Rockwool is the most popular medium for germination seeds hydroponically. Loose, or granulated Rockwool can be placed in a standard plastic starting tray, and seeds are spread evenly spaced on top of the medium. The seeds are covered with a thin layer of Rockwool or Perlite and the tray is covered to prevent moisture loss. The loose Rockwool makes it easy thin, separate, and transplant seedlings. Even more popular than granulated Rockwool, are one inch Rockwool starting cubes. A flat containing 98 detachable cubes fits into a standard propagation tray. The Rockwool is soaked and pH balanced and one seed is placed into a 1/4 " deep hole provided in the centre of each cube. The seeds are then covered with a thin layer of Perlite or vermiculite and the lid is placed on the tray. Once the seeds have sprouted, the cubes are easily broken off and placed into larger growing cubes or other aggregate.

Another method of propagation is cloning, or asexual propagation. Stem cuttings from most types of plants can be rooted in seven to fourteen days, producing a plant which is an exact genetic duplication of the original, or "mother" plant. Plants started in this way will mature much earlier than ones started from seed, saving valuable time and producing shorter, bushier plants.

Depending on the type of plant, each mother could produce tens, or even hundreds of identical offspring every couple of months. Asexual propagation is an invaluable tool used for many commercial greenhouse crops, as well as for hobby gardens. Without question, the fastest and easiest way to root stem cuttings is hydroponically. Some methods incorporate extra aeration.

Air pumps or moistening devices provide stems with ample amounts of oxygen and water. Oxygen is vital to root development. The most common method used to root cuttings hydroponically is in one inch Rockwool cubes. The flat of cubes is pH balanced and soaked in a diluted, high phosphorus nutrient solution, then placed in a standard propagation tray. Using a clean, sharp blade, cut off a small branch consisting of a growing tip, two or three leaves, and 2" to 4" of stem.

As you take the clippings, let them stand in water until you have as many as you need. Before dipping in a rooting compound, make a fresh cut on each stem, just above the first cut. After dipping, insert the stem, about one inch deep into the rooting cube. Cover the tray with a clear plastic dome to retain humidity and give the plants 18 hours of diffused light per day. Remove the cover for a few minutes each day to give the plants fresh air and to avoid damping off. Mist the cuttings periodically with a mild foliar feed like kelp extract. To see if the clippings have rooted, give the stems a very gentle tug. The clones should be transplanted soon after roots have formed.