I have seeded some Italian Grape tomato and spinach a couple of different ways. I directly placed some spinach into the right growbed about 1/2" below soil line. This is slightly above the water's max fill. I have also planted some spinach and tomato seeds into some 1"x1"x1" rockwool cubes. It has been only about 4 days since I seeded so I expect to see sprouts soon. I placed the cubes in direct sunlight beneath a window to help expedite the growth. According to my readings, spinach and tomato are supposed to do well in a frequently watered, hydroponic system. Spinach and tomatoes therefore seem better suited for my system than the carrots or onions did, of course I had to learn somehow.