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how to start marijuana seeds in rockwool

Cannabis plants have different nutritional demands during the flowering stage. Clean out your hydroponic nutrient reservoir and fill it back up with a flowering formula. If you’re growing in soil, start watering your plants with bloom nutrients to ensure big, healthy buds.

However, healthy soil doesn’t just contain organic substances. Vital minerals and elements required by plants are inert by nature. Some of these are locked away inside of Rockwool and will eventually end up inside your cannabis plants, where they’ll enable and support key physiological functions.

Don’t place your Rockwool cubes too close together when raising seedlings. The material allows for water to drain and for air to flow through. Don’t lose this advantage by overcrowding your trays.

2. Don’t Squeeze Your Cubes

Rockwool harnesses the power of natural stone to produce a fluffy and aerated growing medium ideal for cannabis growing. This material drains well, supports root development, and arrives in a cuboid shape that is easy to transplant into hydroponic or soil-based systems.

Rockwool also poses a potential health hazard to growers. New Rockwool cubes can contain a lot of loose fibres and dust. These particles can end up in the air, and even on your skin and in your eyes, mouth, and lungs. Much like asbestos, tiny fibres can build up in the lungs over time if you work with new Rockwool cubes every day.

The process of making Rockwool cubes also takes a toll on the environment. In addition to the endless quarrying of basalt rock, it takes a considerable amount of coal energy to heat furnaces and power the machines needed to process the whipped-up lava wool.

If you’re growing a photoperiod plant, you’ll need to switch your light cycle to 12 hours on and 12 hours off to force them to flower. If you’re growing outdoors, nature will take care of this for you. Keep autoflowering varieties on a light cycle of 18 hours on and 6 hours off if growing indoors.

Do not add any nutrients to your Rockwool Cubes. The one on the left got nutrients, the other two did not.

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.

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.

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

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.

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.

They should look like this:

Depending on how hot it is (and other factors) you may need to water your cubes 1-4 times a day. Use the Ph adjusted water when doing so (that’s why I had you save the leftovers from step 2). If you already threw that water out, go make another batch of Ph adjusted water and keep it in a separate bottle or container for watering. Note: Do not over water, in fact while some say to water 1-4 times a day, I did it only once a day when I got home after work.

I use the paper towel method 100 percent success rate for me, then once the little white tail pops out of the seed, then move the seeds to the 1 inch rock wool with the tail facing down in the hole then lightly put a little piece of rock wool over the hole that the seed is in.

seedlings in them you would not have to water for about a week maybe longer.

Humboldt14

germinate them them move them to the rock wool cubes

seedlings in them you would not have to water for about a week maybe longer.

Pre-sprout your seeds in a moist paper towel and then plant in the rock wool once the spouts are over 1/2" I did this and got 14/20 sprouted from which I had to pick 7 and they are all doing AMAZING.