Hydroponic Growing Medium

If you want a hydroponic garden to be successful, in most cases, the nutrient solution will not be enough to give your plants the constant supply of nutrients they need; you will also need a growing medium.

A growing medium is a solid material, in the form of pebbles, sponge, fibers or shreds and bark that is used to withhold the nutrient solution (water and nutrients) and then release it slowly to the roots of the plants. But which ones are the tried and tested growing mediums, and how can you choose the best one for your hydroponic garden?

Using a growing medium has done to hydroponics what ‘Strawberry Fields Forever’ by the Beatles has done to pop music: it has revolutionized it.

But choosing the right growing medium is not easy, and you will need to know all the details of the different ones available and how they behave to choose the best one for your gardens and crops. 

Main qualities of a growing medium

We can’t use any solid as a hydroponic growing medium. It does need to have some basic qualities in order to be functional:

  • It must be inert; you cannot use materials that react with air or water (so anything that oxidizes, for example).
  • It needs to have a porous structure; the nutrient solution needs to penetrate the medium which then works as a “pantry”, a food and water reserve for your plants.
  • It needs to be penetrable by the roots; so, either foam-like materials, pebbles or fibers will be suitable for this function.
  • Ideally, it should also have a close to neutral pH; plants are very sensitive to soil pH, in fact, different pH levels result in different nutrient absorption rates. With a high pH, plants absorb less nitrogen, calcium, magnesium, iron, manganese, copper and zinc. When the pH is under 6, the absorption of most nutrients is reduced, while iron stays stable and copper, zinc and manganese are absorbed in excessive quantities. So, you risk giving your plants the “wrong diet”, which in botanical terms, causes nutrient deficiency of its opposite, nutrient toxicity.
  • How the medium you choose behaves with changes of temperature is also important; some expand, and this may cause problems, including crushing of the roots.
  • Finally, it should be easy to clean and wash. Of course, you don’t want pathogens to gather on (and in) your growing medium.

Choosing the best growing medium for your hydroponic garden is a bit like choosing the wood to make a violin; yes, the strings are all important and so is the shape, but unless you choose the right material, the sound will never have that perfect ring…

Is a growing medium strictly necessary?

Technically speaking, you can have a hydroponic garden without a growing medium; however, most gardeners will strongly advise that you use one. 

What is more, using one will make such a huge difference on the management of your garden and of your resources (water, nutrients etc.) that the small expense for a growing medium is easily justified, and will actually save you lots of money in the long run.

What are the advantages of using a growing medium?

If you are still not convinced that using a growing medium is a smart and wise choice, just look at the difference it can make to your hydroponic garden:

  • A growing medium will allow a slow and constant release of nutrients and water to the roots of your plants. By with holding the nutrient solution and then releasing it slowly, your plants will be able to access it long after you have irrigated them.
  • A growing medium will improve the aeration of the roots. Why? The pores of the medium will also keep pockets of air. This, especially with some systems, like the wick system, deep water system and similar, adds to the oxygen available to the roots of your plants. 
  • The growing medium will keep a stable level of humidity around the roots of your plants. Avoiding any sudden changes in temperature, humidity, aeration, nutrition etc. is extremely beneficial to plant growth and health.
  • Consequently, using a growing medium can also help stabilize the temperature around the roots. Air can change temperature very quickly, while solids and liquids tend to preserve it. So, if there is a sudden change in temperature, a growing medium will like a temperature regulator.
  • With some systems, like ebb and flow and drip hydroponics, where you provide your plants with the water solution through irrigation cycles, if you use a growing medium you can reduce the frequency of these cycles, thus saving on water and on electricity.
  • In case your system breaks (like if the water pump stops working), your plants will have longer autonomy. This can be a life saver if you have a crop depending on the nutrient solution and a pump to repair or change… Especially if it happens when stores are closed…

As you can see, if you use a growing medium, you can have much better control on the growth and health of your plants, on how you use nutrients and water, on the atmospheric conditions of the microclimate of your garden, and on the independence of your garden in case of faults and breakage.

