Hydroponic growing mediums are a crucial component in hydroponic systems. They provide the plant roots with an area to grow and take up nutrient solutions from the water solution.
A wide variety of growing media can be used, but each has its own benefits and drawbacks. How do you choose the right one?
This post will examine what hydroponic growing mediums are available and why they’re essential. How to use them, and which ones work best for different types of plants and hydroponics systems.
The Importance Of Choosing The Right Growing Medium For Hydroponics?
When choosing hydroponic media for your growing plants, it’s essential to consider the plant’s size and shape. Some types are better suited for specific hydroponic systems than others, leading to you having false starts or wasting time with setups that don’t work well together.
Choosing a hydroponic medium depends on whether or not it will be reusable, such as Rockwool cubes. Or if some maintenance is required, such as perlite that needs topping up every so often to remain damp.
Growing media used in hydroponics include inorganic substances like sand, gravel, and growstones made of recycled glass, organic materials such as pine bark and coco coir, and even air.
You also need to consider how much room they’ll take up, their weight, and any requirements needed before use. This includes, for example, pH range which could affect the roots and the growth of microorganisms.
An important thing to consider is what they’re best suited for – you don’t want heavy growing media that will change how high your setup hangs or an overly light one if it’s supposed to be filled with water.
The following are the 14 most popular growing media and how they do in various hydro systems:
1. Coconut Coir
Coco coir, or coconut peat, coconut fiber, or coco chips, is a wildly popular growing media for hydroponics. It is a byproduct of the coconut industry and is made out of the husk of coconuts. Coconut husks would go to waste or be composted if not used in hydroponic applications.
Coco coir is a natural, organic growing media that has an excellent ability to absorb water and nutrient solutions for your hydroponically grown plants. It’s pH-neutral, which means it will not affect nutrient levels and have excellent water drainage properties.
How to use it?
Coconut coir is a very lightweight growing media, so it’s best to use 50% in your mix.
It has good drainage but can be challenging for the roots of shallow-rooted plants growing hydroponically, like tomatoes or cucumbers. To help with this problem, you may want to add clay pellets to increase water retention and retention of fertilizer.
Using coconut coir for hydroponic systems with a constant higher temperature is not advised. It may decompose too quickly and become acidic, which can be toxic to your plants.
Add the coco fiber in layers to the bottom of your container until you reach about two inches from the top. Then fill up as much air space as possible with water so that there are just small pockets between dirt and water level. The wetter, the better!
What system does coconut coir work with?
Coconut coir can be used in drip systems, wick systems, ebb and flow (also known as flood and drain systems).
Benefits:
- easy to find and relatively inexpensive
- Excellent water retention and aeration
- Coco peat can help prevent root rot
- pH-neutral
- Organic material and environmentally friendly
Downsides:
- Holds water and may drown plants
- Salt build-up
- it can rot if not fully submerged in water or kept moist enough.
Read more on our in-depth guide on coconut coir.
2. Perlite
Perlite is an extremely lightweight and porous medium that makes it perfect for wicking cultures. It’ll let oxygen pass through easily while still holding plenty of water. It has one of the best oxygen retention levels of all hydroponic mediums. It is made from hardened volcanic rock and can be found in a variety of different media sizes.
How to use it?
Perlite works as a secondary media for wicking hydro systems because of its porous nature, allowing plant waste to drain quickly away from root zones. You must mix it with another hydroponic grow medium (like vermicule, coco coir, or soil) in equal quantity (50-50) to give plant roots a place to anchor down.
What system does perlite work with?
Perlite is suitable for many styles of hydroponic gardening, such as the following setups:
- Drip irrigation systems
- water culture systems
- Wick system
Benefits:
- Inexpensive
- Reusable
- Air holding
- Affordable
- Sterile / PH neutral
Downsides:
- It falls out of place if not secured in some way
- Potential particle inhalation danger
- Root blockage
- Environmental concerns
Read about vermiculite vs. perlite here.
3. Rockwool
Originally made in a lab for industrial purposes, Rockwool is an excellent hydroponic growing media. Rockwool is a loose-fiber material that starts as rock, spun into fragile and long fibers like fiberglass. Then these fibers are pressed into cubes of varying sizes.
You should know that rockwool usually comes at a high pH and need soaking.
