How To Germinate Weed Seeds The Ultimate Guide

Every grower needs to know how to germinate weed seeds. Even if you think you are going to grow from clones forever, the day will come when you want to self a plant or have a plant produce a few seeds you want to try.

I am going to share the system I use for germinating weed seeds and also give a few growing tips to increase your germination rates.

If you are going to grow from seed you already know good genetics can be expensive. So when you do sprout your seeds you want to make sure to get a high germination rate.

Hopefully your seeds will be fresh. If they are you should expect a germination rate of 90%. Older seeds generally have lower germination rates. Older seeds often wont germinate well or will crack and then stall out without sending out a tail.

Really old seeds are a special challenge to germinate and usually need a soak in gibberellic acid or other hormones to sprout.

How To Germinate Weed Seeds Step By Step


I will be using Karmarado OG as the test subject and showing how I germinate them. This strain is a collaboration between Karma Genetics and another breeder. I received 15 seeds and because of scheduling and space issues they have been sitting in my fridge for about 6 months. So they are not exactly fresh.

How to Germinate Weed Seeds - Karmarado OG

I really want to see what this strain can do because it has some Triangle Kush in the genetics. So hopefully I will have a good run and eventually I hope get mostly females. yOU CAN FOLLOW MY Karmarado OG grow here: Karmarado OG Grow Journal Report – How To Grow Weed Indoors (

Normally you get a 50/50 ratio of male to female with a slight edge towards ladies. So assuming all 15 pop I should end up with 7 males and 8 females, but a lot is just luck in smaller numbers.

Germinating Feminized Seeds

If you can find female seeds in a strain you like go for it unless you are planning on breeding with them. Feminized seeds will save you time and space by not having to mess with male plants.

They are not any more hermi prone than the strain they come from but since they have no true male genes you don’t want them for breeding purposes.

There are a lot of different ways to germinate cannabis and I have tried most of them. Some work very well and some work better for certain grow systems than others.

I have a system for germinating marijuana seeds that works for almost all growing situations. I won’t tell you it’s the only way. As they say there is more than one way to skin a cat and this is how I skin mine. After trying many different methods I do think this is the best way for germinating cannabis seeds.

Some Common Ways To Germinate Weed Seeds

Probably the simplest way to germinate cannabis seeds is to direct sow them in containers. This can work if you grow in soil or coco but not for aeroponics or hydroponic gardening. I think you are smart enough to drop a seed in soil and lightly cover it without going into much detail.

One of the most common ways to start seeds is on a wet paper towel. Usually it is placed between two plates or in a small container with a lid. I have germinated seeds this way for years and had good results but it also has some drawbacks.

There two reasons I don’t do this any more. One is that the roots often can grow into the paper towel. Removing the germinated seeds without damaging the roots can be difficult, especially if you let them go a bit too long before removing them.

The other reason is very similar. Young weed seeds can be very delicate and it is easy to damage them when trying to remove them and again when planting them.

Here Is How I Germinate Cannabis Seeds

germinating weed seeds in a shot glass

My first step is to soak my weed seeds in a shot glass before germinating them. I do this for  about 16 hours.

Marijuana seeds don’t really need a dark place to germinate. Light will not bother them or slow them down. Warm, but not hot temperatures will speed up germination. About 75° is perfect for them.

How To Germinate Weed Seeds Tip 1

If you add a cap full of 3% H2O2 to the shot glass it will speed up germination. Also if there are any fungus or other seed borne diseases it will kill them. Don’t over do this or your seeds may pop right out of their shell as preemies.

If you use peroxide your seeds probably wont sink because the bubbles will hold them up. After about 18 hours they have absorbed enough moisture for the next step. I want them just before they are showing tails but are ready to sprout so I soak for 24 hours max.

Germinating Weed Seeds Tip 2

Some seeds have really tough shells that can make germination difficult. Cinderella is a good example. You can help germination by scarifying your seeds.

To do this you can line a small match box or other container with sandpaper and shake your seeds inside for a few minutes. An easy way to scarify seeds is to roll up a piece of sandpaper, rough side in, into a tube about as wide as a soda straw. Put a finger on the bottom, drop your seeds in and put another finger over the top and shake it for a while.

Planting Marijuana Seeds

The idea is to get your seeds planted before they have much of a tail and avoid breakage. I have planted in Rapid Rooters and in rock wool and both work fine. Rock wool is cheaper and works just as well and will stand up.

Rapid Rooters are unstable because of their shape although you can use them upside down and they are a bit more stable.

Personally I like Grodan 1.5″ Mini Blocks. They have flat bottoms so you can put them in anything. The wrap directs the roots down and protects them. It can later be planted in soil or used for aeroponic or hydroponic systems too.

grodan rapid

If you are going to use rockwool you will need to soak it in water with a pH of about 5.8. I don’t use any fertilizer for my seedlings. However I do add a vitamin and hormone booster that I get from MB Ferts. You can also use SuperThrive which is available everywhere.