And all this while actually reducing the amount of work and energy you put in. In 1979, The Clash had a single out called ‘Bank Robbers’ and the B side was ‘Rudie Can’t Fail’…

Well, with hydroponic growing mediums, all gardeners can be called “Rudie”.

Are there any drawbacks to using a growing medium?

“Nothing is perfect in God’s perfect plan,” Neil Young used to sing back in 2011… Still, when it comes to using a growing medium, the disadvantages are really small:

  • You will incur a small initial set up cost. However, growing mediums are very cheap, and some you can even get for free if you are in the right place (pine bark for example, or coconut coir).
  • The growing medium needs some “maintenance”. You will need to wash it before using it and even sterilizing it is not a bad idea. But this is only when you change crops, not something you need to do every day, or week…
  • You will need mesh pots or containers; you can do without them if you don’t use a growing medium, but not if you do. Still, even these are very cheap.
  • The main “problem” is choosing the best one for you; there are many growing mediums used by gardeners all over the world, each with different qualities and behaviors, but this is something we will see very soon.

So, if nothing is perfect in God’s plan, it is also true this may remind us of our role as gardeners, help along with the work of Nature, and, at least in this case, she is really asking very little from us…

Do all hydroponic systems use a growing medium?

Not all hydroponic systems need one, and not all methods can use one. Some, however, depend so much on it that doing without is almost unheard of, even nonsensical.

  • For instance, you cannot use a growing medium with aeroponics. In this case, the medium would literally be an obstacle to the nutrient solution you spray onto the roots. How can the droplets reach the root system of your plants if there is a solid mass around them?
  • With methods like the drip system, on the other hand, you cannot reasonably do without a growing medium. Again, this is for a mechanical reason. If you drop water from a hole (faucet, etc…) onto the roots of a plant, the chances are that it will almost always fall on the same place, the same root or part of the root system. The others would dry up and diet. So, we need a material that conveys the nutrient solution to all the roots.
  • With the wick method, you will need a growing medium; in fact, for it to work, you need capillary action, which is what happens in a sponge: you wet it on one side and it naturally speaks throughout the pores of the sponge. This effect cannot be achieved without a porous medium.
  • With other systems, like a deep water culture, the function of a growing medium is very much reduced to aeration. The nutrient solution is all around the roots anyway, but this system does have aeration issues, and little pockets in the medium do give some extra “breathing space” to the roots. With this system, however, use a medium with low water retention (clay pellets, pumice or lava rocks), as what you need is air rather than water in them.
  • Finally, with ebb and flow and nutrient film technique using a growing medium is recommended, but they can function without.

This should give you a broad perspective on using (or not) a growing medium according to the hydroponic method you choose.

This is a good start, but now, after this general “overture” , it is time to dive deep into the “underwater world” of growing mediums, a bit like Wagner does in Tristan and Isolde…

Ready for the some “drama” now? Not real drama, actually, just lots of facts, details and tips…

How Many Growing Mediums Are There?

Hydroponic gardeners have been experimenting with different growing mediums for decades, but it was only when rock and roll started from vinyl records that researchers understood importance of using the correct medium; in the 1950s, in fact, studies in hydroponics found out that using a poor, inadequate growing medium had a negative impact on the plants you grow.

Over the years, three main groups, or types, of growing mediums have come out as being the best for hydroponic gardens:

  • Pebbles and small stones.
  • Foam materials
  • Natural organic fibers

Not all materials that fall into these categories are suitable; however, these are three groups of materials that comprise all the growing mediums.

