Despite our strong advice of germinating seeds on soil, however there are always people who’d rather use rockwool plugs.
If you want to germinate on rockwool plugs it is very important to level the pH-value of the plugs. Rockwool has a pH of more than 8, which is way too high for your young plants. To level the pH-value drown the plugs in water with a pH 5.2 and soak them for 24 hours. This will end up with the correct value of 6.3-6.5.
Now you can carefully put the seed into the hole of the plug and carefully press it 5 – 10mm down that all sides are surrounded by rockwool. It doesn’t matter in what position the seeds are after germination the plant grows up and the root grows down.
Germination of seeds is most succesfull with a temperature of 22 – 24 degrees. This will give the plant the best start. So after 2 to 4 days you will see your plants grow out of the plug. Make sure your plug does not dry out! So water regularly but don’t drown the plugs. Always use water with a pH of 5.8. Good luck!