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starting marijuana seeds in rockwool cubes

Rockwool cubes become saturated with water when you soak them, but it quickly drains away. Each cube contains many small spaces between the fibres that help to effectively drain water.

There are many benefits to growing cannabis with Rockwool, especially when doing so hydroponically.

How To Use Rockwool To Grow Cannabis

In this guide, you’ll learn everything you need to know about this robust material. Find out why to use Rockwool in both hydroponic and soil systems, how it works during every stage of the growing cycle, and much more.

The structural integrity of a Rockwool cube will also deteriorate after a single round of growth. As the thick and strong main roots develop, they’ll make holes in the cube, in turn making it less able to accommodate another set of roots in the future.

Rockwool is a branded form of mineral wool, a material used primarily as thermal and acoustic insulation in the construction of homes, hospitals, recording studios, and even stadiums.

3 days. Once the first true leaves emerge, we want to select for the strongest one (the one that grew the tallest), and cut off the tops of all other seeds that are growing next to it. Do not pluck them out, as you may uproot it’s neighbors. Simply cut it off as close to the hole as you can without messing with the stronger one that you plan on keeping alive.

About 2-3 weeks after germinating, you are ready to transplant these babies into the hydroponic system of your choice. A good rule of thumb to go by is that you want to transplant them once the first roots begin poking out of the Rockwool cube. Don’t wait too long though, as eventually the roots will begin tangling around the cube since it is their only source of water. You want to catch them right as they pop out, so that when you transfer them into your hydro system the roots will grow down into the system, and not just try to feed off the Rockwool cube alone.

Fill the container/bowl with water from your tap. You may also choose to use water filtered through a britta or reverse osmosis (R/O) water, I’ve had success with all 3 of them so whichever you have on hand will work fine.

Important: Do not let the PH of the water go below 5. A Ph this low will damage the fibers of the Rockwool Cube

Take 1-2 seeds and insert them carefully into the holes. Use a toothpick or similar object to push them down to the bottom, as you want them to be at the bottom of that hole. Rip or push a piece of the Rockwool over the hole (you don’t have to fill it completely), so that the seed can germinate in a dark moist environment.

Using either a PH test kit or a Ph meter, determine the Ph of the water. Water comes out pretty alkaline, usually around 7.4, so you will need to acidify it a little bit to bring that Ph down to the desired level. Aim for as close to a Ph of 5.5-6 as you can get.

Most Rockwool cubes come with holes in them, if yours did not, than create a hole in one side that is approximately a quarter inch (0.75 cm) deep.

In this lesson, we will learn how to start your own seed with Rockwool Cubes. Below is a detailed guide to success with Rockwool, and a step-by-step video tutorial can be found at the bottom of the page.

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This method increases germination rates because the seed is primed, it’s already absorbed water and broken dormancy, so is ready to push out it’s first roots.

Best Way To Germinate Weed Seeds

Using either a PH test kit or a Ph meter, determine the Ph of the water. Water comes out pretty alkaline, usually around 7.4, so you will need to acidify it a little bit to bring that Ph down to the desired level. Aim for as close to a Ph of 5.5-6 as you can get.

If you don’t plant deep enough, the seedling may dry out, or never become moist enough to germinate.

For hydroponics, rockwool is the better choice.