How Do You Germinate Cannabis Seeds for DWC?

Why

Some growers start in a damp paper towel, then move the sprouted seed into a plug. Others give the seed a short water soak before planting. You can also sow straight into a starter plug. All of those can work. I'm going to focus on how I do it, and you can choose what fits your setup.

Whichever route you use, the seed has enough stored reserves to sprout without added nutrients. Once true leaves are growing, an inert plug cannot feed the seedling indefinitely.

For my setup, I put each seed directly into a moist Rockwool cube in a covered germination box. I can move the whole cube into my RDWC net pot without handling a bare root. I've been doing it this way for years, and only one seed has failed to sprout. That's what has worked for me, not a controlled comparison of methods.

My box sits inside the tent on a heat mat. I aim for about 77 to 78 degrees Fahrenheit at the cubes and 80 to 90 percent humidity inside the dome. I keep the cubes moist without leaving them constantly waterlogged. Once seedlings emerge, I start ventilating as they develop.

The buried seed doesn't need bright light to sprout, but have the grow light ready when the seedling emerges. A practical starting point is 18 hours on, six off, at about 100 to 200 PPFD measured at the seedling tops with the dome in place. Increase light gradually as true leaves develop, and make sure the light isn't overheating the covered box.

I move a seedling when roots are visible outside the cube, the seed leaves are open, and true serrated leaves are actively growing. The intact cube goes into Hydroton in the net pot. At first, those roots will still be above the RDWC solution. I raise the water level so it wets the lower Hydroton, giving moisture a path through the pebbles toward the young roots. The check is whether the cube stays moist without sitting submerged. Once the roots reach the aerated solution, they can draw water directly.

So pick a starter you can manage well and plan the move into DWC. My direct Rockwool method keeps that move simple, but it isn't the only workable way.

Once roots reach the aerated solution, the water sits below the net pot with an air gap.

Related Grow Answers: When Is a Cannabis Seedling Ready for DWC? https://www.growpops.com/grow-answers/when-is-a-cannabis-seedling-ready-for-dwc Where Should the Water Level Be in DWC? https://www.growpops.com/grow-answers/where-should-the-water-level-be-in-dwc