How to use it?
Rockwool hydroponic growers find it the perfect media for high-density growing due to its excellent airflow and ability to hold water. It’s light weight, so it won’t weigh down your plants or cause problems when harvesting them from a vertical grow setup.
The process of spinning and compressing fibers can create a cloud of harmful dust that may harm your nose, lungs, and eyes. You can prevent it by immediately soaking Rockwool in water once you take it out of the package. Because of these downsides, Rockwool is rapidly being replaced by starter plugs as a reliable way to get seeds sprouting.
What system does rockwool work with?
It can be used in almost any system:
- drip systems
- ebb and flow
- water culture systems
- nutrient film technique systems.
Benefits:
- Excellent at holding onto moisture
- Fiberglass texture allows plant roots access without slowing their growth rate
- Easy to install in vertical garden setups
Downsides:
- Not biodegradable – must be composted after use if not bought pre-composed
- potential particle inhalation danger
- Environmental concerns
- It can be expensive and difficult to find locally
- High PH
4. Expanded Clay Pellets
Clay pellets, also called clay pebbles or lightweight expanded clay aggregate, are the most common growing media. Expanded clay pellets are made up of crushed clay and then fired to create small, lightweight pieces for easy use when installing your hydroponics system.
How To Use It?
When installing your hydroponics system, you will need to pack the expanded clay pellets between a mesh netting with some form of plant support. It can be used independently but is more subject to moisture retention issues.
What system do expanded clay pellets work with?
Lightweight expanded clay aggregate can be used in any system, making it the most versatile of any hydroponic media. However, this medium is most suited for the following hydroponic setups:
- Ebb and flow systems
- DWC systems
- Drip irrigation systems
Benefits:
- Absorbent and lightweight pebbles
- Environmentally friendly
- Good ventilation for the root system
- Deters pests
- neutral PH
Downsides:
- Must be soaked for effective use
- Wrong choice for cold climates
- Poor moisture retention
- Heavyweight when soaked in water
- Must be properly cleaned
Read more on our in-depth guide on clay pebbles.
5. Oasis Cubes
Oasis cubes are a hydroponic growing medium that is made from water-soluble and water-absorbent polymers. If you have ever received a bouquet of flowers that have been wrapped in a green foam-like substance, then you know what oasis cubes are like.
They provide plant roots with oxygen while keeping them well-hydrated.
Oasis cubes come in many different sizes, from ½ inch all the way through 8 cubic inches. They will accommodate any plant’s water needs no matter what it needs to survive each stage during the growth cycle.
How To Use It?
Place the oasis cubes in your growing tray or potting mix and moisten them. Add water to your hydroponic system until it reaches a level that is about three inches deep.
What system do oasis cubes work with?
They fit well with all different types of hydroponic grow systems.
Benefits:
- Excellent to start seeds or propagate cuttings
- neutral pH
- no pre-soaking needed
- Water retention of 30 – 40 times their own weight.
- Accelerates germination
- Enhances root development in the early stages of the plant’s life cycle
Downsides:
- Not eco-friendly, they are very similar to Styrofoam in this manner.
- Although they are reusable, the initial cost is relatively high.
6. Rice Hulls
Rice hulls are most often used in hydroponic growing systems that require a more significant amount of space because they are lightweight and easy to handle.
How To Use It?
Rice hulls decomposition happens quickly, so you’ll have plant roots growing right up into the material itself. This could lead to root rot over time if not removed promptly. The best rule of thumb is replacing it once every four months or sooner, depending on how much of a visible nutrient and root matrix is present.
Keep in mind not to use fresh rice hulls because they are not sterilized, and there are risks of microorganisms, decaying bugs, and weed seeds.
What system do rice hulls work with?
Rice hulls can be used in many hydroponic growing systems, but they are best suited for the deep water culture method.
Benefits:
- Less expensive than other types of hydroponics growing media
- Organic material
Downsides:
- Rice hulls decompose over time.
- Do not provide any significant nutrients for the plants and will need to be mixed with another type of growing medium.
- Not PH neutral
7. Sand
Sand is an excellent growing medium for hydroponics because it is well-draining and provides good air circulation. This type of growing media is also one of the most affordable types to use. It can be purchased in bulk at a lower price per pound than other growing media, such as rock wool or coco coir.
