Germinating Cannabis Seeds Correctly

Truth is, germinating Cannabis seeds is actually pretty easy, and seeds sown directly and shallowly in a suitable growing medium are likely to pop so long as soil moisture is kept high during this time.

Nevertheless, good seeds are expensive, so it pays to get the best germination rates possible. Accordingly, for optimal results, we suggest you use the following, 6-step “paper towel” method.

Step 1: Get Distilled or Reverse Osmosis Water

While you can certainly use tap water with good results in many cases, we suggest getting yourself some highly purified water, like reverse osmosis (“RO”) or even distilled water. Unlike most tap sources, RO and distilled water contains virtually nothing. This level of purity has two immediate benefits for germinating seeds: 1) with no soluble minerals in this water, it has a particularly strong tendency to move into and infiltrate the seed coat [remember that water diffuses from areas of low solute concentration to high concentration]; and 2) with nothing in it at all, this water tends to have an optimal pH of 7.0, which is just about ideal for promoting rapid, strong growth in the new start.

Step 2: Soak a Couple Sheets of Paper Towel

Take your water and pour it into a shallow tray or plate where you can soak a couple pieces of folded paper towel. Once the towels have become saturated, remove them from the tray and hold them upright so the excess water can drain off. Once the water stops dripping, you’re ready for the next step.

Step 3: Adding Seeds to Your Germination Container

While just about any shallow container will work, I prefer small Tupperware containers that have a tight-sealing lid. Take one piece of your moistened towel and place it on the bottom of the container. Now spread out your seeds on the towel so they are not touching each other.

Next, gently lay the other piece of moistened towel on top of the seeds. Lightly press the towel around the seeds so that they are completely sandwiched. There should be no air spaces between the seeds and the paper; the idea is to maximize contact between the seed walls and the paper towel to facilitate rapid water infiltration.

Now cover your seeds or add some plastic wrap over the tray to prevent water loss and maintain constant high humidity.

Step 4: Find a Suitable Place For Your Germinating Container

Cannabis seeds will germinate quickly at ordinary room temperatures, and therefore typically do not need any supplemental heat unless ambient temperatures are well below 68 degrees Fahrenheit, in which case a heating pad under the container can be used to raise temperatures to around 80 degrees Fahrenheit to speed up and improve germination.

Whatever you do, keep your seeds out of direct sunlight and otherwise avoid extreme temperatures.

Step 5: Begin Checking for Early Signs of Germination

In my experience, the earlier you catch the seed in the germination process the better. Seeds that have only five millimeters (or less) of root protruding when they are planted tend to adapt to new media faster, and with little or no “transplant shock.”

Given the benefits of early detection, I suggest you start checking your seeds no later than 24 hours after setting up your germination container, and continue to check every day thereafter. Remove and plant each seed as it germinates. Do not wait for them all to germinate before transplanting. Most seeds will “pop” with 3-5 days, although I will typically wait for a good two weeks before I deem a non-germinated seed a lost cause.

Step 6: Transplanting Germinated Seeds

Place the germinated seeds in a moistened growing substrate, root tip down. Plant them shallowly, only about as deep as the seed is long. Planting too deep will cause a seedling to exhaust its energy stores before it can reach and punch through the soil surface – where it can begin making its own food through photosynthesis.

Make sure that the surface layers of your media do not dry out! If in doubt, place a layer of plastic wrap or clear plastic cover/tent over the pot/media to retain moisture.

After Germination – Early Treatment of Cannabis Seedlings

If using a plastic covering over the pots to reduce water loss after transplanting – remove it immediately upon the first signs that the seedlings are beginning to make their way through to the surface. If you don’t, you are just asking for fungal diseases, such as “dampening off,” which can kill off all of your seedlings overnight. The seedlings should now receive strong lighting and good air flow, just as an adult plant would require. Remain vigilant with watering/misting, however. Remember that these young plants will still have only shallow, weak roots.

I want to stress how important it is to give your seedlings direct sunlight or strong artificial lighting just as soon as their leaves start to break the surface. Even a couple days in a dim corner can do significant, sometimes irreversible damage. This is where I see many new and even experienced growers often go wrong.

In addition to increasing the risk of dampening off disease, seedlings that are denied good light at the outset will quickly elongate and grow spindly and weak. Moreover, even if they pull through, these lanky seedlings never seem to catch up to, or match the growth rates of, other plants that were given strong lighting right from the get go.

If growing seedlings under HID fixtures, make sure the bulbs are far enough away (at least 16″ or more depending on wattage) to prevent burning of the seedlings and over-drying of the surface soil layers. For florescent fixtures, you will want the bulbs much closer to the plants to provide adequate light intensity, typically no more than 4-6 inches away.  If growing outdoors, acclimate seedlings to full sunlight by providing several hours of direct morning sunlight only at first, gradually increasing the duration daily until full afternoon sun exposure is tolerated.

Good Luck!

Photo Credits:

By thor under CC BY 2.0