Germinating cannabis seeds in soil is a traditional practice that connects your grow with the cycles of nature. Here, we’ll examine the reasons behind it and best practices for starting weed seeds in soil.
TL/DR
If you plan on growing cannabis in soil, start in soil.
Use high-quality marijuana seeds and plant each seed in its own container.
Always label containers and record every step.
Provide a pH-neutral, high-humidity germination environment, with an ideal temperature between 68-86 (20-30C).
Expect sprouts to emerge between days 3 and 10.
Why Would I Want to Germinate Cannabis Seeds Directly in Soil?
You May Want to Germinate Seeds Directly in Soil if you are:
Can I Just Make a Hole in the Dirt, Drop a Seed, Water it, and Walk Away?
Should I Pre-Soak or Pre-Treat Seeds Before Planting Directly in Soil?
What is the Best Temperature and Humidity for Germinating Seeds?
How Long Does it Take for Cannabis Seeds to Sprout from the Soil?
Why Would I Want to Germinate Cannabis Seeds Directly in Soil?
Known as “direct sowing,” planting marijuana seeds in soil is a good practice for growers of all experience levels.
You May Want to Germinate Seeds Directly in Soil if you are:
Advantages of Germinating Cannabis in Soil Include:
It takes less dexterity. If it’s difficult for the grower to work with small, precise, and gentle motions, germinating in soil removes the risk of damaging delicate new plants during transfer to a substrate.
It can save time. If you are germinating many seeds at once, direct sowing saves the time you’d spend observing and transplanting sprouts.
Plants’ relationships with supportive microbiology (their inherited beneficial bacteria, in particular) are built from the outset of their life journey.
Are There Downsides to Germinating in Soil?
Germinating cannabis in soil is a good choice, but it’s not always the best option.
You May Decide not to Germinate in Soil Because:
You’re planning to grow cannabis using hydroponics
It demands patience and faith in the process; direct sowing can take longer to see results.
Outdoors, direct sowing leaves seeds vulnerable to weather and animals.
Direct sowing in soil requires a bit more trust in the quality of the seeds and your environmental controls. Consistency is key to building this confidence.
The process will take time. Temperature fluctuations, uneven moisture in the soil, inconsistent planting depth, and using seeds of different ages and genetics can mean you’ll see evidence of success (or lack of it) over a period of up to two weeks.
If your schedule won’t allow you to start from scratch two weeks later, it’s better to pre-germinate your seeds either by soaking them in water or with a paper towel. That way, you can catch a glimpse of the emerging root as soon as possible and know whether or not you’re ready to move forward with the seedling phase of cultivation.
The trade-off is that you must monitor germinating seeds more closely when using the temporary paper environment of the paper towel method. In water or paper, you’re essentially “on call” for transplantation. When your seeds are tucked into a comfortable soil bed, you can take more of a “shift work” approach, checking at fewer intervals.
What Do I Need to Germinate Cannabis Successfully in Soil?
Of course, first, you’ll need some high-quality cannabis seeds.
Good and Healthy Loose Soil
For our purposes, “soil” refers to a loose growing medium, like a commercial potting mixture containing ingredients like coir or peat for structure and perlite for moisture management. It’s not (yet) a complex, “living” soil that contains additional organic material and already supports a population of microbes.
Ideally, start with a brand new bag of mix. The manufacturer should guarantee it is free from insect eggs, harmful bacteria, and fungi that lead to fungal diseases. It should also have a proven ratio of components. Ensure you handle and store your potting mixture carefully to avoid contamination.
If you wish, add some microbial inoculants (beneficial bacteria and fungi) designed for use at the sowing stage. These will support germination and early growth. You can make your own, but working with those you can find at your favorite garden supply is easier if you’re new to growing. Follow the application instructions and err on the side of “less is more.”
The Right Container
Make sure these are very clean, with good drainage. Practicing “one container, one seed” prevents young plants’ roots from tangling, which can lead to damage during transplantation.
A leak-proof tray or dish lets you water from below, helping prevent soil compaction. Subdivided reusable trays, individual pressed soil blocks, and compostable mini-pots made from paper are all good options.
If you’re brand new to this whole growing-in-soil thing and need a confidence boost, check out “How do I properly fill a container with soil?” below.
Quality Water
The water you use for germinating seeds needs to be clean and chemical-free. In most areas, household tap water is safe to start with. Distilled water is better if you know you have “hard water” (full of minerals).
Have a spray bottle or other mist-making watering device (a hose with a multi-selection nozzle, e.g.) on hand for post-sowing moisture maintenance.
