RootIT cubes germination guide

Garden centres and hydroponic grow shops sell germination cubes. There are several different brands, but they are all made from a sponge like material which retains moisture but is soft enough to allow small roots to develop and grow.  Various materials have been used, including glass wool, coco fibre and synthetic polymer sponge.

Follow the advice on the cubes, normally you wet them with water (some prefer to use bottled water) or buffered water.  The seed is pushed about 5mm below the surface.  The damp germinating cube is then placed in a sealed sandwich box/bag to retain the moisture.  The seeds often germinate within a couple of days, but may take longer.

Out of the best ways to germinate cannabis seeds, germination cubes are one of the preferred ways to get maximum germination rates.  Once the seed has germinated the cube is simply transplanted into the next container to grow.

How to germinate seeds with germination cubes

Important information:

Avoid pulling the seed casing away from the seedling as this can damage the seedling. Its always better to wait until the seed case dries out and falls off naturally. Ripping the seed casing away from the first set of baby leaves (cotyledon) too early damages the young seedling and can kill it. Germination can take 3-10 days depending on environmental conditions and variety.

Step 1: Get a germination cube box from the shop

Prepare your pots with clean fresh soil. It is often easy to use small pots for this, and transport them to a larger container later.

Step 2: Water the cubes

Step 3: Place the seeds inside

Step 4: Wait for germination

Make sure to let some fresh air go into the box.

Step 5: Watch your seedlings grow

Make sure to let some fresh air go into the box.

Step 6: Place the cube in a grow medium

Gently place the cubes in a larger grow medium.

6 Comments. Leave new

  • Stuart P
    06/02/2020 19:59

    I grew my auto Colorado cookies seedlings inside a small tent under a tube light. They grew and sprouted leaves. Roots came through and I transplanted to larger cubes. Left under small tube light till roots came through the bottom of the larger cube. I put them into large grow tent on a hydro set up. They have small thin roots but leaves have dropped and gone light. They look like they are dying. Growing under led telos 008 lights. Lights about 80 cm away from seedling. Any ideas how to save them.

  • Will this method work for autoflowers? The main concern is shocking them as i guess this is similar to a transplant. Thanks in advance.

    • It would work but indeed it is better to germinate autoflowers in a larger container so their main root can grow freely 🙂


  • Hi. What size of rockwool would be best for autoflowers?

    • Hey Mark,

      Best would be if it is not a to small container for an autoflower to start in. We would like to help you with some more detailed information. Would you please send us a message at [email protected]?


      Dutch Passion


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