This guide will show you how to germinate seeds for DWC (Deep Water Culture) growing.
Starting from clones is much easier than starting from seed when it comes to DWC. Seeds are fragile and require extra care when being propagated for hydroponics. This is probably the one area where soil growers have an edge over DWC. Since soil typically contains trace nutrients simply plopping a seed in moist soil is usually all it takes to get a healthy 3-4″ plant.
Overview
Materials Required for DWC Germination:
- The Doc’s DIY Aeroponics Cloner
- Paper Towel
- Cannabis Seeds
- Foam Collars
Paper Towel Germination
Start your DWC germination using a moist paper towel. Wet 2-3 sheets of paper towel using tap water. I don’t bother with adjusting pH this early into the grow. Ring the paper towel out so that it is moist but not dripping.
Spread the seeds out over the paper towel and fold over so that the seeds are sandwiched by at least two layers of paper towel. Work with clean hands and minimize air exposure after soaking.
Put this somewhere warm, 80F is ideal for germination but in my experience, anything above 65F will work fine.
Top of the fridge is an oft-recommended spot but when I actually tested surface temperatures in my house the top of my fridge was about 5 degrees colder than the top shelf in my pantry
If you live in a very cold climate like me and my fellow Canadians you can put the seeds in the oven with the light on to generate a bit of heat. Goes without saying you should put a sign up if you are using the oven method!
After 1-2 days the seedlings should crack and the taproot will begin growing. Leave them a few more days.
After 3-5 days the taproot should be over 1″ long. This is when they are ready for transplant. The seeds were a freebie so I’m ok with the 66% success rate. Typically, you should have 90% or greater germination rate for high-quality genetics.
Rockwool Sleeve
EDIT: Since writing this post I have tried inserting the rooted seedling directly into the foam collar and found it works just as well. IMO the rockwool sleeve is not necessary.
What I do next is something I came up with out of necessity. A full rockwool cube I find to be unnecessarily large. If you’ve read my DIY Cloner article you’ll know that I feel Rockwool can create a low oxygen environment where pathogens thrive.
Rockwool serves a purpose for hydroponics germination. It helps protect fragile taproots and holds water between spraying.
Start by soaking your Rockwool in pH 5.5 water.
Take a Rockwool starter plug and cut it into 4 long strips. Use a clean knife to cut a slit in these strips.
Place the germinated taproot into the slit that you created.
Rockwool Sleeves for Foam Cloning Collars
As per my DIY cloner article I prefer foam collars over neroprene. The foam holds up better and surprisingly absorbs less water.
Trim the foam collar to create room for the Rockwool sleeve
Aeroponics Cloning Nutrient Solution
- 1 Gallon Water
- pH down (Target pH 5.5)
- FloraMicro 3 Part Series (1 mL each Micro, Gro & Bloom)
- 1.2 mL of Rapid Start
A few drops of pH Down gets me down to 5.5
Unlike soil (which has trace nutrients) cloning/germination in hydroponics requires immediate additions of nutrients. Once you get the pH to 5.5 add:
- 1.2 mL GH Rapid Start
- 1 mL of FloraGro
- 1 mL of FloraMicro
- 1 mL of FloraBloom
My starting ppm was 100 and the final ppm was around 300.
Seedling Growth
From here the process is the same as with clones. Simply run the pump on a cycle timer and let nature do its work.
The plants will not look happy on day one, but don’t worry they will perk up quickly under the light.
Rockwool Watering (Why I started using aeroponics for germination)
This video shows how quickly Rockwool cubes can dry out. Without using the aeroponics cloner I needed to water the seedlings multiple times per day, even with the humidity dome! You can also see why I have the plants so close to my light now. Fluorescents are not very strong and can cause extreme stretching if they are not within a few inches of the plants.
