Scarification, or scuffing the shell, can also help water pass through an older seed’s tough outer shell.
To scarify your seeds, line a matchbox or other small container with sandpaper. Drop the seeds inside, shake vigorously for 30–60 seconds, then remove. You may not notice much of a difference, but the small micro-abrasions are sometimes enough to let water breach the shell and trigger germination.
As cannabis seeds age, their protective outer shell hardens and prevents water from passing through. Unless the tiny, dormant embryo that lives inside the shell detects moisture, it doesn’t know that the conditions are right to sprout. As a first step, pre-soak your old cannabis seeds for about 12 hours to see if that does the trick.
In a life or death situation, surgery may be the only option. Meaning—only do this if nothing else has worked because this technique ruins as many seeds as it saves.
If you’re going to keep seeds more than a year or two, proper storage will dramatically increase the chances of late-stage germination. Place them in an airtight container. Put the container in a refrigerator set at 6–8°C with 20–30% relative humidity. If excess moisture is a concern, add silica gel packs to the container.
In order to store seeds correctly, you’ll have to provide them with a cool, dry environment. The idea here is to prevent the seeds from trying to germinate before you’re ready to stick them in the ground. Light, water, and heat are all things that help seeds sprout, so it should come as no surprise that you’d need an almost total absence of these things in order to store seeds for long periods of time.
Another way to coax the shell to break down a bit is to add some fulvic acid to your original water source. A concentration of about 10ml/L is suggested. Fulvic acid is a natural component of healthy soil. It’s an organic polymer that is extracted from humus. It helps further facilitate the breakdown of the marijuana seeds outer shell and also encourages healthy plant growth.
Bring Out Your Dead
This is a pretty common practice used to germinate almost any seed. Take a few moist paper towels and place the seeds you’d like to germinate on top. Place a few more moist towels on top of the seeds and seal in a container. Keep the container somewhere it will be warm and get a bit of light. Seeds should germinate in about 72 hours.
When all else fails, you may need to score (scratch or cut) the outer surface of the seed by mechanical means. This can be achieved in two ways: With sandpaper, or a steady hand and a sharp knife. If you’re going the sandpaper route, line a small container, like a matchbox, with fine grain sandpaper. Pop your seeds, around 30-60 at a time, and shake the container for a good three minutes. For the knife method- use an extremely fine blade, such as found on Exacto knives or scalp to create a shallow cut in one side of the seed.
To discourage any light from getting in, place the seeds in an opaque container. While it’s unlikely that the seeds will enjoy much sunlight in your crisper drawer, placing the seeds in a small container means that you can more readily control their immediate environment. On top of shutting out light and excess moisture, place small bags of silica gel in with the seeds. This will help prevent any excess moisture build up, effectively keeping your seeds viable for extended periods of time.