Soilless Mediums – Hydroponics substrates
Growing media definition
In absence of soil, different kind of soilless medium or hydroponics substrates are utilized by farmers to give their plants a sort of support. There are different kind of soilless mediums / hydroponic substrates which are used to grow plants hydroponically:
Polyurethane Grow Slabs
or also called Polyurethane foam growing medium it is the newest soilless medium developed specifically for hydroponics systems. It is sold in pre-cut cubes foam sheets. This media is composed of 80 percent air space and 15 percent water-holding capacity. This is the best balance in terms of air-water supply to our vegetable’s roots. Its super lightweight is also a plus for transportation. Furthermore, this kind of Hydroponic Sponge can be washed and re-used for several grow cycles. For all these reasons, we choose this soilless medium to grow vegetables hydroponically. We are proposing it also to our customers as the best and the cheapest hydroponic growing medium on the market.
Fibrous cubes made from melted rocks and minerals. Rockwool can hold enough water and retain sufficient air space (18-20 percent) to promote healthy root growth. It tends to have an higher PH value compared to other soilless medium. To solve this issue, you will have to soak it in water for at least 1 night before you can use it to grow your own vegetables hydroponically.
We didn’t choose rockwool as our favourite hydroponics substrates for 2 negative factors. Rockwool is not eco-friendly since it never truly decomposes. Furthermore, it’s also dangerous for our health. New rockwool blocks contain dust and fibres that can get in your eyes, mouth, skin and lungs.
is made from volcanic rocks. It’s often mixed with soil to increase aeration and draining. Vermiculite, which is used the same way as perlite and often mixed together, is made from heat expanded mica. Perlite and vermiculite are suggested only for starting seeds and cuttings.
We didn’t choose Perlite as our favourite soilless medium because it can’t retain water very well, which means it will dry out quickly between watering. On the other hand, we didn’t choose vermiculite neither because it retains too much water and can suffocate the plant’s roots. Furthermore, Perlite contain dust which can be bad for your health.
is not widely used today, due to its low water-retain capacity and weight. Furthermore, when sand is wet, tends to reduce the amount of air available to the roots, suffocating them.
is produced by crushing tough rocks such as limestone, sandstone or basalt. Gravel retain a good percentage of air but can’t hold any water. For this reason, vegetables’ roots can dry out too quickly. Another negative point regards its heavy weight.
also called coir, is the first “organic” medium.
Coconut fiber is a waste product of the coconut industry. It can maintain a larger oxygen capacity than rockwool yet also has superior water-holding ability. The main disadvantage of coconut fiber can be its high EC level. In fact, most of the coconut fibers producers, wash their products with salty water (during production). This can bring many issues in terms of nutrient solution EC control. The only solution is leaching with chemicals before use. This, obviously, produce pollution and let this medium “not so organic” anymore.
or even called Floral Foam. Oasis rooting cubes are rigid, open-celled, water-absorbing pieces of foam specifically designed for optimal callus and rapid root formation. Made from phenolic foam, oasis cubes are most often used for floriculture. This kind of Floral Foam has excellent water retain characteristics (over 40 times their weight). This can keep flowers fresh for long time for commercial purposes, but in hydroponics can be a disadvantage since can suffocate our vegetable’s roots.