Cannabis sativa sp. is commonly known as marijuana and has been grown throughout the world for thousands of years. Cannabis seeds germinate in 3 to 7 days, though some varieties may take 10 to 15 days. While germination is a natural… Jorge Cervantes, veteran marijuana cultivator and author of “The Cannabis Encyclopedia” shares his process for germinating cannabis seeds into healthy sprouts. Learning how to germinate cannabis seeds is the first step to growing marijuana, but it's not as easy as many aspiring cultivators think.
How to Germinate Cannabis Seeds
This article was co-authored by Lauren Kurtz. Lauren Kurtz is a Naturalist and Horticultural Specialist. Lauren has worked for Aurora, Colorado managing the Water-Wise Garden at Aurora Municipal Center for the Water Conservation Department. She earned a BA in Environmental and Sustainability Studies from Western Michigan University in 2014.
There are 10 references cited in this article, which can be found at the bottom of the page.
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Cannabis sativa sp. is commonly known as marijuana and has been grown throughout the world for thousands of years. Cannabis seeds germinate in 3 to 7 days, though some varieties may take 10 to 15 days. While germination is a natural process, factors such as light, humidity/moisture, and temperature must be controlled for cannabis seeds to sprout.
How to Grow Weed: Germinating Cannabis Seeds
Jorge Cervantes shares his process for germinating cannabis seeds into healthy sprouts.
The gardening season is booming in North America, and it’s high time to start some tiny seeds that can grow into potent plants, says Jorge Cervantes, veteran marijuana cultivator and author of “The Cannabis Encyclopedia”.
1) Soak seeds overnight in a glass of plain water. They may float on the surface at first but should sink to the bottom in a few minutes. Make sure seeds get good and wet so that water penetrates the outer shell and growth is activated. Do not let seeds soak for more than 24 hours, or they might get too wet, suffer oxygen deprivation and subsequently rot.
2) Remove seeds from the water. Pour water out onto two paper (or cloth) towels on a dinner plate. Fold the towels over the seeds to cover them.
3) Drain the water from the dinner plate by tipping it to the side.
4) Place the seeds in a warm location (70°F–80°F; 21°C–27°C), making sure they are in darkness. Some gardeners go so far as to set the plate in a vertical position (so taproot grows downward). The seeds can also be set on a grate for drainage and air circulation.
5) Check moisture level of towels several times a day, watering once or twice to keep them evenly moist. DO NOT LET THE TOWELS DRY OUT! Let excess water drain away freely. The paper or cloth towels will retain enough moisture to germinate the seeds in a few days. Each seed contains an adequate food supply for germination. Prevent fungal attacks by watering with a mild 2 percent bleach or organic fungicide solution.
6) In a few days, seeds will sprout. Once the germinating cannabis seeds have sprouted and each seed’s white rootlet is visible, use tweezers to carefully pick up the fragile, germinated seeds and plant them. Do not wait for the white rootlets to grow more than 0.25 inches (1 cm) before planting, or growth could slow. Plant each germinated seed with the white root tip pointing downward. Take care not to expose the tender rootlet to prolonged light and air. Cover germinated seeds with 0.25 to 0.5 inches (1-2 cm) of fine, moist planting medium.
Other Tips for Germinating Cannabis Seeds
Over and under-watering are the biggest obstacles most gardeners face when germinating seeds and growing seedlings. Keep the soil uniformly moist but not waterlogged. Do not let the growing medium’s surface dry for long. Setting root cubes or planting flats on a grate allows good drainage.
A shallow flat or planter with a heat pad underneath may require daily watering, while a deep, 1-gallon (3.8 liter) pot will need watering every three days or more. A properly watered flat of rockwool cubes needs water every three to five days when sprouting seeds.
When the growing medium’s surface is dry (0.25 inches [1 cm] deep), it is time to water. Remember, there are few roots to absorb the water early in life and they are very delicate.
Some seeds have a very hard outer shell (testa) and are difficult to germinate. Such testy cases can be softened or scarified to allow water to penetrate. To scarify, line a matchbox with a piece of fine-grain sandpaper or emery board. Put the seeds in the matchbox and shake for 10 to 15 seconds. Remove the seeds and make sure they have been scuffed a bit. Just a little scuffing will allow water to enter and set germination in motion.
1) Set seeds in a matchbox with an emery board or sandpaper on the bottom.