1: Pebbles and stones

Pebbles and stones

From the idiom “a rolling stone gathers no moss” comes the name of one of the most famous bands in history, but this old saying also tells us something about why pebbles like expanded clay, lava pebbles, vermiculite etc. are good growing mediums… Let me tell you why…

  • To start with, they are easy to clean and wash, which brings us back to our saying; you don’t want algae growth and especially rotting organic matter to accumulate on your growing medium, because this can be a breeding ground for bacteria and pathogens.
  • Next, they are suitable to any mesh pot shape; you don’t need to cut them to measure.
  • They are also very durable; stones will outlive you and very likely even your garden… You buy them once, and keep them forever.
  • You can play with the different sizes of the pebbles; this may look irrelevant but for expert organic gardeners it does make a difference; some plants and crops grow better with large pebbles (trees in the Dutch water system), others with smaller ones (small crops in general).
  • They are easy to combine; different materials have different properties, and you can get the best of both worlds using two together, or even more. Perlite and vermiculite, for example, is fairly common, and we will see why soon…
  • They can even have aesthetic value; if you have a decorative garden, even a small one at home, this can be a decisive factor in your choice.
  • They are organic on the whole. We will look at this in detail when we discuss each individual medium.

2: Foam materials

Foam materials

Growing mediums like rockwool, oasis cubes, floral foam and even polyurethane foam insulation can be used as growing mediums.

I will be straightforward with you: they are not my favorite choice and they do not the most popular among hydroponic gardeners. But first, let’s look at their advantages.

  • They are very light; this has some advantages especially in vertical gardens and hydroponic towers.
  • They are very cheap and widely available; the chances are, if you wish to set up a small garden, that you can find something in your attic that you can use as a growing medium in this category, even the old piece of insulation left over from that renovation job you had done to the roof…
  • There is a fairly wide range of materials, which also means different internal structures (bigger pores, capillary ones etc.)

However, there are some off-putting factors you will need to take into consideration:

  • They are not as easy to clean as pebbles; after a while, algae will grow and die inside the foam materials you use, and this may cause disease.
  • You can only recycle them downsizing… I’ll explain this; with pebbles you can move them from a smaller pot to a bigger one; this is harder with foam materials and even messier. You can either use a mesh pot of the same size when you change crops, or a smaller one, cutting the material into smaller chunks.
  • On the whole, they are not eco-friendly; floral foam and oasis cubes are made from phenolic foam, with polyurethane, well, the clue is in the name, and even rockwool is not fully organic in most cases.
  • Some are brittle, and, adding this to cleaning problems, we can say that they are not durable.

3: Natural organic fibers

Natural organic fibers

Hydroponics is a branch of organic gardening, thus, the enthusiasm for eco-friendly solutions should come as no surprise.

If you are coming to hydroponics with this perspective, then natural organic fibers may be a very appealing option for you.

Pine bark, pine shavings, coconut coir, coconut chips and even rice hulls have now become common so, you will be drawing on a well established tradition.

Still, they have many pros but also some cons.

  • The main appeal of these fibers is that they are, in fact, fully organic.
  • Some, like coconut chips and pine bark, do have an aesthetic value; if you want your garden to have that “mountain cottage look”, then, you know which medium to choose already…
  • They have very good internal porous structures; because they are natural, the air and water nutrient are absorbed in a wide range of pores sizes, this does mean a more uniform and prolonged release to the roots of your plants.
  • They are easy to recycle for different-size mesh pots, just like pebbles.
  • The choice of materials ranges in size from big chinks to very small husks; this means that you have a choice when it comes to the needs of different crops.
  • They retain moisture for very long times.
  • They are cheap and easily available.
  • They are fairly durable, depending on the medium you choose, but not as durable as pebbles.
  • Finally, you can combine them very easily.

However, they do have some small disadvantages as well:

  • They are not as easy to wash and clean as pebbles.
  • They are slightly messier to use than pebbles, especially if you use shavings and husks.

A final note, more on fading than a high C, to natural organic fibers is that not all of them are fully inert; some, like pine bark, need to be aged if you want them to be as inert as possible. Once they are dry, though, they will not release nutrients into your solution or absorb them from it.

11 Different Hydroponic Grow Mediums And Their Pros And Cons

You can even improvise your own make shift growing medium; this has been done by amateur (and not just) hydroponic gardeners with a “free jazz” inclination or inspiration.

