As I said in my last post, who needs soil to grow plants? Rockwool is the perfect soil substitute for plants. In this post, I discuss the beneficial properties of Rockwool and learn how to use Rockwool cubes for seeds starting in hydroponic systems. You really should try these Rockwool cubes for seed starting. They are inexpensive and reusable too.
But What Exactly is Rockwool?
Rockwool is produced by combining basalt rock and chalk then melted at a very high temperature. At around 3000°F, the mixture forms fluid lava. The lava then enters into a spinning chamber to create the fibers as it cools down. It is kind of like a process similar to making cotton candy.
Why Is Rockwool Used by Hydroponic Growers
Rockwool has a beneficial structure for plants because it retains water and holds more oxygen when compared to other soil mediums. It is evident to most readers that plants need water, but it is just as crucial for plant roots to have access to plenty of oxygen. This increased capacity to hold water, along with the added benefit of oxygenation within the plant’s root zone, is very helpful when starting seeds and cutting propagation. These characteristics of Rockwool make it the ideal growing medium.
Additionally, Rockwool is chemically and biologically inert. In short, that means that it does not interfere with or alter plant growth in any way or harbor bacteria or fungi, which could infect and damage young seedlings. These overall benefits contribute to its popularity amongst growers, accommodating almost any plant they like to grow.
Seed Starting Using Rockwool
Rockwool is popular with the hydroponics growing community, and it is commercially sold (Amazon) as cubes of various shapes and sizes. There is a bit of a learning curve when it comes to Rockwool, but the benefits are worth it, and at the same time, you are picking up a new gardening skill. In this post, I am using organic lettuce seeds that are easily inserted into holes in 1.5-inch presoaked cubes. Eventually, as the plants mature, they are transferred to a deepwater culture hydroponics system. If you are just starting out in hydroponics, I recommend growing lettuce because it’s easy and gives quick results. This happens to be Black Seeded Simpson, a variety purchased from Park Seed, a company known for its quality products.
Some Do’s And Don’t When Using Rockwool
- Do wear protective gear to keep yourself safe when handling Rockwool material. These fibers can be irritating to skin, eyes, and lungs.
- Do not squeeze the cubes when they are wet because it can damage the internal structure.
- Do take the time to properly prepare Rockwool cubes before starting seeds. Rockwool has a naturally high pH, typically around 8.0, which is too high for many plant types. You need to follow the procedure for adjusting its pH down.