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How To Germinate Cannabis Seeds
Cannabis seed germination needn't be a stressful affair. Consult this guide to familiarise yourself with the different germination methods available, so you can see which one is best for you. Plus, learn how to get old cannabis seeds to sprout and grow into healthy specimens.
There are several ways you can germinate cannabis seeds. Some of these methods, however, are a bit risky, so we recommend going an alternative route. In this guide, we’ll discuss our favourite way to germinate seeds, before exploring some of the less-reliable methods. We’ll also review the process of transplanting freshly germinated seeds.
Our recommendation: germinating cannabis seeds directly in the medium
For some reason, cannabis cultivators tend to make seed germination unnecessarily complicated, and also somewhat risky. Maybe you’ve already heard about germinating seeds with moist paper towels or by tossing them in a glass of water—we will cover these methods below; however, we believe the easiest and best way to go about getting your seeds to sprout is to germinate them directly in the growing medium.
Simply put the seed about 0,5cm deep into the soil and cover the seed lightly. Keep an eye on the environment and keep it warm and humid - 20°C is the ideal temperature. Keep soil moist, but don't saturate it - waterlogged soil can do more harm than good. You can place a lamp above the seed to provide the adequate temperature for germination. Your precious cannabis seed will happily sprout within a few days!
Take note that your seeds do not need any nutrients, at least for the first two weeks of growth. New growers often make the mistake thinking they are helping by adding nutrients in this early phase of growth. DON'T! The seed contains everything it needs to grow for a couple of weeks. Adding additional feed runs the risk of burning the seedling out before it has had the chance to even begin growing. Feeding your seedling with plain water ensures that it will grow strong roots. If you really want, you can use a root stimulator although it isn’t absolutely required.
We’ve found that germinating directly in the medium isn’t just the easiest and most reliable way; it’s also the safest method for your seeds. Other techniques require transferring your recently sprouted seeds to a pot, so there’s a risk that the sensitive taproots can get damaged in transition. Other methods run the risk of seed rot. What’s more, we haven’t really found any advantages to using these methods over germinating seeds directly in the medium.
Use germination kits to give your seeds a head start
To make it even easier to germinate your seeds, we recommend using a germination kit like the Zamnesia Smart Start or the Plagron Seedbox. These kits come with everything you need to give your seeds the best start possible.
The Smart Start by Zamnesia comes with 20 tiny pots already filled with compost. Even better, the Smart Start includes a special Stimulator Mix that will benefit germination by activating the microbiological life in your soil. All you need to do is moisten the Smart Start pots with water where you have dissolved the Stimulator Mix, then place a seed into each pot and cover with soil. Place the tray in a location at room temperature, and make sure the soil stays moist (don’t overwater). Your seeds will germinate in a few days. It’s recommended to use the Smart Start kit alongside a propagator to create the ideal environment for seedlings to develop.
Smart Start
The Plagron Seedbox Germination Kit consists of a tray of 12 germination pellets and a snug-fitting transparent lid. It’s like a miniature greenhouse, so it’s the perfect environment for your seeds to sprout! The Plagron Seedbox also includes a bottle of Plagron Seedbooster, so you can give your cannabis plants-to-be a great head start. Moisten the tray of germination pellets with water and the Seedbooster; wait about five minutes for the water to absorb. Put your seeds in the holes, and fit the lid on the tray. Place the tray in a room at 20–24°C, and your seeds will sprout in 1–5 days.
Other, less reliable methods
Aside from germinating your cannabis seeds right in your growing medium, there are other, less reliable methods.
Paper towel method
Our first on the list of not-so-reliable germination methods is the popular “paper towel method”. This involves placing your seeds between sheets of moist paper towel. You then cover the towel and seeds with two plates (or another suitable container like a lunchbox) to prevent undue light exposure, and store it in a warm and dark place. Check on the towels occasionally; if they’ve become dry, give them a little spritz with water. Your seeds should germinate in a few days.
Why we don’t recommend this method: It requires you to excessively handle your germinated seeds as you move them from the towels to their first growing container. For the sensitive taproots, this is anything but optimal. Issues can easily arise (like the roots sticking to the paper), which can easily damage your seeds. Furthermore, the paper can also get too wet, causing your seeds to suffocate or rot.
Glass of water
Another popular germination method is to plop your seeds in a glass of water. This one seems easy, as you just drop your beans in and wait for taproots to appear.
Like the paper towel method, the main issue with the glass of water approach is that it’s just unnecessary. Between the excessive exposure to water and the handling involved in transplanting, you once again put your seeds at risk of suffocating or becoming damaged. That said, some growers use this method to get a quicker visual on whether their seeds are viable. If you are sure of the quality of your seeds, and have sourced them from a reputable seedbank, you shouldn’t need to go this route.
Rockwool
Germinating in rockwool is, in principle, a good way to get your seeds started, although it is more involved than other methods. You place your seeds in a rockwool cube, then put the moistened cubes in a tray or propagator while you wait for your seeds to sprout.
We do like that, unlike other methods, the rockwool protects the young seedlings so you can transplant them safely to larger pots. On the other hand, rockwool requires being soaked in water with a low pH before seeds can be added. Furthermore, rockwool cubes can dry out very fast, which is why we suggest this method for experienced cultivators only.
