Hydroponic growing isn’t new.
The earliest records of hydroponics date back to ancient civilizations thousands of years ago.
But it’s a totally different ballgame now.
Today’s growers have a wider range of growing media to choose from as opposed to just water or sand.
- What are the best hydroponic growing media?
- How do you choose the right one for you?
That’s what we’re here to answer.
Why Your Growing Medium Matters
In the simplest terms, the growing medium you choose is as vital as the hydroponic system you choose.
Let me explain.
- Your medium must be able to provide the oxygen and moisture levels required by a specific plant. When you wet the media with nutrients, it must transfer these nutrients to the roots.
- If your plant has fragile roots, the medium must be light enough to avoid causing damage and to ensure upright growth.
- Your growing medium is an important part of pest control. For some, a medium that keeps away pests and weed may be a priority, in which case inert media like perlite is recommended. Inert materials don’t attract typical soil-borne pests and diseases, providing growers with healthier plants.
What To Consider When Choosing The Best Growing Medium
Each medium has its own advantages and is better suited for specific plants and hydroponic systems. It pays to check out all available options at hand and find the medium that most suits your purpose and intentions.
When making your decision, you must consider a range of factors:
- Type of plants you want to grow
- Your budget
- Availability of said medium
- The hydroponic system you plan to implement
However, your end goal remains the same. Your plant must have the proper moisture.
- Too little moisture and the plant dies.
- Too much moisture leads to root rot.
Hardly a surprise!
It’s a lot to take in, but our guide will make things much easier.
13 Best Hydroponic Growing Media (Pros, Cons & Where To Find Them)
Ready to get started? Here are the 13 best hydroponic growing media discussed in this guide:
- Coco Coir
- Hydroton Expanded Clay Pebbles
- Oasis Cubes
- Rice Hulls
- Polystyrene Packing Peanuts
- Wood Fiber
Let’s get started.
1. Coco Coir
Made from the husk of coconuts, coco coir is a surprisingly efficient growing medium that has been rapidly gaining popularity in the hydroponics community.
Why is that? Well, for starters, it’s a renewable material made from a byproduct that’s generally discarded. Second, it has a high air-to-water ratio that keeps roots from drowning while staying aerated. The larger the coco coir, the larger the air pockets.
The medium plays very well with roots and is versatile enough to be mixed with other ingredients should you want a customized mix.
Benefits of Coco Coir
- Encourages fast root development by retaining water and nutrients
- Sustainable medium that uses a byproduct that would otherwise be discarded
- Not favored by pests (unlike soil) so doesn’t attract pests and pathogens
Drawbacks of Coco Coir
- Since it’s an inert medium, nutrients must be added and pH levels constantly monitored
- Plants grown in coco coir need Cal-Mag supplements
- (Maybe) High salt content. Research how the coco coir you bought is produced. If it was washed with salt water, confirm if the salt was rinsed before packaging. If not, you may have to do it.
Where to Buy Coco Coir
Those little specks of white you see in your standard potting mix? That’s perlite. It’s an inorganic medium manufactured from volcanic glass that has great aeration. It’s arguably the best medium of all for oxygen retention but performs woefully at retaining water, often floating when used as a standalone medium. It isn’t recommended for use in systems like an ebb and flow system.
However, a standalone perlite medium has almost no cation exchange, making it a great fit for long-term crops, particularly in drain-to-waste situations.
Benefits of Perlite
- Porous cavities hold nutrients and oxygen
- Can be reused after washing
- Inert pest-free substance ideal for starting seeds
- Little chance of root rot or damping
- Air pockets resolve any anaerobic zones present in the hydroponics system
Drawbacks of Perlite
- Since perlite holds little water in its cavities, moisture deficiencies are a real concern
- Dry perlite particles are dangerous if inhaled
- Perlite mining is an environmental concern
- Too lightweight for certain hydroponic systems
Where to Buy Perlite
A highly absorbent and airy medium, vermiculite is a form of hydrated laminar and closely resembling mica in appearance.
Vermiculite is a great medium for most growers. It’s extremely lightweight, making it perfect for growing seedlings and plants with delicate roots, and its sterile composition doesn’t attract pests and insects. It’s also non-toxic and has a neutral pH. Unfortunately, its high water retention means there’s a risk of suffocating your plants.
It’s similar to perlite in many ways with the key differences being vermiculite’s superior water retention and subpar aeration. The two are often mixed since they complement each other very well.
Our Perlite vs Vermiculite comparison dives deeper into these popular hydroponic growing media.
Benefits of Vermiculite
- Holds water very well
- Suitable for propagating cuttings and starting seeds
- A straight vermiculite medium prevents plant health problems like root rot and damping
Drawbacks of Vermiculite
- Aeration capacities aren’t as good as perlite
- Extremely high water retention, which can suffocate plants
Where to Buy Vermiculite
4. Hydroton Expanded Clay Pebbles
Clay balls, Hydroton grow rocks, leca clay…this growing medium is known by many names. Whatever you decide to call it, it’s certainly one of the most versatile growing media on this list of the 13 best hydroponic growing media.