Yet, while breaking conventional rules and tried and tested methods can be good for experimentation, if you want to be on the safe side, you’d better stick to a list of growing mediums that have proved to be reliable…

On top of this, the list of mediums is fairly long, including common building material, cheap mulch and even plain sand… Shall we now look at them in turn?

1: Expanded clay (a.k.a. grow rock or even hydrocorn)

Expanded clay (a.k.a. grow rock or even hydrocorn)

Expanded clay is the Pachelbel’s ‘Canon in D’ of all growing mediums; possibly the most common, most easily recognized and most eclectic of all the ones we use.

If you heat clay, which is a fully natural material, at 2,190oF (or 1,200oC) it expands, forming small air bubbles inside, in a honeycomb structure.

It is widely used building material, cheap, light and very durable. Hydroponic gardeners soon found out that this is a very good growing medium, because it can hold the nutrient solution in its porous structure and then release it slowly. But there is more…

  • They are not as easy to wash and clean as pebbles.
  • They are slightly messier to use than pebbles, especially if you use shavings and husks.It is totally inert, which allows you to have full control on the nutrients you give your plants.
  • It has a neutral pH and, as you know, the pH affects the nutrient intake, the electric conductivity of the solution etc.
  • It is super easy to wash and sterilize.
  • It is very stable in different weather conditions (it does not change volume).
  • It is widely available (you can find it in most garden centers, building material retailers even in DIY stores…)
  • It looks good, because the pebbles are of that warm brown color and it has that “lava like” look, it is suitable even for decorative gardens.
  • It is very durable, long lasting and recyclable. In fact, unless you smash the pebbles with a hammer, it will last forever.They are not as easy to wash and clean as pebbles.
  • They are slightly messier to use than pebbles, especially if you use shavings and husks.

Even if expanded clay pebbles are very common, they are not perfect:

  • They have an excellent pore structure, which makes them ideal for drainage and insulation, however, this also means that they tend to drain fairly fast. The pores are big and, as they fill quickly, they will also empty fairly fast.
  • In terms of its environmental impact, however, while the material is fully organic, to produce it, we need lots of heat, which means energy, which, in many cases, means burning fossil fuels.

Still, because they are very cheap and durable, they can be used in combination with other mediums with longer water retention, like pumice or vermiculite.

2: Pumice and lava rocks

Pumice and lava rocks

Still within the “pebble” category, another cheap and readily available option is pumice and other porous lava rocks.

Pumice is a volcanic rock formed when a volcano erupts lava with lots of water and gas in it. The water evaporates quickly and this forms lots of bubbles and pockets inside of it.

It does have some good advantages, and it is also used in soil gardening.

  • It has good nutrient and air retention; because the pores and pockets are of many different sizes, it releases the nutrient solution and oxygen at different rates.
  • It provides a stable bed for plants thanks to its coarse and “grippy” surface.
  • It is very light; this is handy in terms of transportation and for tall and multi-layered gardens.
  • It is readily available and cheap.
  • It is organic.
  • It comes in many colours, from white to black via blue, green, brown and cream; thus, it is ideal for decorative gardens.

Pumice is very common with tomatoes and herbs grown with the nutrient film technique.

It needs washing and sterilizing before you use it, as it breaks easily producing dust. The most common range of pebbles is between 1 and 7 millimeters in size.

While some gardeners hail it as the “perfect growing medium” for hydroponics, it is sometimes too light for some hydroponic systems; in fact, it floats on water, so, while it is excellent for drip systems, wick systems, nutrient film technique, it does pose some problems with ebb and flow and deep water culture systems.

Pumice (and similar lava rocks) too can be used in combination with other growing mediums, like coconut coir.

3: Vermiculite


This mineral with a beautiful name has the internal structure of an accordion; it has, in fact, many internal layers with thin plates which create pockets that fill with water and air.

This, however, only after you heat it at 1,652oF (or 900oC). In fact, this growing medium expands with heat, a behavior that sets it aside from other mediums.