Humidity Dome or a DIY Humidity Maintenance Setup
This can be anything from a propagation kit to a cloche, transparent plastic bag, or clear food wrap.
Know The Correct pH Levels of Your Water and Soil
At some point, nearly every grower needs to be able to check the pH of their water and substrate to provide plants with favorable conditions. If not using pH-neutral distilled water, check and adjust to 7.
A Thermometer To Check The Environmental Temperature
Choose one capable of displaying accurate and precise measurements, whether probe or laser. It should be easy to read the difference between 68, 75, and 86°F (20, 24, and 30°C). An inexpensive stick-type thermometer, left in one of the pots, works well as a reminder to check the soil temperature regularly.
Stick Tags To Remind You What is What
Label with the Seed Name, type (e.g., “Fem,” “Auto,” “CBD”), and Planting Date. If you don’t use stick tags, you will have to make a new container label for each transplantation or rely on organization and record-keeping. The importance of “doubling up” on labeling and never depending on memory is best not learned through experience.
You may also need:
pH adjusting chemicals, if not using distilled water.
A heating mat, if containers are on a surface that gets colder than 68(20) degrees.
A Step-By-Step Guide on How to Germinate in Soil
Step 1: Assemble Supplies and Tools
Collect the items listed in the section above.
Step 2: Prepare the Soil
At least one day before planting, set filled containers or soil blocks into a tray or dish. Add water from the bottom and allow time for the soil to wick water evenly throughout.
Use your thermometer and stabilize soil between 68-86°F (20-30°C). This range’s higher and lower ends become less friendly for new plants, so aim for 75°F (24°C).
Step 3: Label and Record
Label each container, or clearly mark the space (row or square foot) if you’re planning to grow outdoors on a plot of land. Make a written (or photographic) document that includes the Sowing Date and Seed Name/Type.
Step 4: Make a Hole for Each Seed
Using a clean finger or a sanitized poking tool (e.g., a chopstick or pen), make a hole in the soil about ⅜ of an inch (about 1cm) deep.
For best results, mark this depth on whatever you use as a dibbler (pencil, chopstick, or finger) with a permanent marker or some tape. Now, you can ensure each seed is planted at the same depth. Planting evenly helps seeds progress along the same timeline.
Pro tip: Plant seeds slightly deeper (1/2 inch, 1.25cm) if the soil surface is exposed to bright light. Monitor the effect of light (especially sunlight) on soil temperature and moisture.
Step 5: Sow Your Seeds
Place one seed per hole and fill in with a light cover of soil.
Step 6: How To Plant A Seed
Use tweezers to plant the seeds and make sure to handle them with care.
Step 7: Fill In The Tops Of The Holes
Cover the seeds at the top by adding soil. Do not compact the soil and make sure to match the soil texture above and below the seed.
Step 8: Mist Surface
Gently and evenly mist the top layer of soil with water.
Step 9: Cover to Preserve Humidity
Use a clear covering to provide a high-humidity (70-90%) environment. Ventilate slightly to allow some air exchange.
Step 10: Protect Your Seeds From The Light
It is important to protect cannabis seeds and their new roots from light during germination. Experienced growers commonly wait until seeds emerge before providing light.
You can generally expect some variation in each seed’s time to germinate. Seeds planted deeply enough in the soil will have the protection they need to sprout and can enjoy the light as soon as possible once they have popped up.
Place under seedling-friendly lighting on an 18/6 (on/off) schedule, starting with 6 hours of darkness. LED strips designed for horticulture are best for efficiency, ease of use, and long-term cost savings, but a cool-temperature fluorescent (T5) bulb also does the trick. Providing a day/night differential from the start of life helps the plants develop a rhythm to regulate growth and other cycles.
Step 11: Maintain Conditions and Records
Take note of changing environmental conditions (temperature difference between day and night, for example).
Track each seed, or, minimally, each different variety, to judge both the suitability of your environment and the germination rate.
Pro tip: Germination rate includes the total number of successfully germinated seeds (how many grew vs. how many you planted) and how long it took to emerge.
Common Questions about Germinating in Soil
How do I Properly Fill a Container with Soil?
Set the container to be filled on something to catch spillage (e.g., a tray, tarp, or unfolded newspaper.)
Before opening a bag of purchased potting soil, rotate and shake it to ensure the contents are evenly mixed and well-aerated. Cannabis roots need space to breathe!
Pour the soil from the bag into the containers from about 3-6 inches away so it does not become overly compacted. If you must scoop it from a large bag into your containers, ensure the scoop and your hand/arm are very clean so you don’t contaminate any leftovers. Keep unused soil safely sealed.
