Hydroponics is taking off as a significant space-saver and general improvement over traditional soil-based agriculture. It has numerous benefits over the old means of crop production, and there are several systems to learn and try out.
Many of these systems use a substrate for the plants to bind to, and there are even more substrates than there are hydroponics systems. So how do you know which one to use? The decision must consider your specific needs and the limitations of the system you’re using.
Keep reading for the benefits and drawbacks of some of the most popular substrates, and learn about why they matter!
Why Hydroponics?
Hydroponics is a means to grow plants that doesn’t involve the use of soil. Instead, it uses nutrient-rich water circulated across the plant’s root system. This water is adjusted to the plant’s specific needs.
Hydroponic growing has numerous benefits over traditional agriculture. Its popularity comes from the following benefits:
Uses less water – Hydroponics can use up to 92% less water over traditional growing techniques. This is because systems can be well-contained, and water can be recycled. Loss to evaporation is much more limited.
Grow any plant – By fine-tuning the nutrient content of the water, you can tailor it to the specific needs of the plant of your choice. This allows you to grow a wide variety of different plants in close proximity, without the need for specific soil types or qualities.
Better use of space – Because the hydroponics system is compact and contains everything plants need, it’s possible to grow a lot more plants in a small space. Further, because all the nutrients are supplied directly, plant roots don’t spread out and compete with their neighbors, meaning plants can be kept much closer together than in soil.
More efficient growth – This lack of root growth allows the plant to put more energy into foliage, flowering, or fruiting, resulting in much healthier crops and a larger harvest. The yield can be eight times as high as with traditional agriculture.
Cleaner produce – since removing soil also removes the soil-based pests, there’s a dramatic reduction in infections with hydroponic growing. Weeds are also easy to keep at bay, which results in less need for herbicides or pesticides.
Hydroponics systems are also easy to decentralize, keep organic, and to grow indoors, meaning you cut down on transport costs, expensive fertilizers and can grow all year-round.
These are just a few of the benefits of hydroponic agriculture, but if you’re looking to set up a system at home, you will need to know how to set it up and which substrate to use. There are countless tutorials and guides to setting up a hydroponic farm at home, but if you’re still puzzled by substrate types, we’ve got you covered.
What is a Hydroponics Substrate?
A hydroponic substrate is essentially a soilless growing medium. This is something that allows roots to bind, improves water retention, and maintains air pockets to maximize the health of the root systems of the plants.
Not all hydroponics systems need a substrate – some simply need something to support the plant, and water flow is continuous over the roots. Other systems use substrates to allow for a periodic nutrient flush to be used. These systems pump nutrient-rich water over the substrate now and again, and the substrate helps the plant hold onto this water and maintain hydration until the next cycle begins.
A hydroponics substrate can come in many forms. Some favor aeration, others have higher water retention. Some are eco-friendlier than others. The type of substrate – or whether you need a substrate at all – will depend on the type of system you’re using and the plant’s needs. There are several qualities of a hydroponic substrate that might be considered when choosing.
Qualities to Look for in a Hydroponic Substrate
Growers will have many substrates to choose from, but some of the most important characteristics to consider are drainage and aeration, durability, re-usability, weight, environmental impact, and pH.
Drainage and aeration are important for drip or ebb-and-flow systems, where water retention is a key factor. These qualities are found in absorbent substrates that do not compact.
A good substrate has strong durability and doesn’t crumble. The breakdown of the substrate can create unpleasant or even dangerous dust that can harm the plants or clog up the system, and substrates with low durability are also not reusable for as long.
Reusing substrate is a great way to save on costs, so it’s worth looking for something that can be cleaned up and repurposed after harvesting for the next generation of plants.
Sustainability should play a role in every financial decision we make, and choosing hydroponics over traditional agriculture, for some, is motivated by the desire to lower their environmental impact. In these cases, particularly, the nature of a hydroponics substrate’s manufacturing or supply process is worth taking into account.
Substrates ideally shouldn’t affect the pH of the system. Usually, they should be non-nutrient, chemically-inert beds for the roots; they should not contribute to the conditions of the water.
With these in mind, here are some of the most popular substrates:
The Most Popular Hydroponics Substrates
Rock Wool is commonly used for starting seedlings but works well for mature plants too. It’s formed in a similar way to fiberglass and has strong water retention and high levels of aeration.
It’s great for hydroponics systems that flush root systems with nutrients. It has a wide range of uses and is commonly used for herbs, flowers, and vegetables, including tomatoes and cucumbers. Drawbacks to this substrate include its cost and the fact that it isn’t environmentally friendly.
Coconut Coir is a by-product of coconut processing and is the biodegradable husk of the coconut itself. It provides a low-density, moisture-retaining bed for hydroponics systems and is relatively cheap.
Drainage and aeration are also good qualities of this substrate, and it particularly suits raised bed systems. While sustainable and easy to use, it retains a lot of phosphorous and not much carbon, so it isn’t suitable for all plants. Monstera and ferns do really well with this substrate.
Expanded Clay is made from superheated clay pellets. They are relatively large, robust particles meaning there is good draining and aeration, and they’re somewhat easy to reuse. On the other hand, they retain little water and can lead to dehydration if used in the wrong system. They’re also more expensive than the previous options. This is a versatile substrate, and many plant types do well with it.
Smart Gravel is one of the most convenient, eco-friendly substrates out there. Made by Arqlite from 100% recycled plastic, it’s inert, lightweight, pH neutral, and designed to solve many of the issues of expanded clay. Smart gravel offers excellent drainage and aeration. Its durable, produces no dust, and can be easily reused. The sticker price is more expensive than expanded clay, but the benefits and savings from having a dust-free, reusable medium far outweigh the increased price.
These are just a few examples of some of the popular substrates available – there are many more to investigate. Your choice will depend on the system you’re using and the plants you’re growing, as well as your personal preference.
Conclusion
Choosing a substrate doesn’t have to be difficult. Most of the popular substrates work well with a vast range of plants, and there are just a few key qualities to consider. Once you understand the plants’ drainage and water retention needs in your hydroponics system, you’re most of the way there.
Then it’s just a matter of taking into account cost, sustainability, pH, and convenience. All of these tend to fall on a spectrum, so the best way to find out is to experiment. Give some of these substrates a try and see which one is best for you!
