Choosing a Hydroponic Substrate: Tips From the Pros

Why substrate is an important decision

Your growing substrate is a core element of your farm. It takes up space. It costs money. It requires labor. And it supports, both in the biological and the physical sense, your main product: your crops. Choosing the correct substrate can make your job easier and more profitable. Choosing the wrong substrate can cause speed bumps and set-backs.

Hydroponic substrates come both as aggregates and bound (or one-piece), and as artificial or natural media. They differ widely in particle or fiber size, amount of void space, percolation rate, weight, color, material, and degradability.

Luckily, information on individual hydroponic substrates is abundant, so the farmer’s decision is as easy as knowing what they need.

Okay, so maybe that’s not super easy. Knowing what your hydroponic system needs can be hard. To help you out,Dr. Nate, Chris Higgins, and TylerBarasfrom HortAmericas lent their experience and knowledge in choosing a hydroponicsubstrate.


Tip #1: Understandyourtechnique and process

Just because a medium is great for one grower doesnt mean that its great for another. Each medium acts differently, which means that when you choose a medium, you need to know what youll be using it for. Dr. Nate gives some examples:

Oasis: good for somethings like NFT production, bad for anything where it could be crushed. Rock wool: great for situations where its not compressed, where it will go anaerobic and choke out your roots. Polymer-bound plugs: Theyre very useful for systems where theyre compressed or handled heavily. hortamericas-riococo-coir-grow-bags.jpgCoco coir: loose media, like is great for systems where you dont worry about the medium breaking apart or washing through the system, but its really bad for systems where its going to be handled heavily. It depends on the type of medium.

*Growing seedlings and growing crops usually requires different substrates.

Tip #2:Ask the right questions about your process

To match a medium with your growing and selling processes, ask the right questions:

  • How much will I and my workers be handling the medium?
  • Will the medium compress in my equipment or through handling?
  • Does this medium work with automation? Do I need it to?
  • Where is my growing medium going after harvest? Will it be sent to the customer?
  • Will I be re-using the medium or disposing of it? Is disposal easy and ethical?

Tip #3: Estimate external costs

recycle-bin-trash-disposal.pngFarmer Tyler says, Many growers fail to see that a substrate’s value is not solely its price Choosing an option that has the lowest price might be ignoring the external costs associated with using that product like special germination requirements, additional labor, and disposal.

What external costs come along with the medium? Will it require special treatment at any point in your planting, growing, and harvesting process?

Tip #4: Account for the unique needs of vertical farming

Vertical hydroponics has unique requirements when it comes to a growing substrate.

Structure. Compaction is a risk in vertical systems, so a vertical system requires a medium with good structure.

Shear strength. A strong medium allows the vertical farmer to handle it easily without risk of crushing, tearing, or wearing it down. This helps with labor costs and with replacement costs.ZipGrow_Matrix_Media.png

In addition to these two unique needs, vertical hydroponic growers should be looking for a substrate with good aeration and high SSA. These needs leave you with two options: aeroponics and Matrix Media as your options.

Tip #5: Make a holistic decision

Once you’re familiar with the growing medium and how it will interact with your farm, combine all of your knowledge to make a decision.

A common mistake people make is focusing on just one factor (i.e. organic certification, price, size) when selecting a growing medium Make a holistic decision based on irrigation strategies, certification objectives, germination conditions, automatization goals, crop size, and price.

Horticulture supplies from the pros

Three weeks from now, we’re teaming up with Chris Higgins and Tyler Salas from horitculture supplies company, HortAmericas, to get you even more valuable information on hydroponic media.HORT-AMERICAS-LOGO-horizontal.jpg

We’re big fans of HortAmericas because they are helpful, work with the individual farmer, and they know their products.

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