I have been gathering materials for a hydro setup – 400w metal halide light for the 1.2 x 1.2 x 2.2 meter room, fan, reflective liner for walls and a hydroponic system for 5 plants, 30-liter tub, the whole deal. I know how to germinate seeds in soil. But I am interested in something more. How do I plant in hydro rocks and how to fertilize? What fertilizer to use? You know, how to for dummies.
The 400w lamp will be perfect for your small room. You could use a bigger light, but, if you do, heat could easily become a problem, and you would have to add more ventilation. Planting in Hydro clay (what you call hydro rocks) is easy, but you will have to change from soil to rockwool or Jiffy pellets for best results. Place seeds in a moist paper towel or cheesecloth, making sure they are in darkness. Set the moist cloth or paper towel on a dinner plate. Water daily and keep evenly moist. Let excess water drain away freely. The cloth will retain enough moisture to germinate the seed in a few days in 20-32-degree C temperatures. The seed contains an adequate food supply for germination. Prevent fungal attacks by watering with a mild two-percent bleach or fungicide solution. Once seeds have sprouted and the white sprout is visible, carefully pick up the fragile sprouts (with tweezers) and plant them in a pre-drilled hole in the rockwool or Jiffy cube. Take care not to expose the tender rootlet to prolonged intense light or air. Cover the germinated seed with one centimeter of growing medium and keep the white root tip pointing down.
Transplant grow cubes into hydro clay when roots are visible outside the cube. To transplant, simply set the cubes into hydro clay. Bury deep enough to cover the blocks. Water by hand with nutrient solution until roots penetrate the hydro clay and can be irrigated automatically.
There are many outstanding hydroponic fertilizers available – General Hydroponics, Canna, Ionic, Dutch Nutrient Formula, Nutrilife, BioBiz, etc. These are a few of the companies that provide excellent technical support.