Don’t Over Water

You don’t want your blocks soaking wet either. Soak them for a few hours and then squeeze most of the water out. If you don’t your seeds may rot because they aren’t getting any oxygen.

A lot of growers get carried away with watering. More is not better. Your seeds have already been presoaked so your medium should be at what is called field capacity. This is where soil is gently squeezed until no more water runs out but is still moist. This is ideal for starting seeds.

Next Direct Sow Your Seeds Into Your Preferred Grow Medium

I simply drop each seed into the prepared hole. Weed seeds have a pointed and blunt end. I roots and sprout will come out the pointed end. Don’t plant your seeds with the pointed end up if you can avoid it. Plant them pointed end down. Or even better just lay them on their side and they will be fine.

I put my seeds inside my grow tent close to the florescent lights so they get plenty of light and a bit of heat. My fixture has 8 tubes and about 400w and I put them about 8 inches below the light. They also get air circulation from my fan.

As cannabis seeds sprout it is a good idea to mist them. Don’t cover your seeds at this point or you could have them damp off on you. Covers are OK for clones but can cause more problems with germination than they solve.

Just mist them a few times a day if you can. You want high humidity to make it easier for the first leaves to be able to shuck their shell, but you also want good airflow.

Germinated Marijuana Seeds 2 Days Later


how to germinate cannabis seeds

So I had 14 out of 15 seeds germinate. I looked for #15 but could not find it. There were 16 rockwool cubes in the tray I used. I checked the 2 empty blocks but couldn’t find it. So I either double seeded one cube or lost it somewhere during planting, duh!

Still even without it 14/15 is a pretty good germination rate. So I will have 14 Karmarado plants to work with.

Karmarado OG Seedlings 2 Days Later

How To Germinate Marijuana Seeds

One plant in far upper right corner took an extra day to bust out and so it is a bit smaller than the others. Right now they are a few days away from being large enough to go into net pots and then they will go into my low pressure aeroponic system.

Feed Lightly Once You Have 2 Sets Of True Leaves

I do mean lightly too. Young seedlings like those above are very easy to overfeed and burn. I give seedlings 250-300 ppm of CaliMagic at this point. OGs and OG hybrids need magnesium almost right away. They also need calcium. Calcium is not very mobile within the plant so it is important to start getting it into the plant very early.

The Karmarado OG will go for about 3 weeks to a month in veg mostly because I have to wait for slots to open in my flower room. Ordinarily I like to go to straight 12/12 with seedlings so I can find out which ones are males. I will be updating and documenting my grow once they go into flower.

So now you know how to germinate weed seeds and improve your germination rates too. Happy growing and stay green.

4 thoughts on “How To Germinate Weed Seeds The Ultimate Guide”

  1. First, I want to thank you for having such great (and detailed) information on this website. You gave me the confidence to attempt HP Aeroponics. My question is, do you (carefully) remove the seedlings from the rockwool? Or do you put the cube into the net basket undisturbed? My concern is too many rockwool particles in the system creating more potential for clogging. Thanks again for all the effort you have made to educate others on DIY aeroponics.

    • Hi Jill,
      Glad you are giving it a go. You will love the results. Please don’t try to remove the plants from the rockwool or you will damage the roots. Just place the cubes in the net pots and the roots will grow down just fine. If you use a filter bag like I do nothing will get in the lines. If you are really concerned about this you can try using Rapid Rooters instead. The cost a bit more but won’t give off any particles at all.

      Good luck with your grow!

  2. I was so inspired by all your info I’m putting together a HP as you suggested hopefully for oil production for a cancer patient. Thank you.
    I have 6- 3 inch net cups installed on the tote and plan on starting from seed since I’m unable to source any clones and am using 1.5″ Grodan blocks. At what point do they go into the HP aero tote ? Do you just set the block in the net cup loose fit or fill in with more rock wool or use the neoprene collar?
    Yours is the best site for this info and I’ve looked at all I could find , Thanks . I appreciate it. JBN

    • I only use neoprene inserts. You don’t want to pack the net pots with rockwool because it holds a lot of water and could cause stem rot. Ideally as soon as roots are poking out they can go in net pots but not before they are tall enough to poke through the top of the insert.

      You are going to need a TDS meter and pH pen for sure. For seedlings start at 300ppm and during veg raise it to 600. For flower about 900 but it is strain dependent, some plants are light feeders others are heavy. A pH of 5.8 is the sweet spot for aeroponics but don’t freak out if it goes a bit higher or lower.

      I don’t use veg nutes, not really needed. I use flowering nutes with some added cal/mag. You might try Canna Aqua it is for recirculating systems and pretty pH stable. Hope this helps and good luck on your grow. Don’t give up, there is definitely a learning curve. People say it’s just a weed. Wrong! It is a very resilient plant so anyone can grow crappy weed but growing quality cannabis is as much an art as science.

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