Hydroponic gardening is an easy and quick way to grow your own plants indoors, but you don't have to carve out a whole corner of your house to do it. Making your own hydroponic greenhouse is easy and can be kept small to accommodate cramped spaces or apartment living. Hydroponic gardener Pam Johnson with Taos Hydroponic and Organic Gardening Supply in Taos, New Mexico, has demonstrated how easy it is to build a small hydroponic greenhouse.
Place the rockwool bricks or mat into the propagation tray and arrange them so the holes are facing upward. Soak the bricks overnight in water to prepare them for the seeds. You will be planting the seeds directly into the rockwool bricks. According to rockwool manufacturer Grodan, rockwool is made from super-heated volcanic rock that is spun into fiber similar to insulation. Because it is made from the kind of minerals plants have to search for in soil, you will not need to feed or water your seed for a couple of days.
Plant a couple of seeds into the holes in each brick or into the holes in the mat.
Cover with the humidome and place the tray in a sunny spot or windowsill. Depending on the type of seeds planted, you could have seedlings in as little as a few days or a week.
By the third day from soaking, water your seedlings and add food. Any all-purpose organic plant food would work, but Johnson recommends researching the sorts of minerals your specific plants like for optimum results. If using a concentrated liquid feed, be sure to follow dilution ratios according to instruction.