, that doesn’t necessarily mean they absolutely need light. Some plant seeds are indifferent to light exposure and simply need to make contact with soil, whether it is underneath them or covering them. Flowers such as alyssum and cosmos will self-seed during their current growing season as well as the next one, whether or not they are exposed to light. Other seeds that will germinate uncovered include:
- Cole Crops
Although the seeds listed above do not require a covering a soil, you will probably get better germination if you follow the recommended planting depth because it will be easier for you to keep them moist and safe from hungry birds.
Keeping Seeds Moist When Exposed to Sunlight
Being able to sow seeds on the surface of soil makes planting easier, but keeping them moist until germination can be difficult since they are exposed to more than just light. Animals, wind, heavy rain, and digging gardeners can all disturb or remove seeds from your garden. If you are growing your seeds in flats or containers, you can cover them lightly with plastic wrap, plastic domes, or tuck them inside of clear plastic bags. They will still be exposed to sunlight, but they will not dry out as quickly as if they were left open to the elements.
For seeds directly sown outdoors, another option is to cover the seeds with a thin layer of fine vermiculite, a naturally occurring mineral with water-holding properties. Vermiculite is porous enough to let the light shine through while retaining enough water to stay in place and keep the seeds and soil under it moist. It can usually be found near seed-starting supplies; look for finely ground horticultural vermiculite, as other types are not suitable for gardening.
This may all sound complicated, but most seed packets will tell you exactly what you need to know. And remember, seeds have been sprouting for millennia without a lot of fuss––it’s just nice to give them the best chance possible by providing them optimal conditions so they can thrive.
Some plant seeds need exposure to light to germinate and should not be covered with soil. Here are some tips for starting seeds that need light.