Do weed seeds need sunlight to germinate

How to Germinate Cannabis Seeds

Germination is the beginning of your cannabis seeds’ life and is easy to master. At this crucial stage, seeds grow and sprout into young seedlings. The best genetics deserve the best start, and all you need is two plates, some paper towel, and water. Apply the best germination method today and enjoy a great harvest.

1. Germination set-up

Prepare the first plate by lining the inside surface with two to three layers of damp paper towel. Drain excess water from your plate.

Place cannabis seeds on the top surface of the damp paper towel. Approximately three per plate; ensure they are not touching but are evenly spaced apart.

Add only a few layers of damp paper towel on top of the seeds, and let any excess water drain from the plate. Too much water lowers the chance of successful germination.

To complete the set-up, place the remaining plate upside-down and on top of the first plate, resembling pearls inside a clam.

2. Germination

Cannabis seeds need a dark, warm, and humid atmosphere to germinate.

Around 21°C (70°F) is perfect. Check the paper towels every second day and if required, spray with water to keep conditions moist for your seeds.

After a few days, tiny roots will begin to emerge. Congratulations! Your seeds have survived their first stage of life. Don’t worry if some of your seeds have not yet changed, they may just need a little more time as germination can take up to 14 days.

3. Plant of the seeling

Once the roots are a few millimetres long, they are ready to be delicately transferred to a small container filled with your growing medium of choice (rockwool, coco-fibre, or soil).

Make a hole in the growing medium that is 2 – 5 mm deep. Use tweezers or your fingers to transfer germinated seeds gently into the hole (root pointing down) and lightly cover with a fine layer of your medium. Do not pat it down too hard. The stem and the first tiny set of leaves, called cotyledons or ‘seed leaves’, should begin to emerge 24 to 72 hours after the seeds are planted.

4. Supplying a light source

Seedlings must be exposed to sunlight once they sprout. Ensure this is a gradual process as too much heat causes stress and will stunt growth.

Find a sunny place where you can begin to increase sun exposure, such as a windowsill. Ensure sun exposure is increased by an hour or so a day.

For an indoor plant you can use a fluorescent light (keep normal distance from bulb) or HID lighting (50-80 cm from the bulb).

Take care in the first week or two, as seedlings are still quite delicate and sensitive to the elements. They won’t need a lot of attention until the vegetative stage so avoid overhandling.

Germination is the beginning stage of the growing cycle, and this easy-to-follow guide gives your premium genetic cannabis seeds the best start to life. Whether you are a first-time home grower or a well-seasoned gardener, share your experience or any questions in the comments down below, as well as your tips and tricks!

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Laws and regulations regarding cannabis cultivation differ from country to country. Sensi Seeds therefore strongly advises you to check your local laws and regulations. Do not act in conflict with the law.

Comments

22 thoughts on “How to Germinate Cannabis Seeds”

Hi, Once seeds have sprouted, how long can or should you leave them to grow under 24 hr lights before moving to your outdoor garden?

Good afternoon Ken,

I hope you’re having a great day.
For the vegetation process, a light schedule of 18 hours of light, and 6 hours of darkness is preferred. Many growers get plants acclimatized to outside by placing them in a window, or under direct sunlight for a few hours a day.

Thanks again, and have a great day!

Hello everyone, all these suggestions are wonderful but I think a lot of you make it sound a little overwhelmingly. I’ve been very successfully cultivating for decades and I’ve always just placed my seeds, be it 1 or 100, in between 2 folded sheets of tissue which I’ve made wet with tap water. I then place them on a tray or plate in a warm dark area , such as an airing cupboard and leave for how ever long they take usually, 12 to 24 hours. The ONLY thing I do which takes effort is PH balance the water I germinate them in and I’ve only lost 5 seeds in nearly 40 years .

Good afternoon Paul,

I hope you’re having a good day,
Thanks for sharing your experiences with germination. pH balancing is a great tip You also might be interested in our new Jamaican Pearl Feminized Grow Report

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Thanks again, and I hope you continue to enjoy the blog,

I lightly score my seeds by shaking them inside a rolled up piece of sandpaper – sandpaper side on the inside before leaving them in a cup of water for a few hours to hydrate. I then place them between wet (good quality) paper towel per instructions above. I find using an old plastic takeaway container with a heatmat below keeps the humidity high and with good end results.

Good morning Jonny,

Thanks for sharing your methods for germination with us, the heat mat and low-humidity are great tips!

Thanks again, and I hope you continue to enjoy the blog,

I have found out that the best and fastest way is to take a glass of clean/filtered water and place the seed right on top of the water (floating – NOT immersed in it!). If the seed is viable it will sprout in no more than 48 hours. Right after that you plant it in your pot/soil etc and you’re done.

Good morning Mary Jane,

Thanks for your support, and for sharing your experiences with germination!
You might also be interested in our article on The Life cycle of Cannabis: From seed to harvest.