Peat moss (peat pellets)
Germinating in peat moss pellets (Jiffy Pots) is actually a pretty decent way to get your seeds started. These pellets have the shape of a large pill; moisten them, and the pellets will grow into a larger shape held together by dissoluble netting. Poke a hole into the peat on top and place your seeds into them.
After our preferred method of directly germinating in your medium, peat pellets would be our next-best choice for germination.
What we do not like about peat pellets: The netting around the pellets isn’t always guaranteed to dissolve when you transfer them to a bigger pot. If this happens, the net can trap the roots of your plants so they can’t expand. Because of that, it is recommended that you remove the netting before transplanting, but doing so could possibly damage the sensitive roots of your seedling.
Coffee filter
Germinating with coffee filters is essentially the same as the paper towel method. You place your seeds between two or more sheets of coffee filters, moisten the sheets, then place them in a bag or container that you seal up.
Like the paper towel method, we don’t really recommend this needlessly complicated way of germinating your seeds. The risk of rot or damaging your seeds with tweezers when transplanting just isn’t worth it.
How to germinate old cannabis seeds
There is nothing more frustrating than trying to germinate your cannabis seeds to only find that they have grown too old. Fortunately, all is not lost and it is not necessarily the end for your seeds. Using the following techniques, the great majority of old seeds can be salvaged.
The problem with old seeds is not that they have become old per se, but that their ability to absorb water through their shell has diminished as they have hardened with age – also making it very hard for them to split open. In order to overcome the problem of old seeds not germinating, you need to overcome the problem of poor absorption – there is still life in them seeds! The process we are about to explain is called scarification.
Scarifying your seeds
As the name suggests, scarifying is the process of wearing away the shell, so the first thing you need to is scuff your seeds. To do this line a small matchbox with sandpaper. Put your seed(s) in it, and shake it around for 30 – 60 seconds. This will cause micro-abrasions on the shell surface, making it much easier for it to absorb water.
Hopefully, this will be all you need to do in terms of scarification, but if worst comes to worst, there are two more steps you can take. The first of these two steps is to remove the seed’s ridge. Look at the edges of your cannabis seed. Notice how the seam holding the shell together goes all the way around, but one side is more pronounced than the other. This pronounced ridge can make it much harder for the seed to open up, but can be easily removed:
Take your seed between your thumb and forefinger, and with a sharp knife, very gently run it along the ridge at a 90-degree angle. The ridge should come away, exposing the seed beneath. Carefully turn the seed around, and dislodge the ridge at the other end of the seed so it fully falls off. Now that this is done, you should be able to germinate your seeds as normal.
If they are still not germinating, they are probably done for, but as a last resort, you can run a scalpel down the one side of the seed to open it up a little. This will make it much, much easier for water to be absorbed, but also exposes it to a great deal of potential damage. It is a last-ditch attempt to salvage a seed that would otherwise be thrown away – you should never do this normally.
It is also worth noting that these scarification techniques are a bit tricky to do correctly, and should not be attempted unless you are certain the seeds won’t germinate. Any healthy, viable seed should happily germinate without the need to resort to any of these measures.
Germinating your scarred and scuffed seeds
With the seeds prepared, you can move on to the germination. There are a few ways to germinate old cannabis seeds, all of which are effective in their own right. Before we get into this though, there is one optional thing you can do to boost germination chances, and this is through the preparation of your water.
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Water prep (optional)
There are two ways you can enhance your water for the germination of old seeds. Firstly, you can use lightly carbonated water. The CO2 in the water will help it to be absorbed by your tough, scarified seeds. Secondly, you can also add a bit of fulvic acid into your water, at around 10ml per litre of water. Fulvic acid helps plants with absorption and can lead to healthy growth. Alternatively, you can try using a seed germination booster liquid, which is basically a mix of nutrients ideal for germinating seeds. Although the main obstacle with old seeds is getting the water into them, a few well-balanced nutrients can’t hurt to get them going.
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Soil germination
Our favorite method - soil germination - harnesses the power of Mother Nature and starts the seed's life off just as She intended.
Firstly, place your seeds in a bowl of room temperature water. Place a bit of cardboard over the bowl, and put it into a dark cupboard overnight (12 hours). Once this is done, fill a small pot for each seed with soil – germination soil is best, as it has the right level of nutrients to get your little beauties going. Dampen the soil with water and then create a small, circular indent in the centre. This indent should be 3-5mm deep. Place each seed in an indent, pointed tip down, and then carefully cover them over with soil. Put the pots in a dark, warm room for 6 hours, and then put them under your lights and leave them on. You should see a shoot forming within a couple of days.
Note: Soaking your seed for 12 hours is only usually done with old, tough seeds. You can skip this step for most normal seeds.
Transplanting germinated cannabis seeds
If you start your seeds with our recommended germination method (directly in the medium), you will eventually need to transplant your seedlings.
This promotes healthy plant growth, makes watering and feeding easier, and will benefit your yield. If a seedling is too leggy and fragile to transplant as is, you can cover more of it up with soil to stabilise and strengthen it in its new pot.
You can find out more about transplanting your seedlings by checking out our blog When And How To Transplant Cannabis Plants For Bigger Yields.
Now that you know how to germinate, you can move on to the full seedling phase and beyond!
