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Substrate & Hydroponics: Best Practices With Water-Based Media

“It feels good at the end of the day to know you have made a product that other people are going to enjoy.”  ~ Jericho Sanchez


Farmers start with germinating and planting seeds, whether growing in soil or using a water-based solution. Most hydroponic farmers use heirloom or organic seeds in their farming practice and focus on organic certification or no spray techniques. This article aims to identify the most popular forms of growing media or substrate in water-based farming. Most importantly, it is the best use for each form of substrate that drives this conversation. I am also taking the opportunity to explore the uses of containerized water-based farms and their production abilities. 

Setting up a seed station or propagation area is vital; you’ll need a few items to start.  Starter plugs, net pots, heating mats, trays with transparent plastic hoods, tweezers, and grow lights.  This will get you going and ready to transplant to a larger platform with irrigation, pumps, and drainage. As you grow your business, scale, and ramp up, companies like Arictecture, AGrowTronics, The Aquaponic Source, and Verti-Gro offer equipment, guides by topic, and hydro-technologies to best run your company. 

Best Practices In Water-Based Media


In 2018, Shalini Kumari, from Bihar Agricultural University, saw a way to help India feed 1.5 billion people. So, he began his research in hydroponics, the historical aspects, nutrients, and material requirements for a successful hydroponic system. One of the most important is Growing Media, like Rockwool, gravel, sawdust, Perlite, sand, and vermiculite. He evaluated hydroponic media, or substrate, which offers the highest values for root stability and growth, water filtration, and total yields.  He found that a single substrate didn’t offer a silver bullet for growers; there are best practices derived from the substrate, distilled to yields by plant species.  

For example, Coconut husks allow for robust root growth and higher plant weight at harvest. Water-based strawberries grown in a combination of Coconut husks and Sawdust had a 17% higher yield and survival rate than other substrates. Using Rockwool to grow peppers allows for higher nutrient absorption and a larger size. Mixing substrates like coconut husk and Rockwool retain water and avoid root rot, growing and yielding some of the tastiest hydroponic tomatoes! Each substrate must be tested for salt content, limestone, and other minerals before use to help determine best practices when prepping our seed stations. I encourage sterilization or washing substrate before use, depending on the medium used. This research allows us to think through our budget design, which foods we grow, and how we build our system to sustain the long term. 

Coconut Coir/Husks

Coconut Coir/Husks

When coconut producers and food manufacturers manage their waste, they don’t let anything go to the landfill or get left behind, and coconut husks get compressed into bricks, discs, and potting mix for the nursery and hydroponics industries. Coir or Coconut husk is known for its excellent aeration and water-holding capacity. This product is also part of the Circular Business Model, where the waste of one product is evaluated and re-designed to serve a whole new purpose in the world. It's best used with garden vegetables, cucumbers, tomatoes, peppers, and squash. Some experts say this is an all-purpose substrate for any fruit or vegetable. It is a stable substrate for strawberries and other vines when mixed with Rockwool. 



Rockwool is made of Basalt, an abundant resource, and recycled Steel Slag, a byproduct of steel production. Combined, they are spun into a porous products like Rockwool for agriculture. I prefer Rockwool because of its porosity and ease of use when designing a hydroponic platform. It comes in so many forms that it's easily mixed with another substrate, remains stable, and allows for higher crop yields than most other substrates. Each slab contains different drainage qualities; the better the quality, the greater the precision of growing in large greenhouses and grow facilities. I highly recommend the starter cubes for more stable propagation and transfer to the production system, like a Tower Garden or Green Food Solutions, all in one system. 

Expanded Clay Aggregate 

Clay Aggregates

Clay aggregate comes in the form of tiny rounds, and to make them, they are baked in a kiln to provide strength, porosity, and lightness, offering good drainage.  Its ability to retain moisture is comparable to Rockwool, supporting the plant’s root system with integrity averting root damage. When running my classroom transferring the propagated seeds from the seed station to the tower, I would load a few in a Net Pot with the Rockwool to better manage water flow. 

Rice Hulls 

Rice Hulls

Like any other agricultural product, it is important to sterilize it or purchase it sterilized from the wholesaler. They are great for transferring starters to your production systems and must be soaked 24 hours before usage. They add nitrogen and are low-cost when just getting started in commercial production. Keep them wet, as they will cause mold and respiratory issues if they mold out. They have a shelf life of 2-3 weeks, maybe Rice Hulls are better for propagation than long-term growth cycles.


Perlite is a non-renewable resource made of aluminum silicate, mined all over the globe in places like Greece, New Mexico, Utah, Turkey, and China. Mixed with media like Peat Moss of Coconut husks, it becomes an excellent resource for growing squash, leafy greens, herbs, roses, and other floral products. Perlite allows for full oxygen saturation in plant life and is an excellent resource to be combined and increase drainage when necessary.

Peat Moss

Peat Moss is harvested from the dead layers of Sphagnum Moss beds, usually found in cold and wet places around the globe. These bogs are being looked at for environmental reasons, to help preserve the bog’s ecosystem and its 40,000 acres of natural resources. Peat Moss is a great resource, used in limited quantities, coupled with additional substrate to allow for better filtration and oxygenation.

The Future of Containerized Hydroponic Technologies

Leaf Greens Hydro

Imagine having the ability to grow on a continuous cycle, producing a 24x7 crop lifecycle in a fully enclosed, temperature and air-controlled system. What if we were to bring the fresh food product to Antarctica or the Prudhoe Bay production plants? Systems built to absorb and adapt to technologies where lighting and nutrient cycles grow food on a 45-90 day cycle. These containers have an output capacity of nearly 5.5 tons of leafy green products annually. The grow lights have high transfer of light efficiency, increase crop yields, and reduce electricity costs. These futuristic systems run in “Smart Farm” mode, secured in a 40-foot-long container, run by solar and wind systems.  Seeding, propagating, transplanting, vegetative, and harvesting stages all in one stable agricultural production pod. By making these systems more accessible to mainstream gardeners and agriculturists, this model could take community-supported agriculture (CSA) businesses to a new and different level. 

Root Balls with Net Pots

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