How To Sprout Cannabis Seeds Using The Soaking Method

How to Sprout Cannabis Seeds Using the Soaking Method (Best for Old or Hard-Shelled Seeds)The soaking method (also called the “glass of water” technique) is one of the most reliable ways to germinate older seeds or those with particularly tough outer shells.

It’s simple, requires almost no equipment, and lets you visually check viability before moving to the next step.Here’s exactly how to do it:

1. Fill a clean glass with room-temperature distilled or filtered water (tap water works in most cases, but avoid heavily chlorinated water if possible). The ideal temperature is 20–25 °C (68–77 °F).
2. Gently drop your cannabis seeds into the glass. Don’t overcrowd — give each seed space to swell.
3. Place the glass in a dark, warm spot (like a cupboard). Avoid direct sunlight.
4. Let the seeds soak for 18–32 hours maximum. Never exceed 32 hours — prolonged submersion can deprive seeds of oxygen and cause them to drown before the taproot emerges.

What to expect:

• Within the first 12–24 hours, healthy seeds will absorb water, swell, and most will sink to the bottom. Sinkers are almost always viable.
• Floaters after 24 hours are usually duds, though you can try gently pressing them under the surface for a few more hours to be sure.
• Very fresh or thin-shelled seeds (especially autoflowers) sometimes crack open and show a tiny white taproot right in the glass — that’s a bonus!

5. Once the seeds have sunk or have been soaking for 24–32 hours, carefully remove them with clean tweezers or pour through a strainer.
6. From here, transfer to damp paper towels to finish germination (most popular), or plant directly into your growing medium with the crack facing up.

This pre-soak gives stubborn seeds a gentle rehydration and a strong head start, dramatically improving germination rates on older stock.

Want step-by-step photos and four other proven germination methods?
You can get the whole story (and other methods of germination) at How to Sprout Marijuana Seeds.