Why are runner roots coming out of my rockwool cubes in my hydroponic garden?

By Armando Suarez | Last updated: May 26, 2021

rockwool cubes

A: In nature, seedlings will project their roots as fast as possible into the ground to anchor the plant and start searching for nutrients in the soil. In rockwool cubes, the task is greatly facilitated because the fibers lend themselves to root penetration, and water and nutrients are immediately available.

If you have roots coming out the bottom, if they are suspended in the air, they will air prune. Otherwise, you can give them a trim to promote branching inside the block. Also, if you observe runner roots that are already two inches outside the block, it means the block is sitting in a puddle of water, which is not recommended for a few reasons.

First, if you have those runners, it means you don’t have roots branching in the block and the plant is expending its energy on creating roots to go after the water. Second, when roots are sitting in water, you are creating perfect conditions for root rot to occur, given that the block is probably saturated with water and not letting roots breathe.

The best growers are the dry growers. You could elevate the blocks above the surface where they are sitting. This way, gravity takes care of any excess water and the roots will prune themselves.

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Hydroponics Root Health Plant Growth Growing Methods Grow Media Plant Health

Written by Armando Suarez

Profile Picture of Armando Suarez
Armando has worked with plants since he was a teenager, working in a nursery. He later graduated with a BS in farm management and agricultural engineering. Armando currently works for GRODAN where he is actively involved in helping his clients design and optimize their facilities to grow the best quality crops possible.

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