2) Close seeds inside the matchbox.
3) Shake matchbox for 10 to 15 seconds to scarify the seeds.
This is an excerpt from “The Cannabis Encyclopedia” by Jorge Cervantes, world-renowned indoor, outdoor and greenhouse cannabis cultivator. A veteran marijuana grower, Cervantes brings 30 years of experience traveling, studying and writing to bear in his best work to date.
How To Germinate Cannabis Seeds
Cultivating cannabis from a seed is not as easy as many beginner growers might think. Various factors are involved which will ultimately determine if the cultivator is successful and has a large harvest, or if they fail and have to go back to the drawing board. Learning how to germinate cannabis seeds is the first step to becoming a cultivator.
Some cannabis cultivators prefer to start with cannabis clones versus marijuana seeds. Each route has its own advantages, however, seeds are typically easier to acquire than clones. While clones and seeds will both do the trick, seeds also seem to be a more popular route in many areas.
It’s worth noting that purchasing cannabis seeds online is illegal and often results in less than desirable seeds being acquired by the buyer. Look for legal cannabis seed options in your area. Many reputable licensed cannabis dispensaries sell cannabis seeds, with strain options varying.
How Do You Know If A Cannabis Seed Is Viable?
If you consume cannabis long enough, chances are you will come across a seed in your cannabis flower. Whether you want to try to germinate the seed immediately, or save it for down the road, it is important that you know if the cannabis seed is viable to be germinated or not.
Viable cannabis seeds tend to have a darker color with shades of grey, black, and/or brown. A really good cannabis seed will typically have a ‘tiger stripe’ across it. Another way to tell if a cannabis seed is viable is by touching it (make sure to wear gloves when handling cannabis seeds). A quality seed should withstand a bit of a pinch. If the seed collapses under a little pressure, then it wasn’t viable.
How Do You Germinate Cannabis Seeds?
Germinating marijuana seeds is not difficult, although it does take attention to detail and the right environment. Successful germination takes the right amount of moisture, the right temperature, and a decent amount of light (sunlight or artificial light from low-intensity grow lights).
Arguably the easiest and most cost-effective way to germinate a cannabis seed is to place it between wet paper towels (often referred to as “the paper towel germination method”). Add a bit of water to the paper towels and squeeze out the excess water.
You want the paper towels to be moist but not dripping water. Place the seed(s) between the moist paper towels, place the paper towels in a sandwich bag to lock in the moisture, and put it on a window ledge where it will get some but not too much light. Keep the paper towels moist until the germinated cannabis seeds are ready to transplant.
If the temperature of the room is too cold (below 55 degrees Fahrenheit), consider using a heating mat, which can be found at most department stores in the gardening section. The success rate of the paper towel method is high as long as the cultivator keeps a close eye on the process until the germinated seed is ready to be transplanted into potting soil, peat pellets, or a different growing medium.
Various products such as “rapid rooters” can be incorporated into germination strategies, however, they are not as cost-effective as the paper towel method.
When Is The Seed Ready To Be Transplanted?
Watching a cannabis seed germinate can be a lot like waiting for water to boil — it takes time (typically a couple of weeks). The seeds will eventually crack open and a white root will shoot out of the cracked cannabis seed shell. The white root is often referred to as the taproot. Once your sprouting seed has a strong taproot (an inch or so) it is ready to be transplanted.
Find a two-inch container for your grow space, fill it full of soil (or your preferred growing medium), and poke a hole where the seed will be placed. Using tweezers, place the seed with the taproot facing down in the hole. Then, cover it with soil.
From there, you can grow the cannabis seed into a large cannabis plant. One downfall to cultivating cannabis from seed is that you won’t know if the marijuana plants are male or female for several weeks. If the young plant proves to be male, then it is basically useless. Using feminized cannabis seeds is a good way to ensure that the plants are not males, saving you quite a bit of time and headache.
Continuing Your Education
Cultivating cannabis is a never-ending educational journey. Even the most experienced cannabis cultivators will be quick to tell you that they are always learning and seeking out cultivation information.
A great way to learn more about the cannabis cultivation process from seed to harvest is via Green Flower’s Cannabis Cultivation Certificate Program. The program is led by true cultivation experts and involves insightful course materials. If you are looking to increase your cultivation knowledge this is a great way to do it!