How to Germinate Marijuana Seeds Method 1: Starter Cubes & Seedling Plugs (Recommended)
One of the best cannabis germination methods is to use specifically-made starter cubes and seedling plugs. These plugs make cannabis germination easy. You simply place the seed in the cube or plug, add water as directed, and seedlings automatically get the perfect conditions for germination.
Each cube or plug already has a hole specifically for you to place your seed. Just stick your seed into the precut hole and pinch the top closed a bit with your fingers. Don’t worry, you can’t mess this part up 🙂 As long as the seed makes it in there, you should be good.
This is one of the easiest germination methods, and doesn’t leave a lot of room for error. Cannabis seeds and clones can be expensive, and sometimes we have genetics we just can’t afford to lose. When that’s the case, germinate your cannabis with one of the following recommended options to ensure as close to 100% germination rate as possible.
Which Starter Cubes Work Best for Germinating Cannabis?
Rapid Rooters (Highly Recommended For All Setups)
Rapid Rooters are easy to work with – you just stick your cannabis seed in the Rapid Rooter (pointy side down), keep your seed warm and slightly moist, and let the Rapid Rooter do its magic.
Sprouts emerge and roots appear in just a few days.
Rapid rooter starter cubes are suitable for all growing methods, including hydroponics, coco coir and soil. They work for every setup and come from General Hydroponics, a trusted company (the same one used by NASA) which is known for the quality and consistency of its products.
I highly recommend using Rapid Rooters over any other starter plugs. They are less prone to problems and work great with any growing medium (including hydroponic systems).
Pros of Rapid Rooters
- Easy to Use – You Can’t Really Mess Up
- No Prep or Setup – Open the Package and Go
- Some of the Best Germination Rates of Any Method
Cons of Rapid Rooters
- Can only get 50+ at a time (General Hydroponics currently does not offer fewer plugs per package)
- After opening the package, you only have a week or two before they dry out, so if you’re only germinating one or two seeds, you’ll end up having to throw many of the Rapid Rooters away.
There are a few different options for Rapid Rooters, which can be confusing if you’re not sure what you want. The 3 different options for Rapid Rooters are listed here…
Bag of Rapid Rooters
These are round on bottom instead of being a cube, which means they cannot stand up on their own. These are best suited to a hydroponic setup where the Rapid Rooter will be placed directly in the final destination. In our hydroponic setups, we’ve had near 100% germination rates with Rapid Rooters, better than any other seedling cube we’ve tried.
- Round on bottom (won’t stand up by themselves without support) unless you squish the bottom so it’s flat like this grower did (pic)
- Great for starting with Rapid Rooter directly in final destination (hydro, soil, coco coir, etc)
- Get 50 Rapid Rooters at a time
Rapid Rooters Mat
This type of Rapid Rooters comes in a mat of (usually 98) Rapid Rooters. All the individual Rapid Rooters are sectioned off and have a hole for the seed, but they must be cut or pulled away from the complete mat. Unlike the type of Rapid Rooters that comes in a bag, these ones are made into cubes, and are flat on bottom so they can stand alone. This makes them good for germinating in a shallow pool of water where the cubes need to be able to stand up on their own.
- Easily break cubes off the mat (already sectioned off with precut holes)
- Already shaped like cubes with flat bottoms, so they easily stand up by themselves
- Good for seamlessly transplanting your seedlings somewhere else
- Get 98 Rapid Rooters at a time
Rapid Rooters Tray
The Rapid Rooters tray is perfect for seeds or clones. Allow your young plants to sit in the tray with water until their roots are well formed and ready to be transplanted to your final destination. The standard size tray fits most humidity domes. You can refill the tray with Rapid Rooters from the bag or mat.
As you can see in the pictures below, the Rapid Rooter Tray comes packaged up. Once you open the package, you will see 50 Rapid Rooters already set in the tray. The resing place for each Rapid Rooter has a hole on the bottom so water within the tray is wicked up. The top part comes apart from the bottom.
Just add your seeds and pour some water into the tray – the Rapid Rooters will do everything else for you.
- Perfect for cloning or starting seeds with a humidity dome (standard 10-inch by 20-inch dome like this one – 7-inch height recommended for cannabis seeds or clones)
- Easy to transplant to new destination
- Just add water and seeds, that’s it!
- Whole tray can be refilled with any type of Rapid Rooters (from bag or mat)
- Comes with 50 Rapid Rooters, ready to go
One option for growers is to use a tool which has been specifically designed to provide optimal germination conditions like this germination station with heat mat.
You can make a DIY germination station at home by putting a plastic dome over a plate of Rapid Rooters on a heating pad.
There are benefits to the professionally made germination stations as they work very well and are pretty cheap to buy.
Rockwool Cubes (Not Recommended)
It’s often hydroponic cannabis growers who use rockwool cubes since these can be safely placed in hydroponic setups, hold a lot of moisture, and are resistant to mold. Rockwool is cheap and easy to find. It comes in convenient cubes. But it does have some major drawbacks…
Pros of Rockwool
- Cheap & Easy to Find
- Inert Medium (useful for hydroponic growers)
Cons of Rockwool
- Bad for the environment (unnatural material that does not break down)
- Bad for your health (especially your lungs) – wear gloves and cover your mouth/eyes when handling rockwool
- Has a pH that is too high for cannabis, so it must be thoroughly rinsed and treated
- Poor cloning and germination rates
- Difficult for new growers
If you do use rockwool, it’s recommended you germinate your seeds using another method like the paper towel method, then transplant your seeds to the rockwool cubes after roots have already appeared.
I highly recommend using Rapid Rooters instead for your hydroponic application (or any grow setup), as they are much more user-friendly and tend to get far better germination rates.
Jiffy Pellets are used in a similar way to rockwool cubes, though these tend to get much better germination results. Jiffy pellets are not suitable for most hydroponic setups where the roots are grown directly in water, but Jiffy Pellets can be directly transferred into soil or coco coir or soil.
Pros of Jiffy Pellets
- Good Germination Rates for Soil and Coco Coir
- Good for Cloning
- Come in dried pellets, so they can be kept for a long time
Cons of Jiffy Pellets
- Not suitable for hydroponic setups
- Must be soaked to expand each pellet before use
Once the compressed Jiffy pellets have expanded in warm water, gently squeeze excess water from each pellet and you’re ready to go. Treat them the same as Rapid Rooters.
Next: How to Germinate Marijuana Seeds Method 2: Plant marijuana seeds directly in growing medium.