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planting marijuana seeds in rockwool

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.

Some people claim they use a diluted nutrient solution to water their Rockwool cubes with during germination. Do not do this, as my experience has always been negative. Note the picture below, where I did an experiment by adding a very diluted grow nutrient to the Rockwool cube on the far left. It died within an hour or two, and the others went on to live happy lives. In my opinion, they do not need nutrients until they get into your hydro system.

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

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

Items you will need:

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.

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.

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 would have soaked mine over night first 75 percent of time is split the next day

germinate them what ever method you prefer to use,

Also, rock wool is naturally alkaline, so you’ll need to soak it in PH balanced water over night first before putting ANYTHING in it. My plants are currently in rock wool and doing great

Well-Known Member

from there go to paper towel all in dark on heating pad at about 80 degrees

the paper towel method ALWAYS works. IMO

It’s easy:
get 2 paper towels
fold them in half together
place the seeds in-between the folded area
dampen the paper towel (damp, not dripping, but not too dry either)
place the damp paper towel with seeds in a ziploc bag
put them somewhere dark for a couple days
ta-da!

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.

The differences are subtle, but very important depending on how you plan to grow your plants after germination.

Here is what it should look like:

Best Way To Germinate Weed Seeds

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.

Get a bowl or some other container that is big enough to fill with water and have room left for your Rockwool cubes. Your average salad bowl will work fine for 3 Rockwool cubes, if you are planning on doing more than you will need a larger container.

This will essentially starve and kill your seedling.