How To Use It?
If your grow room is small, it may make sense to use something healthier than sand because of its high evaporation rate. Mixing with other mediums can help combat this issue by adding nutrient solutions and increasing water retention properties. Different growing media will have different pH levels, so only mix them if they are similar values.
What systems is sand best for?
Sand is best for hydroponic systems such as the DWC or ebb and flow.
Benefits:
- One of the cheapest hydroponic growing mediums (or even free).
- A good option for thicker plants such as tomatoes or squash that need more stability and support
- Sand provides a balance between airflow in your system and water retention, which reduces root rot while still providing ample oxygen to roots.
Downsides:
- Low aeration
- wet sand can get stuck together, causing “sand clumps.”
- tends to dry out quickly when used alone and needs frequent watering
8. Wood Chips
Wood chips are a more expensive option than other growing mediums. Still, they provide good, organic nutrients and protection for plants.
How to use it:
– Use wood chips in hydroponic systems with larger plant environments. Soak for a day before adding to your system
– Works well when mixed with other hydroponic media
What systems are wood chips best for?
Works well with DWC or ebb and flow
Benefits:
- retains water well
- Totally organic
Downsides:
- difficult to evenly distribute the growing media because of its weight
- if you want to change out the water or adjust pH levels often, this can be an issue.
- Needs frequent watering
- causes Protein Buildup on the Bottom of the System, which can Slow down Plant Growth (especially if not mixed)
- May bring fungi, pests
9. Vermiculite
Vermiculite is another lightweight growing medium, and, like perlite, it also helps maintain stable humidity levels.
It’s a good option for space-conscious hydroponic growers as well because of the dry weight ratio. On the other hand, vermiculite is made of a mineral that can absorb more water than rockwool.
It also provides excellent drainage and doesn’t wick up moisture from below.
How To Use It?
You can use vermiculite as a stand-alone growing medium or mixed with perlite. Just as with rockwool, vermiculite should be moistened before you use it.
Vermiculite retains water quickly. You should either soak it before use or cover it with another growing medium on top to prevent the plant roots from sitting in wet vermiculite for too long.
It’s also worth adding extra perlite when mixing vermiculite with other hydroponic growing media.
What systems are vermiculite best for?
A trendy medium for drip type hydroponic systems as well as the ebb and flow systems
Benefits:
- Vermiculite is a more natural option for organic gardeners
- It’s not as expensive as some others
- Takes longer to break down
Downsides:
- it needs to be hydrated before use, so your system or you’ll have an icky mess.
- Poor drainage capacity
- A danger of suffocating plants
10. Peat Moss
Peat moss is an organic material that can be found in many areas and on the cheap. The downside is that peat moss holds onto gases from fertilizers very quickly. If there are any problems with excess nutrients, this could lead to toxicity in plants over time!
How to use it?
Using peat moss is relatively easy. It doesn’t need much mixing with other hydroponic growing mediums and is suitable for any type of system.
Peat Moss can be used in any soilless system that uses water as its nutrient delivery system and relies heavily on the hydroponic growers to manage the pH-balanced water.
What systems is peat moss best for?
Peat moss is excellent in ebb & flow systems and topped up regularly – like aeroponics or deep water culture. It does not work well in NFT systems where the nutrient solution falls straight onto the growing media. That’s because peat moss needs to be wetted before this happens, so over-watering may occur if you don’t care when topping up!
Benefits:
- very stable and has a neutral pH
- It can hold up to four times its weight in water, which means you need less growing medium than other options!
Downside:
- Can grow plants that love acidic soil (e.g., potatoes) because they may struggle in an alkaline environment.
- Not renewable
- Relatively expensive
11. Starter plugs
Starter plugs are a great option if you’re just starting out and don’t have much money to spend. It’s made up of organic compost and doesn’t break apart like soil due to a biodegradable binding material.
Starter plugs are a great way to get started, and you can usually find them at your local hardware store or nursery. They’re a one-time purchase that will last you a while!
How to use it?
Using starter plugs should be easy. Just cut off the top part of a starter plug, then plant your seeds or seedlings in it and keep an eye on them to make sure they’re doing ok.
You cut off the top part of the plug and then place it into the water until it expands enough to cover up all but about an inch of dirt and let your seeds or seedlings growing there.