Fill divided trays to the surface, and leave 1-2 inches (about 3-5 cm) of empty space in the top of pots.
Steps to accurately fill a container with soil.
What is a Soil Block?
A soil block is a slightly compressed cube of moist soil formed using a mold. They’re often available from garden suppliers; however, growers frequently make them themselves.
Can Seeds Germinate in Soil if Placed Upside Down?
Yes. In fact, “upside down” is a bit of a confusing concept when it comes to planting seeds.
When directly sowing in soil, place the seeds flat on their wider sides. This lets the young plant independently position itself in space with its taproot facing down.
Cannabis has a strong sense of gravity. Sprouts direct their own growth using a principle called “gravitropism,” digging the root tip downward and stretching its first leaves (also known as “seed leaves” or cotyledons) toward the soil surface.
Inside its protective shell, the tiny cannabis embryo is wrapped around itself in a fetal-like position. As the new plant rapidly develops, it uncurls, pushing through the earth and using the friction of emergence to pull its hard casing off.
Even though it might seem logical to direct the pointy end (where the root will pop out) downward, an un-germinated seed planted this way can sometimes grow so straight (the root is already oriented down) that the hard casing stays stuck on its ‘head’ even after it’s reached the surface. This stalls (or stops) the cotyledons from starting photosynthesis, which is necessary for growing your seedling’s first ‘true’ leaves (the ones that look like cannabis).
Visual representation of a seed’s internal structure.
Will Weed Seeds Germinate on Top of Soil?
No. Unlike many flowers, cannabis will not germinate if merely scattered or placed on top of soil. They are sensitive to light exposure and will resist sprouting. If you want to read more about how to germinate seeds the right way, please subscribe to Robert’s Grow Bible below.
Can I Just Make a Hole in the Dirt, Drop a Seed, Water it, and Walk Away?
You could, but as they say, “your results may vary.”
Except on large farms or in some guerrilla grows (when folks sow seeds in public gardens as a form of protest or beautification, for example,) it’s not conventional to simply plant marijuana seeds in the ground and let them fend for themselves through the critical early stages of life. Growers working with autoflowering varietals (a.k.a. “strains” or cultivars) may choose to plant directly into fields, raised beds, large containers, or other prepared and, ideally, protected environments. Autoflower varietals progress so quickly that transplanting them will negatively impact your yield significantly.
Experienced growers often plant more autoflowering seeds at a closer spacing and plan on thinning (removing extras) once they can trust their young plants are established. For example, if you want each adult plant to have 4 square feet of space, you might plant two seeds in that area. If both pop up, you’d remove the less vigorous one while it’s still young. If you’re careful not to disturb the roots very much, you may be able to transplant extras to another pot or section of the garden.
Another good option, rather than close planting, is to stagger sowing dates. If all of the seeds in the first batch emerge in only a few days, you can duplicate your process and expect the whole group to be harvestable within a similarly close window. Don’t forget to keep good records!
Elevated garden beds for cannabis cultivation.
How Much Water Should I Give my Cannabis seeds?
Give enough for the soil to be moist but not soggy. The actual quantity of water depends on how much soil is used. Seeds need to absorb water from their environment to start germinating. The new roots can be stunted if they try to grow into pockets of dry or waterlogged substrate.
Preparing the soil in advance is the best way to avoid excess water and ensure the right amount of available moisture.
Use a known amount of water – for example, 1 Litre – and add it to the tray where your containers with soil are placed. Wait for an hour; when the soil surface is dark with moisture, pour out the leftover water in the tray and measure how much water remains in the tray – for example, 0.6 Litre.
Subtract this number from your initial amount to learn how much water your planting substrate holds – in this example, 0.4 Litre.
The difference between what you started with and what remains is how much water your soil holds (in this example, the soil retained 0.4L). Now you know approximately how much you can expect to need when making up new containers of the same size with the same soil mix to ensure you’re not creating a ‘dead zone’ of super-saturated soil in the bottom.
As your plants grow, the watering technique and amounts will change.
Determining the water requirements for my seeds.
Pro tip: Potting mixes are often acidic before watering. Test the pH of water runoff to confirm the final germination environment is within the ideal range of 6-7.
Should I Water During the Sprouting Process?
No. After you have misted the soil used to cover seeds after sowing, do not water again unless the soil surface dries out.
Using a humidity dome and maintaining a safe temperature range of 68–85 degrees Fahrenheit (20-30 °C), with a sweet spot of 75-76 °F (24-25 °C), is usually enough to keep the soil surface from becoming crusty and stop sprouts from popping up.
