Mediums Matter
Now that we have your hydroponic garden up and running, it's time to focus on caring for your plants. Proper plant care is essential for healthy and productive yields, and there are several important factors to consider when growing plants hydroponically. In this chapter, we'll cover some of the key aspects of plant care in hydroponic gardening.
Hydroponic Growth Mediums
A growth medium gives support to roots as well as helps supply adequate oxygen to plants. The ideal medium holds just about as much air as water. Interstitial spaces; the area in between the fibers or granules of growth medium, are what determines the growth mediums’ air:water holding ability. It is important to adapt your medium to the particular type of hydroponic system that you intend to use. Fast-draining mediums are more beneficial for recirculating systems, whereas mediums that hold more water are better for systems that have a staggered watering schedule.
The most common mediums are:
Peat, Perlite, Rockwool, Expanded Clay Pellets (LECA), Coco Coir, and Gravel.
Coconut Coir (Coco Coir)
Made from the fibers of the coconut husk.
This growing medium consists of shredded coconut husks. It is both organic, and soil free. Coco coir is both a hormone-rich, and sterile growing medium to use for hydroponic cultivation. It will protect roots from disease and fungus and can be used in a variety of methods. The best part is that this is an eco-friendly option because coco coir is a completely renewable resource.
LECA
Made from expanded clay.
Expanded Clay Pellets are another great option for hydroponic growers looking for reusable mediums. It is coarse in nature and has much interstitial space in between each granule. These expanded clay pellets retain water due to the porous nature of clay. LECA is also PH balanced! Be sure to wash the clay pellets before incorporating them into your system, usually a bit of sediment will rinse off, much better than letting it clog your filters and pumps!
Perlite
Made from expanded volcanic glass.
The oldest of all soil free growing mediums, perlite is made from glass pellets that have been air puffed. It has excellent oxygen retention ability which is why it works so well as an aerator of hydroponic mediums. This is not however, the medium you would want to choose if you had a flood and drain system or those situated outside in the elements of Mother Nature (not in a controlled interior environment)
Peat Pellets
Made from compressed peat
These are composted peat plugs that are rehydrated by soaking them in water. They are available in a multitude of shapes and sizes and slightly resemble a sponge in texture and appearance. Peat pellets are used mainly for starting plants because of the fact that the pellets do not fall apart. This is perhaps the most crucial stage of the plant's development and starting off with a firm foundation makes a huge difference. Root damage that occurs during transplantation is the leading cause of transplant shock. The peat pellets usually have a nearly perfect air to water retention. These are ideal no matter what hydroponic system you intend to use.
Rockwool
Made by heating and spinning molten rock in a centrifuge, much like cotton candy!
This hydroponic medium is made from rock that has been melted into a molten state and then spun at high speed. It is much like the way cotton-candy is made, heat is used to elicit long glasslike fibers which are then compressed into bricks or sold loose. Rockwool also is known as a great insulator and was even used for a safe replacement of the fiberglass insulation common in most homes. Rockwool absorbs water readily and has wonderful drainage properties. Rockwool slabs can be used over again after a growth cycle, they are steam sanitized and put right back into use. Warning: many have found the dust and fibers of rockwool to be irritating to the skin. Be careful when you use rockwool, it is always advisable to wear a respirator, glasses and gloves whenever you are required to handle rockwool.
Gravel
Small stones that can be used as a growing medium in hydroponic systems.
Gravel is also used in hydroponic systems. It is recommended to use river gravel and ensure that it is thoroughly rinsed before adding it to your system. Gravel has excellent drainage properties but can retain relatively little water. Gravel should be used in recirculating systems (much like the application of LECA).