This mineral has many pros as a growing medium:

  • It is very light.
  • It has a pH of 6.5 to 7.2, which makes it suitable for most plants.
  • It is naturally sterile.
  • It is permanent; being a mineral, it will never deteriorate.
  • It has very good moisture, water and nutrient solution retention.
  • It is cheap.
  • It is a natural mineral.
  • It has a beautiful range of colours; it can be white, bronze, brown, green or black.
  • In film nutrient technique, the roots hold the vermiculite pebbles in place.

However, vermiculite is not a perfect growing medium either. It does have some major drawbacks:

  • Though is not pricey, it is not easy to find.
  • It may even hold too much nutrient solution, and in some cases, it has been known to have suffocated the roots. In fact, it can hold as much as three times its weight in liquids.

This is why vermiculite is often used in combination with another medium, one that allows good aeration, very often coconut fibers or, even more frequently, perlite, which we will see next.

4: Perlite


Another material with a beautiful name, derived possibly from its white “complexion”. It is a glass found in volcanoes, which, when erupted holds on to water inside.

When it is heated at 1,600oF (which is 870oC), it “pops”, a bit like popcorn and it expands to up to thirteen times its original size, becoming light and filled with small pockets of air.

We could see perlite as the complementary growing medium of vermiculite; in fact, while it does not hold water for long, it is excellent for aeration.

This is why the two are often found together, in different rations, though, usually 50:50 is the most common.

Starting with the advantages…

  • Perlite is light.
  • Perlite is a natural material.
  • Perlite is fairly durable and it can be reused.
  • It is excellent at holding air; in fact, in soil farming, it is used to keep the soil dry, especially with succulents.
  • It has a beautiful white color.

Still, you will never find a professional hydroponic gardener using perlite on its own, and this is because of its many drawbacks:

  • It is not good for retaining water; it dries up very quickly in fact.
  • Its pH is a bit high for most plants, between 7.0 and 7.5.
  • It produces a white dust which can be irksome and you don’t want to inhale; toxicology studies class it as a “nuisance” dust, not a toxic one, but they also complain of lack of data on its effects.
  • Using too much perlite can result in small problems with the nutrients you feed your plants; this seems to be due to its high pH.

5: Rockwool


Yet another building material that has found its way into the list of hydroponic growing mediums, rockwool has that feeling of early synthesizers used in music alongside classical instruments in the sixties and seventies…

Not only does it look like something from a movie or even television series from that era, but it is also an early industrial product coming from the transformation of organic material.

In fact, it imitates the fibers of plants, while being produced industrially.

It is, in fact, an insulation material which hydroponic gardeners have adapted into a growing medium.

If you are prepared to put up with a growing medium that looks cheap and industrial, then rockwool may be a practicable choice for you. In fact, it does have some advantages:

  • It is very cheap.
  • It is extremely light.
  • It has excellent nutrient solution retention and release rates; in fact, it has a fibrous texture, which, unlike regular pores, withholds liquids and air for a long time.
  • It also retains air well.
  • It is reusable.
  • It comes in different forms and shapes. In fact you can buy cubes, slabs, sheets, and all sorts of shape. However, there are two main types of rockwool material: brittle (known as “bonded rockwool”) and soft (it looks a bit like a mat, mattress etc.)
  • It is easy to cut and non toxic.

However, it also does have some major disadvantages, and its fortune as a growing medium seems to be declining steadily:

  • It has a very high pH: 8.0. Before you use it, you need to soak it overnight in a water solution with pH of about 4.5, and aim to have your rockwool pH in the range of 5.5 to 7.0. This process may need repeating more than once.
  • You should never allow rockwool to soak completely. If it does, it will suffocate the roots of your plants, as it will squeeze out all the air and fill only with the nutrient solution. This can result in root rot and even stem rot.
  • While it is made from natural, even organic materials, mainly chalk and basalt rock, the production and process are industrial and polluting. Not only this, but “bonded rockwool” has a resin in it, and this is most often chemical.
  • It does not look good at all.

6: Polyurethane foam insulation

Little did Pink Floyd know that their experimentation with synthesizers would lead to full blown techno music, but it did…

Similarly, with the development of the oil industry, came fully synthetic insulating materials, like polyurethane, a synthetic foam with a spongy and semi-rigid texture.