Have a great day!

What happend if they sink I had em sink they came out fine

Are you saying they sprout in the glass of water and don’t “drown”?

Take aluminum foil flatten it out and put on top of your dirt it detects planes and grow it just like a tomato plant

Good morning Tammy,

Thanks for getting in touch with Sensi Seeds, and sharing your germination method with us!

Thanks again, and I hope you continue to enjoy the blog.
With best wishes,

Detects planes? Like magnetic? I’ve always has best success 24-48 hours soaked In water, spring water if possible. Usually do this in a shot glass, once they pop I’ll take a paper towel fold so it’s 2 layers then fold once more so you know where center is. Dump the seed in the middle of the edge and the true center (reason we folded a 2nd time)as well as the water just enough to saturate the paper towel. Do not soak! Carefully with the seed in the middle using sterile tweezers turn so the tap is growing down. This will prevent circling and tangling if doing multiple seeds. Now you can fold the other half so your seed will be “sandwiched” between 2 layers. At this time carefully take a corner and the waters attraction should keep your paper towel from unfolding but just in case be gentle. Holding it from 1 corner you can dangle it over a cub or the original shot glass so any extra water runs off. Now take a standard zip or press n seal sandwhich bag and slide your napkin in Carefully . REMEMBER which way was down! Work the air out making jt flat snd seal. Find a temperate dark area around 70°. A cabinet works we’ll as your going to prop it up with taproot facing downwards. Now just close it up and wait in 24-72 hours checking once a day. In rare cases you could have a 1/2″ tap root in the first 24 hrs some may take 4-5 days. Once the tap is about 1/2″-3/4″ long its ready for transplant into its first small pot. With this paper towel method I typically have 100% success.

Can you leave your seed to develop longer roots in the germination phase and can this make them better to grow or is a big no no?
Last year, I had 2 seeds that had really long roots with lots of secondary roots coming out when they were planted, one of which died after a couple of weeks and the other grew into a huge plant.
The other two seeds only had a short germinated growth and both died almost immediately after planting so not sure what I can learn from this…lol

Appreciate any thoughts and advice

Unfortunately, legal restrictions mean we can’t answer grow-related questions or give grow advice on this blog. However, other readers of this blog will often answer questions like yours.

Please check out the following articles on our blog which I think you may find of use, and I hope you continue to enjoy the blog!

With best wishes,

How often do you water and how wet should the plant be? Please.
Also if they are outdoor plants do you need to keep them covered with clingfilm for a wee while or do you just hope for the best. Thanks

This article, about how to water cannabis plants, should answer your questions. I can’t help you with the clingfilm one though, as it depends on the climate. Good luck, and happy gardening!

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With best wishes,

Just drop the seeds in water, they will sprout , don’t have to use a towel and check it all the time , drop it in the water , let it float then it will sink and the root will grow out ,let the root get 1/4 inch and plant it where it’s going to grow , 8 hours sunlight starting as soon as it is out of the soil. Always grows great , don’t have to transplant from cup to gallon to bigger and bigger , if it’s growing outside put it where it stays , always does just fine.

Good afternoon Graham,

Thank you so much for sharing your experiences with germination.

Thanks again for your comment, and I hope you continue to enjoy the blog.

Have a great day!

I recommend this article to all breeders and cultivators who plans to germinate seeds and to some who don’t know how to germinate seeds, this article has the best and perfect ways on how to do it.

I have large bay windows at my condo which get about 11-12 hours of light per day. They are tinted but warm. I grow other indoor plants there perfectly. Is an ok place for my pot plants?

This sounds like a great place for all kinds of plants! I recommend you have a look at autoflowering varieties, as otherwise light pollution may negatively affect the flowering cycle. Good luck, and happy gardening!

With best wishes,

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Top 5 Germination Mistakes To Avoid When Growing Weed

Germinating cannabis seeds is necessary in order to sprout seedlings that develop into mature, healthy cannabis plants. However, complications with light, humidity, heat, and more could result in cannabis seeds failing to sprout. Find out what to avoid to ensure successful germination.

Germination is where the magic begins. Cannabis seeds must first germinate in order to sprout and begin their journey as living, breathing plants. However, if the germination process is done incorrectly, or is thwarted by some other variable, seeds can fail to sprout, leaving you with useless, spent seeds instead. Here are the top five mistakes to avoid when germinating cannabis seeds.

GERMINATING BAD SEEDS

One of the most common reasons seeds fail to germinate is because they are simply duds. Typically, healthy cannabis seeds should look a specific way and be of a specific colour. Viable seeds will appear round, not flat, and should be a beige to dark brown colour with subtle tiger striping. Seeds that have been flattened or are pale in colour may have a tough time sprouting into healthy cannabis plants.