Should I Pre-Soak or Pre-Treat Seeds Before Planting Directly in Soil?
There is no need to do anything to recently-acquired, high-quality seeds before planting them straight from the package.
A healthy weed seed
Pro tip: If your seeds have been exposed to surface contamination (e.g., you previously opened a pack and touched some of the seeds, then put them back into storage), you can rinse them with a very mild (0.05%) solution of hydrogen peroxide in distilled water before sowing. If your seeds are relatively old or haven’t been kept in good conditions, or you simply aren’t sure, it is a good idea to scarify and soak them before putting them in soil.
What Type of Soil is Best for Germinating Cannabis Seeds?
The best type of soil to germinate cannabis is a potting mixture specifically made for starting seeds and hosting young plants. Even living soil advocates often suggest germinating seeds in a simple, less biologically diverse environment such as a potting mix. However, If you plan to let plants grow in the same place from germination to harvest, living soil, rich in beneficial microbes and available nutrients, is the best for direct sowing.
Example of a living soil.
Do I Need To Feed Germinating Seeds Additional Nutrients?
No. Seeds contain the building blocks to produce the energy they require for sprouting. Seeds are very sensitive to their growing environment’s chemical and physical makeup during germination. Keep it simple!
Does the Soil Need a Certain PH when Germinating?
Yes. Aim for a neutral or slightly acidic germination environment (6-7). Substrate pH is affected by its composition, including the water you’re using.
What is the Best Temperature and Humidity for Germinating Seeds?
The best temperature range for cannabis germination is 68-86°F (20-30°C). The ideal soil temperature is about 75°F (24°C). Humidity is best kept between 70-90%.
Do Cannabis Seeds Need Light for Germination?
Cannabis seeds do not need light to germinate. In fact, root exposure to light during sprouting can slow or stop the new plant’s development. Planting your seed on the deeper side when directly sowing in soil is better.
How Long Does it Take for Cannabis Seeds to Sprout from the Soil?
In general, around three days is a quick germination period when direct sowing in soil.
Remember, seeds are living organisms—factors including genetics, seed maturity at harvest, storage duration, and conditions matter. The provided germination environment also impacts how long it will take for you to see sprouts. Follow the steps above, be patient, and you should soon have some healthy little plants on your hands!
A young cannabis seedling in a tray.
How Long is Too Long?
Ten days or less is a standard amount of time to wait for marijuana seeds to germinate and emerge from the soil. Don’t even think about digging around to see what’s happening with your seeds during this time!
After two weeks, most people will consider the seeds to be dormant (still alive but resisting germination) or non-viable. They may also have begun germinating and encountered a condition (e.g., a fungal disease like “damp off,” too-dry or too-wet substrate, or unfavorable temperature) that they could not survive.
However, if you are dealing with stubborn seeds, there are options such as treating them with H202 or scarifying the seeds before you sow.
Is It Better to Germinate Seeds in Soil or Paper Towels?
Whether it is better to germinate in a damp paper towel or sow directly into soil depends on both the cultivator and the seeds.
If you have any doubts about the germination vigor of your seeds (e.g., they have been stored at less-than-ideal conditions, are old, or possibly dormant), it is better to try germinating in paper towels. This lets you see if the seeds are going to sprout within a matter of hours (usually within 72). Once you observe the signs of germination, you can transfer the seeds to the chosen substrate.
If you are germinating many seeds (let’s say, a divided flat tray of 50 to 72 cells or an outdoor plot where you will over-plant and thin later), can tolerate waiting longer to see results, or have a concern about your ability to transfer delicate sprouts without causing damage, direct sowing in soil is a better option.
Growing cannabis in natural forest environments.
Is Germinating in Soil the Best Method to Germinate?
Germinating in soil is the best method for growers who have:
Dependable seeds
The intention of growing in living soil
Experience growing in soil from seed and/or
Difficulty with small, delicate movements
If you have plenty of seeds, a tolerance for the unpredictable, and familiarity with the specific soil and location you’re working in, you can sow cannabis like other summer annuals.
Pro tip: Be sure your chosen variety is suited to local climatic conditions (temperatures, available sunlight, and season length). It’s a pleasure to see robust young cannabis seedlings establish themselves in the most natural setting available and survive to flower to their full potential.
Final Thoughts
Successfully germinating in soil connects you to the journey your cannabis seed would take if it were wild and free. Knowing the world can be dangerous for a young plant, practice a form of land stewardship on this small scale. Offer protection guidance and introduce friendly companions to help it thrive.
Until next time, may you and your garden grow together ever higher!
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