Plants need air just as much as they need water, and the key element to a successful grow medium is its ability to hold an abundant amount of oxygen as well as ample amounts of water.

In an NFT or aeroponics ystem, the watering and feeding of plants depend solely upon the flow of nutrient solution past the plants' roots. There is little if any grow media used. lIf water flow is interrupted, even for a short duration, plants quickly die. At the other extreme, if the root zone is continually flooded, roots suffocate of oxygen deprivation and plants quickly die. A good grow medium negotiates these extremes. Utilizing a grow medium maintains a reserve of nutrient solution in the root zone along with a percentage of air pore space.

Rockwool is great for example, because it provides an optimum buffering reservoir of nutrient while maintaining the volume of air in the root zone. The reserve of nutrient solution will be available even when the irrigation system is off for periods of time, or optimally, irrigation systems can be "pulsed" on/off to provide plants with that happy medium of air and water.

Rockwool is one of the most widely used growing mediums on the planet. Rockwool products are made basalt rocks and chalk, which is heated up to 1600°C, to create lava. The lava is blown into a spinning chamber, which makes fibers similar to cotton candy. The fibers are packed into mats, from which cubes, blocks and slabs are cut. The products make excellent use of natural resources - it is almost all based on recycled materials, often slag from primary preconsumer ferrous or nonferrous metals producers. One cubic yard of otherwise wasted rock becomes 37 cubic yards of rockwool.

Rockwool can be used to grow plants from propagation through harvest time. seeds or clones may be started in small rockwool cubes which can then be transplanted to larger cubes which can then be used on top of slabs. The cubes may also be transplanted for use with other mediums such as grow rocks.

We carry Grodan® Stonewool which when fully wet contains 80% solution, 15% air space and 5% fibers. This ratio of solution to air provides plenty of oxygen and vigorous root growth.

Totally biodegradeable and reuseable, rockwool should be conditioned for first use by soaking for eight hours in water at pH 5.0-5.5 and then rinsing with pH 7.0 water. To soak cubes, put them in a bucket filled with water. To soak slabs, cut a hole in the plastic bag they come in and fill it with water until totally saturated. After 24 hours, cut drainage slits in the bottom.

Although rockwool is nontoxic, when dry it can cause skin irritation. For this reason it is best handled wet. If irritation occurs, wash hands for instant relief. The fibers and dust from the dry rockwool are bad for your lungs. A dust mask should be worn to prevent problems

Rockwool can be used again for a harvest or two, and eventually it may be plowed into your garden - it will break up into chunks and add welcome aeration to the soil. (be sure to remove any plastic wrap first!)

Also known as grow rocks, expanded clay pellets are some of the most popular growing mediums availalbe. They can be a little expensive, but they are one of the only kinds of growing medium that can be used again and again with a minimum of breakdown. They are a great choice for the grower who plans on many harvests in the future. The brand we sell, Hydroton, is known worldwide for its superior quality.

Expanded clay provides excellent aeration as the odd shapes of the rocks allow for the formation of air pockets throughout the root zone. The inside of the pebbles are filled with air pockets as well and they are fairly light weight. The pebbles do not hold much water, so plants must be watered frequently to prevent roots from drying out. They are often used in Ebb and Flow systems. Expanded clay has a neutral pH and excellent capillary action.

When you purchase expanded clay, it will be a little dusty, and it is suggested that you rinse it before using it in your hydroponic system After you harvest your crop you can wash the rocks for reuse. The best way to do this is to remove as much of the plant matter as possibe and then soak the rocks in a 10% bleach and water mixture (one part bleach to 9 parts water.) You may also sterilize them using a mixture of Hydrogen Peroxide and water. (A few teaspoons of 35% food grade H202 per gallon of water.) Rinse the rocks very thoroughly and let the remaining chlorine or Hydrogen Peroxide dissipate over a few days (it will turn to a gas and leave the medium).

The major downside to this kind of medium is that a bag of grow rocks is pretty heavy and can be costly to ship.

Oasis Cubes are small rooting cubes that are similar to floral foam - the material flower designers use to hold floral arrangements in place. Completely pH neutral, Oasis cubes need simply be saturated with water (they hold 40 times their weight) and they are ready for use. They are xcellent for use in all types of propagation,including seeds and cuttings /clones.They have holes pre-punched in them. They come in sheets that fit in a standard black nursery tray.

The uniform cell structure of Oasis cubes assures proper drainage and water holding capacity for optimum air/water balance for your seedlings or clones.. The modest cation exchange capability of the cubes helps control availability of grower applied fertilizer.

Oasis cubes are often used as an alternative to rockwool starting cubes. They do have one negative problem. They are not compostable, they are not reusable and are just thrown in the trash at the end of the harvest.

Vermiculite is shiny, gold color flecks that can soak up to 3-4 times its volume in water. It’s sterile and attracts nutrients such as calcium, magnesium, potassium, and phosphorous. Vermiculite is the mineralogical name given to hydrated laminar magnesium-aluminum-ironsilicate, which you probably don't need to know. It resembles mica in appearance and is another volcanic silicate mineral. It's surface mined in places like Australia, China, Kenya, South Africa and the U.S. Unlike perlite, vermiculite is spongy. It's also super light and tailor-made for water absorption

A combination of perlite and vermiculite is a popular hydroponic medium. Perlite is hard and brittle, providing excellent drainage and root aeration. Vermiculite is soft and spongy, providing good water and nutrient retention. Perlite and vermiculite when mixed together in a ratio of 3:1, are an ideal medium for hand watering as together they hold plenty of moisture but still retains good drainage.

Soilless potting mixes are traditionally made from peat moss and then supplemented with perlite, vermiculite, micronutrients and and macronutrients. Today more options exist than just peat moss, and potting mixes are made from a variety of substances.

The soilless potting mix we carry, Ready-Gro is based a mixture or perlite and coir fibe, among a variety of other great organic additions. Coir fiber is a by-product of the coconut harvest and is a renewable resource. It holds 10 times its weight in water and does not shed water like peat moss. It holds and releases nutrients over extended periods. It is also said to provide xcellent aeration.