Hydroton clay pebbles have skyrocketed in popularity in recent years, mostly thanks to their ability to retain high levels of water, oxygen, and nutrients.
This is made possible by the porous shape of the particles. These features make Hydroton clay pebbles suitable for a range of hydroponics setups. You can use it as a standalone growing medium or mix it with soil and other growing media.
Due to the ease in harvesting and transplanting, Hydroton clay pebbles are favored by small scale producers using Dutch bucket or media bed techniques.
Benefits of Hydroton Expanded Clay Pebbles
- Drains excess water while retaining just enough for a constant supply of nutrients
- Doesn’t attract bacteria and insects due to its sterile composition
- pH neutral
Drawbacks of Hydroton Expanded Clay Pebbles
- Can be expensive for small-time growers and hobbyists
- May hold too little water, causing roots to dry out
- Must be cleaned before use as the dust can block drainage pipes
Where to Buy Hydroton Expanded Clay Pebbles
Rockwool has been used for decades, especially on the commercial side of hydroponics.
Made of limestone and/or granite, this porous medium is immune to microbes and offers good air and water retention. This prevents dehydration while providing continuous oxygen to your plants.
It ticks all the boxes a grower may be looking for but brings some steep disadvantages. Rockwool isn’t biodegradable and will last forever once discarded while the dust and fibers from the material can be dangerous if inhaled. Similar to asbestos, these particles can sometimes stick to the insides of the lungs.
The manufacturing process isn’t exactly environmentally friendly either while its naturally high pH levels give you a new concern right out of the box. Due to these issues, Rockwool is being replaced by more sustainable and safer alternatives.
If you intend to use Rockwool, masks, gloves, and goggles are a must.
Benefits of Rockwool
- Great aeration and water retention
- Easy to customize the size for your requirements
- Doesn’t degrade or break down over time
Drawbacks of Rockwool
- Potential health hazard if inhaled
- Doesn’t degrade naturally, so isn’t environmentally sustainable
- Treating required due to the naturally high pH levels
Where to Buy Rockwool
6. Oasis Cubes
Ever receive flowers in a weird green foam substance? If so, you’ve already come across oasis cubes. They’re very similar to Rockwool and are manufactured from phenolic foam, a water-absorbent material.
Oasis cubes are specially designed to serve as a great initial environment for plant cuttings and seedlings. They’re lightweight and pre-formed with tiny capillaries that enable better water and oxygen retention. Each cube contains the exact level of nutrients and water required for the growth of the plant.
The use of oasis cubes doesn’t extend beyond the initial germination phase because they aren’t a suitable medium for a full-grown plant.
They’re widely used in the commercial space for seed propagation and rapid germination of crops like cole crops, lettuce, or onions. They’re also very popular in the floral industry for both perennials and annuals.
Benefits of Oasis Cubes
- Specially designed for seed germination and propagating cuttings
- Neutral pH
- Accelerates germination
- Good water retention
- Encourages early root development
- Pre-soaking isn’t required
Drawbacks of Oasis Cubes
- Reusable but the initial cost is high
- Not a sustainable material
- Use is restricted to germination only
Where to Buy Oasis Cubes?
Manufactured from glass, Growstones are irregularly shaped, lightweight, and dust-free. A common worry with Growstones is concern over glass cuts, but this is an unfounded fear. The glass is crushed, melted, and sometimes mixed with calcium carbonates so there’s nothing to worry about.
This inert growing medium can hold close to equal amounts of air and water, and since it’s made of glass, it isn’t toxic or attractive to pathogens.
In addition to its wide range of benefits, Growstones are completely eco-friendly because they’re made of recycled glass.
Benefits of Growstones
- Porous surface improves drainage and aeration
- Growstones are dry so there’s no possibility of root rot, waterlogging, or fungal disease
- Great wicking abilities, able to draw moisture up to 15 cm above the water line
Drawbacks of Growstones
- Coated in a fine layer of silica that must be removed and dusted in a ventilated space
- Clings to roots and may cause root damage
- pH levels need constant monitoring
- More expensive than other growing media
Where to Buy Growstones
8. Rice Hulls
A byproduct of rice milling, rice hulls have found new life as a hydroponic medium, a far call from the trash bin.
Rice hulls are the tough outer layer in the rice grain. Don’t confuse them with rice bran, which is milled later during the production of white rice. They hold little nutritional value but drain well and last a long time, making them ideal for hydroponics. Rice hulls are highly resistant to water but facilitate great airflow.
However, they aren’t pH neutral. (The pH level ranges between 5.8-7.2.)
Note: Don’t use fresh rice hulls. Since they aren’t sterilized, there’s always the risk of bugs, microorganisms, and weed seeds.
Benefits of Rice Hulls
- Improved aeration and nutrient retention
- Cheap alternative to perlite
- Eco-friendly byproduct that would otherwise be discarded
- Must be soaked in water for at least a day to prevent fermentation or seed growing
- High water resistance
Where to Buy Rice Hulls?
Pumice is a readily available and inexpensive growing medium. Manufactured from volcanic rock, this porous material does a great job of holding nutrients, giving growers better control over watering cycles, which is crucial for preventing algae growth.
