A relatively new growing medium, Rockwool originated in Denmark and is comprised of spun rock and sand, allowing the medium to retain great amounts of water. It also holds onto air, which is perfect for newly transplanted clones with vulnerable roots, and also comes in many shapes and sizes.

However, Rockwool also comes with some drawbacks: it never decomposes, can be hazardous if its fibers or dust particles are inhaled, and has a high stadning pH. Therefore, it isn’t the most popular growing medium in the hydroponics world and some even refer to it as the “styrofoam cup of hydroponics”.

But growing mediums are a personal preference, and newly rooted baby clones can be transplanted into Rockwool cubes rather quickly after developing. The following guidelines will help ensure your baby clones’ success when taking the Rockwool cube route:

Guidelines for Rockwool:

-Size€” – Short and Sweet: Roots needn’t be super long before being transplanted into Rockwool. In fact, the sooner they’re transplanted after the bare roots develop, the better. They should be between 1/2 to 1-1/2 inches long and transplanted into 1-1/2 inch cubes, or larger if desired.

-Water – Adjust the pH of the water you’ll be dipping the Rockwool cubes into between 5.5 and 6.5, as Rockwool inherently carries a high pH level. Then, dip the bottom quarter or half of the cube into the water, allowing it to uptake an ample amount without becoming soaked or over saturated.

-Resist the Urge – Do not squeeze, squish or otherwise manipulate the cubes’ shape. This can disrupt the air/water ratio balance.

-Safety First – When separating the Rockwool cubes from the mat, use scissors and wear gloves, as the fibers can latch onto and dig into your skin. Gross!

Depending on the stress caused from transplanting, consider misting the clones immediately after transplanting. This isn-€™t necessary, and plants often become stronger when allowed to fend for themselves, but misting can sometimes limit undue stress.