A YouTuber (TBD) below discovered that you do not need an entire (expensive) Rockwool cube to start seedlings. He tried 1/2 a cube and it worked, then a 1/4 cube and it worked finally down to a tiny amount of Rockwool and it still worked.
Sweet Peppers, Cherry Tomatos and Roma Tomatos
Process:
- Cut each cube into 9 parts, similar to the divisions of a Rubrik’s Cube.
- Take several plastic food storage trays, carefully drill about 10 holes holes in each
- Stuff a bit of cube in each hole.\
- Add water to the tray to the level of the cube bits
- Place a seed directly on top of each cube bit
- Mist the seeds and Rockwool with more water
- Put the trays in a place that plants like
- Repeat the last few steps every day
Depending on the plant type, seed should start sprouting within a day or at most a couple of days. Keep up the daily maintenance until the seedlings are tall enough to be transferred into your hydroponic garden.