We recommend a two step process that will optimize your germination rates. For the 1st step, you will pre-soak your seeds directly in water for 24 hours. Then you will complete germination by folding your seeds in damp paper towels for approximately 48-72 hours. The 2 step process helps you get the highest germination rates from your seeds by providing ideal exposure to water, air and heat.
The goal of the 1st step, soaking your seeds in glasses of water, is for ensuring water penetrates your seeds’ hard outer shell barrier. Cannabis seeds in the wild naturally have a hard outer shell because they are shed in the fall and need to survive the whole winter before sprouting in the spring. Water must penetrate the protective shell and reach the embryo for germination to start. A 24 hour soak allows water to penetrate even stubborn seeds, to begin the process of germination.
If seeds are left in water for longer than 24 hours there is a chance they will get waterlogged and the embryos will drown. To avoid killing seeds, after 24 hours move them to damp paper towels instead. Damp paper towels continue to provide moisture which is critical for germination, and they also prevent drowning by allowing some air to reach the seeds as well.
Some growers use only the paper towel step for germination. This will work for most seeds. However, by adding a pre-soak at the beginning, our recommended 2 step process increases your germination rates because it does a better job at delivering moisture for your outlier seeds that have tougher than average outer shells.
Step 1: Pre-Soak Your Seeds In Water
Add water and seeds to clean glasses that have been washed and thoroughly rinsed with no soap residue. You can use tap water if you adjust pH to 5.8 and dechlorinate it first. Or you can use distilled water which is already pH neutral and has no chlorine. It’s best to add only a small amount of water because less water makes it easier to retrieve the seeds from the glasses later. Leave the water to stand until it reaches room temperature before you add seeds to it.
For higher germination rates, add kelp extract at a rate of 0.2 gram per gallon to the water. Kelp extract contains gibberellic acid which helps seeds germinate. Older seeds especially will benefit from adding kelp to the pre-soak water.
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Seeds must be warm or else they won’t germinate. Place the glasses of seeds on a heat mat to add warmth, with a towel down on the heat mat first to prevent the bottoms of the glasses from getting too hot. Drape another towel over the glasses to trap in warmth and block light.
After 24 hours, remove your seeds from the glasses. Pour the seeds and water out of the glass, being careful not to lose the seeds in the process. If you filled the glasses shallowly, it shouldn’t be difficult to extract the seeds with your fingers. If you need to pour some water out of the glasses to get the seeds, do it over a bowl or use a strainer so the seeds don’t escape with the wastewater. When using your fingers to move the seeds be careful not to cause any damage to any taproots that have emerged. Move the seeds right away to damp paper towels
Step 2: Germinate Seeds In Damp Paper Towels
Prepare paper towels by folding them into small squares. Soak them with distilled water, or tap water that has been pH balanced to 5.8 and dechlorinated. The paper towels should be moist, but not waterlogged. The right level of moisture is when they are wet, but there is no pooling water, or water dripping off of them. If you need to get rid of some water give the paper towels a light squeeze.
Fold your seeds inside the folded damp paper towels and put the paper towels with the seeds into plastic bags. Leave the bags open to allow some air to get in.
A very small amount of excess water inside the bags is okay because it helps prevent the paper towels from drying out from evaporation. Not too much water though, because pooling water can cause your seeds to drown.
Next, fold the seed bags inside a tea towel, then place the tea towel onto a heat mat. The tea towel acts as a buffer, preventing excessive heat. The heat mat should keep the seeds at the ideal temperature of 20° – 26°C (68 – 78°F). Lower temperatures can stunt germination.
The damp paper towels should stay moist for up to 2 days, which is usually enough time to complete germination. If the seeds need more time and the paper towels start to dry out, replace them with fresh damp ones.
All your seeds should be spouted and ready for planting within 48-72 hours in the paper towels. Check your seeds every 12-24 hours and plant them when the the tap roots are approximately 0.25” – 0.5”, (0.75 – 1.25 cm). If the taproot gets too long it is more difficult to plant, and more likely to get damaged. Transplant immediately when sprouts are the ideal length.