A Farmer’s Guide to Substrates

Substrate use in greenhouses is on the rise and for good reasons.

Not only do substrates protect crops from diseases, but they also lead to an increase in production and a reduction in resource and labor use.

What are substrates?

Substrates are a growth medium used for crops. Rather than planting crops in regular soil, crops can be planted in substrates that are specifically designed to provide an optimal root environment. Farmers can use substrates of different sizes and shapes to make the most out of their greenhouse configuration.

The use of substrates first started to combat diseases in soil. When you plant and replant the same crops in the same soil, root diseases can easily spread and carry over to new seasons. Farmers can sterilize the ground between every planting, which can get expensive, or they can use substrates.

New substrates are used every planting season, ensuring there are no leftover fungi or bacteria that could harm future crops.

The advantages of substrates

Running a profitable greenhouse requires extreme optimization and efficiency. Substrates can help farmers by providing several benefits and advantages.

1. Increase yield: Crops grown on substrates tend to produce 20%-25% more crops. This is attributed to an improved root environment and minimal exposure to diseases.
2. Minimize loss: Farmers can lose up to 30% of fruit due to cracks and damage. Substrates minimize the amount of fruit loss because overall fruit quality is improved.
3. Reduce labor: Substrates are simple to refresh every planting season. Replacing substrates takes significantly less time than preparing old soil for new crops.
4. Improve control: Substrates provide a confined environment for crops’ roots. If you have a good system in place, you will have very tight control over this environment and can ensure perfect humidity and nutrients in the substrate.
5. Save water: Substrates can be closed systems with water recycling through the substrate. Rather than letting old water and salt drain, it can be recirculated through the substrate, saving about 30% of water usage.

The challenges with substrates

While substrates provide many advantages, they require very close control. While soil may be forgiving if you have a problem with your irrigation or drip systems, substrates are not. With soil, you might be able to wait a few hours or even a day to fix irrigation issues, but because substrates are more confined and compact, you need to fix any problems immediately.

Substrate types

There are different types of substrates that you can use in your greenhouse. While any sponge-like material that can absorb nutrients and allow roots to embed, these are the most popular materials for substrates:

• Stone wool/rock wool: This is an inorganic material made of stones. It is a reliable substrate made in factories and allows for very precise management of fertigation and irrigation. However, it can be difficult to maintain an optimum nutrient balance with it.
• Cocopeat: Cocopeat is an organic and eco-friendly material made of coconut husks. These husks function like wood, making a very stable root environment. This material can be reused after the crop for open fields as compost and to improve structure.
• Peat: Peat moss is an organic material made of decomposed plant material. Crops like peat moss, which gives them a very good start. A disadvantage with peat is that it starts to compost during the crop, which can destabilize the nutrients and cause root problems.
• Wood/sawdust: Wood fizzles or sawdust can be used for a substrate.
• Perlite: Perlite is volcanic stone with high oxygen content. It is inorganic and can be difficult to buffer nutrients inside it.

It’s important to note the differences between organic and inorganic substrates. If you use organic substrates such as cocopeat or peat, you can likely reuse the substrate at the end of the season for open field crops or for generator fuel. While you cannot reuse the substrate in your greenhouse, it can be a great growth medium in an open field once you remove the plastic covering. Inorganic substrates are non-compostable and not reusable. They usually can be recycled back at the factory where they were created.

How to start using substrates in your greenhouse

Using substrates in your greenhouse will have a huge effect on your efficiency, however, you must have the right system in place for it. If you want to succeed with substrates the first thing you must do is invest in a technical installation including backup irrigation, a facility for mixing nutrients, a reliable distribution system, and technical dripper lines. Your system should have alarms in place so you will be instantly notified of any issues.

Investing in a technical system might seem like a big expense, however, it will hugely pay off. This is the cheapest and most efficient way to improve production.

Next, you should figure out which substrate material you would like to use. To do this, you must first analyze the availability and prices of the different materials in your country. For example, cocopeat often comes from India, Sri Lanka, or Indonesia. Could you bring this material to your greenhouse cost-efficiently? Stone wool, on the other hand, is made in a factory. Is there a local factory you can purchase it from?

You must also consider which types of materials your crops might prefer in your environment. For example, if you live in a warm country, a substrate with larger water and nutrient buffer might be better.

In colder countries, you can probably get away with a lower buffer. If you grow cucumbers, you might investigate substrates with higher oxygen content like perlite, or if you’re growing peppers, you might choose a more water-soluble substrate.

In this analysis, you can also speak with other greenhouse growers in your area to see what they are using. Most likely, they have done their own analysis of what is available and what works in your environment.

Once you’ve done this analysis, it’s time to perform your own substrate trials. Install substrates in your greenhouse and start planting. Don’t be afraid to invest in larger buffers than you think you need. While you could probably get away with smaller buffers, larger buffers could pay off, especially when you are starting out. Larger buffers allow for more root volume, which is important if there are any issues with your irrigation or nutrient dispenser systems.

You can grow any crop in any substrate if you do it correctly. It might take you some time to learn, but substrates are a surefire way to improve results in your greenhouse business.

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Mr. Peter Klapwijk is currently delving into R&D. In the past, his work was very practical, and he helped so many companies. He thoroughly enjoys working with Paskal and all their latest innovative developments while always trying to keep it simple.

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