Its water retention isn’t as good as vermiculite, but it drains better and prevents roots from drowning. Pumice is lightweight, durable, and slow to break.
The color of pumice varies depending on the region’s minerals. White, pale yellow, and pale gray are some of the colors the material comes in. On the bright side, the light colors make pumice excellent for summer growing because it doesn’t hold onto heat.
Pumice draws many similarities to perlite, as both are mined and often mixed with a range of other growing media such as coco coir and vermiculite for improved features. In addition, the two are lightweight and will float if utilized in the wrong system.
Benefits of Pumice
- High retention of oxygen and water
- Slow to break down
- Excellent for summer growing because it doesn’t attract heat
Drawbacks of Pumice
- Can be too lightweight in smaller quantities
- Not pH neutral
- Not suitable for all hydroponic systems
Where to Buy Pumice
Sand is one of the oldest growing media for hydroponic systems and is said to be the medium used in the Hanging Gardens of Babylon, one of the earliest examples of a hydroponics system.
It’s very cheap or even free; you could scoop a bucketful at the local beach!
Sand is a good starting medium for those new to hydroponics but is very heavy and not suitable for delicate root systems. Needless to say, this will add to the weight of your hydroponic system. It also fares poorly in both aeration and moisture retention.
Benefits of Sand
- Cheap (or free depending on your region)
- Easily available
- Can be mixed with perlite, vermiculite, and other media for increased aeration
Drawbacks of Sand
- Very heavy and not suitable for delicate root systems
- Poor aeration
- Tiny sand particles can clog up your system
Where to Buy Sand?
Yup, it’s the same stuff you see in an aquarium. Similar to sand, gravel is easy to obtain and has been a popular growing medium for quite a while, especially in ebb and flow systems.
Because gravel is basically fragmented hard rock, there’s a large vacuum of space between particles. This space holds air and provides roots with a constant supply of oxygen. Conversely, this means water retention is poor and roots may dry out quickly.
Gravel is heavy and a gravel hydroponic system will be difficult to carry or move. Depending on your use, this could be a benefit because it creates a solid base. Gravel is also durable and can be reused after you rinse and sterilize it.
As with sand, gravel is a good medium to learn the ropes before moving to other materials.
Benefits of Gravel
- Inexpensive and easily sourceable
- Easy to clean
- Drains well
- Can be reused
Drawbacks of Gravel
- Gravel based systems are heavy
- Poor water retention makes gravel an unsuitable medium for water-loving plants
- Not compatible with all hydroponic systems
Where to Buy Gravel
12. Polystyrene Packing Peanuts
Packing peanuts have come a long way from simply protecting your belongings during transit. Today, they works as an excellent growing medium.
Polystyrene packing peanuts drain well and can be found everywhere. You probably have some lying around your place right now! Their extremely light weight makes packing peanuts unsuitable for outdoor gardening but perfectly fine for hydroponic systems.
Polystyrene packing peanuts are cheap but the synthetic material has no nutrients, so they provides zero value to the plant. Also, the material can absorb moisture and become waterlogged, resulting in compression. While one could find biodegradable packing peanuts, these break down into slush.
Lastly, you can’t ignore the environmental impact. Most growing media, like perlite or coco coir, decompose naturally over time and pose no threat to the environment. Polystyrene packing peanuts take millions of years to decompose and are a frequent contributor to ocean pollution.
Benefits of Polystyrene Packing Peanuts
- Discarded packaging peanuts can be reused
- Drains well
Drawbacks of Polystyrene Packing Peanuts
- Plants may absorb styrene so there’s always a contamination risk
- Only polystyrene can be used; biodegradable packing peanuts deteriorate into slush
- Not environmentally friendly
Where to Buy Polystyrene Packing Peanuts
13. Wood Fiber
Good old wood makes for an efficient growing medium for hydroponics. It comes from natural wood, so if you’re keen on following an environmentally sustainable lifestyle, this is an option to consider. Wood is a very popular medium in drip systems.
Of course, you must ensure your wood chips are sourced from uncontaminated wood and contain no additives. It’s highly recommended that you sterilize it before use. Similarly, if you opt for pine shavings, make sure they don’t contain chemical additives and are made from kiln-dried wood.
Another interesting feature is that studies have indicated that wood chips decrease the effect of growth regulators, meaning your plants may grow larger.
Note that wood, especially wood bark, uses up a lot of nitrogen as it decomposes and you may need to add more nitrogen to your nutrient solution to compensate for it.
Benefits of Wood Fiber
- Completely organic
- Doesn’t decompose easily
Drawbacks of Wood Fiber
- Attracts pests
- May not be sterile
- Consumes nitrogen intended for plants
Where to Buy Wood Fiber
13 Best Growing Media: Final Thoughts
No growing medium is universally better than the other. But for many growers, one medium may be a better fit than another.
Assess the factors that are important to you when making your decision.
Most importantly, consider the type of system you’re implementing. There’s no one-fit-for-all growing medium, but there are materials that are best suited for certain types of hydroponic systems. Your end goal is a medium where the roots are moist, not soggy, and overpowered.
If you have a favorite application for one of the 13 best hydroponic growing media listed above, let us know in the comments!