What systems are starter plugs best for?
You can use starter plugs with any type of hydroponic system.
Benefits:
Starter plugs are an easy and inexpensive way to start growing hydroponics. They can be used with any system type. They’re suitable for smaller plants like cucumbers because of their size.
Downsides:
You have to cut them into pieces every time you want a plant, or it will get
If you don’t have much room for plants, these plugs might not work well for you because they take up more space than other hydroponic growing media options. And if possible, try to pick shapes closest to your plant’s needs when it gets bigger! That way, there’s no wasted space – like with tomatoes vs. cucumbers.
12. Growstones
Growstones are a great option because they’re made of natural minerals, so they don’t release any pollutants. They are great in hydroponics because they can take up to four times the organic matter as other growing media.
Grow rocks are safe to use in hydroponics, and the nutrients and minerals will be directed right where your plant needs them.
If you want an organic option or something good at supporting plants’ root growth, grow rock might be an excellent choice for you!
How to use it?
Just add the grow stones to your growing tray and then put water on top of them. The more you use, the better it will drain out when the watering time comes around!
When it’s not in use for production purposes, they can be used as decoration or just plain old gardening rocks – so versatile!
Ensure you use less than other types of growing media if you want to minimize the nutrient build-up.
What systems are growstones best for?
A common choice for Ebb and Flow system.
Benefits:
- This is an excellent growing medium for plants that are on the smaller side
- natural and biodegradable, so it’s easy on the environment!
Downsides:
- If you don’t have much room for plants, these plugs might not work well for you because they take up more space than other media for hydroponics.
- And if possible, try to pick shapes closest to your plant’s needs when it gets bigger! That way, there’s no wasted space – like with tomatoes vs. cucumbers.
- lack of nutrients – you’ll have to add additional supplements or fertilizers to keep your plant healthy long-term
13. Pumice
Pumice is very popular for hydro growing because they’re lightweight, porous, slow to break down, and hold the air well because of spaces between each particle. This makes it great to use as an aeration help – just be careful not to let your plants dry out too much!
Pumice has good water retention but not as good as vermiculite, which is also a mined mineral.
How To Use It?
Make sure that there’s enough room between them and the edges or sides of the growing container. If not, plant roots could become damaged from being squished against these surfaces too hard.
Do not place pumice rock directly under your pots or trays – they will end up sitting in stagnant water, which can lead to root rot, fungus growth, and other nasty things!
What systems is pumice best for?
Pumice can be used in most hydro systems, like NFT or Ebb & Flow.
If you’re using pumice in hydroton pellets that are just placed into a container, don’t forget to add holes so the water can flow through more quickly.
Benefits:
- lightweight
- Excellent water holding capacity
Downsides:
- Lightweight for some hydroponic system
14. Sawdust
Sawdust is usually a mix of different types, but they all have one thing in common: bark. It can be made out of pine or fir trees that come from sustainable forestry practices, so you’re not leaving any environmental footprint behind when harvesting this material!
Bark provides an excellent balance between aeration and water retention for your plant’s roots to grow through.
Best suited for: beginner gardeners or hobbyists; those looking for sustainable materials (sustainable forestry); those not wanting much maintenance involved in maintaining their plants’ health after planting them in the ground once they’ve reached maturity!
How To Use It?
Using sawdust is simple. Just mix in some with your potting soil and add it to your container like any other hydroponic media.
This makes this hydroponic growing media an excellent choice for beginners who need an easy way into gardening!
What systems are sawdust best for?
Because it is a great hydroponic growing medium for beginner gardeners, sawdust can be used in all hydroponic systems.
However, this material may not work well with larger plants or those requiring high amounts of water due to its ability to retain moisture.
Benefits:
- biodegradability at an acceptable rate
- low superficial specific gravity
- high porosity
- high water retention
- moderate drainage and high bacterial tolerance
Downside:
- PH-altering, and can be contaminated.
- It may not be sterile
- Root rot over time
Conclusion
In conclusion, when selecting your hydroponic growing media, you have many options available for whichever type of setup you use. The type you choose will depend on the system, your personal preference, and often cost.
In this article, we talked about some of these options in detail, hopefully giving you a better understanding of what is out there and how to use it.
Thank you, and happy growing.