Seeds that have been improperly stored may also fail to germinate. These tiny packages of DNA prefer to be kept in a cool, dark place with moderate humidity. Exposing them to heat, light, or extreme humidity levels (both high and low) could result in seeds losing their viability. As long as you source your seeds from reputable seedbanks and store them appropriately, you shouldn’t have to worry about bad seeds ruining your chances of successful germination.

TOO MUCH LIGHT

Generally speaking, seeds require a dark environment in order to germinate. After all, in nature cannabis seeds find their home in the dark embrace of soil. It can be hard to determine exactly how much light is too much for your seeds; however, err on the side of caution and germinate out of direct light. There’s no need to use your grow lights until after germination has occurred.

It is also likely that the quality of your seeds will affect their ability to handle direct light. Seeds that are already having a tough time germinating will have an even worse time doing so if they are exposed to excess light.

TOO MUCH OR NOT ENOUGH WATER

The amount of water you supply your seeds during the germination process will also affect their ability to successfully germinate. Some growers attempt to germinate by “drowning” them in a glass of water. While this ensures they will not go thirsty, it can actually be more harmful than helpful.

Once they pop, seedlings are very delicate and must be watered carefully. When germinating, your medium should be damp, but not overly wet for best results. On the other hand, a dry environment is basically a death sentence for your seeds. They need a constant source of moisture to sprout, otherwise they’re good as duds.

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TEMPERATURE PROBLEMS

Cannabis seeds require a specific temperature range in order to germinate. Regardless of the germination medium you are using (soil, paper towels, etc.), the temperature in the environment should consistently sit in the 26–28℃ range. Seeds need to be kept warm during the germination process. At no point during germination should seeds be exposed to temperatures below 20℃.

There are some techniques that can be used to ensure your seedlings remain in this temperature range. Some growers choose to use special warming mats that can be set to a specific temperature and placed underneath the seedling containers. Another strategy is to place a timed heater close to your seedlings to warm them up occasionally. Once your seeds have sprouted, they will be much more resilient to fluctuations in temperature.

GERMINATING IN SOIL

Many people choose to germinate their seeds using paper towels. However, others choose to do so directly in soil. Of course, germinating your seeds in soil isn’t inherently bad, but it can come with its own set of challenges, and is generally not recommended unless necessary.

For instance, the upper layer of soil can dry out within 48 hours, making it more difficult to give your seeds the right amount of water they need without overdoing it. Giving your soil too much water during germination could result in the seed rising up or dropping down further, inhibiting its viability. Moreover, seeds that are planted too deep in the soil could experience a host of complications. They could suffocate before coming into contact with enough oxygen, and be unable to access sufficient light to progress into the seedling stage of their life cycle.

Seeds may also be unable to germinate if the soil they are planted in contains contaminants. Mould and pests can easily kill a mature, healthy weed plant within just a matter of weeks. It should come as no surprise then that they could also prevent a small seed from germinating. If your soil contains traces of these contaminants, it is possible that your seed will never actually open and sprout. This also applies to fertilisers. Even small amounts of fertiliser in your soil can effectively kill your seed, making it completely useless.

When can seedlings be put under lights or in the sun?

Not sure whether to grow your cannabis seeds in the sun or under lights? This article explains how much light you need, how to prevent your seedlings from falling over, and when to plant them outside.

“When can cannabis seedlings be put under lights or in the sun?” is a common and sensible question that is often asked by novice cannabis enthusiasts after germinating seeds indoors under lights.

For those who are growing indoors, cannabis seedlings may be put under lights as soon as they emerge from the soil or growing medium.

How much light for cannabis seedlings?

When using HID lighting (usually a metal halide lamp), young seedlings should be kept at least 50cm from the bulb.

With compact fluorescent lamps (usually 100w or more), a distance of around 15cm should be maintained between the top of the young seedlings and the bulb.

If using normal fluorescent tubes (18-36w), seedlings can be kept within a few centimetres of the light source.

Cannabis seedlings growing under lights should always be given a gentle breeze from an oscillating fan (a small household fan on the lowest setting is fine), as constant gentle movement will strengthen their stems significantly.

Are your cannabis seedlings falling over?

If cannabis seedlings grow tall and then fall over, this is almost always a result of growing in an environment with static air.

Seedlings intended for outdoor growing should be kept by a sunny window for the first week or two after emerging from the soil.

When they have grown their second or third set of serrated leaves (after the the round cotyledons that initially emerge from the seed) seedlings are usually hardy enough to flourish in direct sunlight.

When to plant your cannabis seedlings outside?

If outdoor temperatures are suitable, seedlings may be acclimatised to direct sunlight by giving them progressively longer daily exposure to outdoor conditions.

Starting with about three hours outside, at the sunniest time of day, seedlings can be given an extra hour of outside exposure each day, so that within about two weeks they can be left outdoors permanently.

Laws and regulations regarding cannabis cultivation differ from country to country. Sensi Seeds therefore strongly advises you to check your local laws and regulations. Do not act in conflict with the law.