It is not very common with hydroponic gardeners, but it may be used as a makeshift growing medium in case of necessity.In fact, it does have some of the key qualities of a growing medium:

  • It is inert; it does not react at all with the nutrient solution.
  • It is light.
  • It is easy to cut and shape.
  • Its texture is 85% air pockets and 15% solid, which means that it does hold good quantities of nutrient solution.
  • It is very cheap and easily available.


  • Not all polyurethane is non-toxic; there are different types of polyurethane and their toxicity can vary.
  • You cannot sterilize it easily; the air pockets inside are fairly large, and they will allow algae to grow in them; when they die, they will rot, which can cause pathogens and bacteria.
  • It is not suitable for decorative gardens, as it is quite an eye sore.
  • It is not sustainable and not organic; if the idea of hydroponics is to have an organic garden, having such a large part of it made of a byproduct of the oil industry, well…
  • You will not easily find it in hydroponic retailers; because of its major drawbacks, most retailers prefer not to sell it at all, which says a lot.

7: Floral foam

Floral foam

Image Source- https://www.youtube.com/watch?v=n1Mdikw3GNo

If polyurethane is “in your face” synthetic, floral foam is a bit like EDM music; it may “look” more natural, but it is still synthetic. You may picture it covered in cut flowers in a beautiful composition, because this is how florists have made it popular. But you can also use it as a growing medium.

  • In fact, it is light and cheap.
  • It has good nutrient solution retention.
  • It is inert and non toxic.
  • It is easy to cut into shape.
  • It can have a certain aesthetic appeal.

However, there are some main disadvantages:

  • It is made from phenolic foam, which, in turn it is derived from many synthetic substances. Thus it isn’t in the least environmentally friendly.
  • You must be careful; if it gets waterlogged, it can suffocate the roots.
  • It is brittle and it crumbles easily. This is not just a nuisance; it can even result in particles in the water and even clogged pumps and pipes.

On the whole, while some people use it, it is maybe better only with limited and small applications. For example, if you have some and you desperately need it for seeding, you may as well recycle it, but I would not recommend buying it on purpose nor using it extensively.

8: Sand

Different Types of Hydroponic Grow Mediums (Which Is The Best) 1

Image Source- https://www.maximumyield.com

Welcome back to the natural world… After a trip into artificial growing mediums, from now on, we will breathe only fresh air, a bit like moving from computer generated to instrumental music. Sand is a readily available growing medium; it is basically rock in very tiny pieces, so, it has some good qualities as growing medium.

  • It holds the nutrient solution well.
  • It is cheap and readily available.
  • It has a neutral pH, around 7.0.
  • It is fully inert.
  • It is durable and it fits into any shape.
  • It can be of beautiful colors.

Still, even sand is not perfect:

  • It is very heavy; this does not make it adaptable for gardens that need to change in size and shape. Basically, once you have put it in a place, it should be its (near) permanent one.
  • For the same reason, it is not suitable for vertical gardens, towers and tall gardens.
  • A mesh pot will not hold it; so, while sand is fine for the wick system and the Dutch bucket system, it is not suitable for and ebb and flow system where plants have individual pots for example.

Hydroponic gardeners who use sand also like to mix it with another growing medium, usually perlite and vermiculite or even coconut coir; this is to provide better aeration, with a ratio of 70:30 or 80:20 between sand and other medium.

Finally, if you wish to use sand, choose the one with the biggest possible grains; this way, the pockets between them will be larger.

9: Aged pine bark

Aged pine bark

Pines and conifers are fast growing trees, used to make furniture, whole homes and many musical instruments, like guitars and even violins.

But what makes them appealing to hydroponic gardeners is their bark; thick and with natural chunks that are easy to separate, they have been used for epiphytes like orchids as a growing medium as well as mulch for decades.

However, before you use pine bark as a growing medium, you need to render it inert; fresh pine bark will absorb nitrogen from your nutrient solution.

Professional gardeners can remedy this by adding nitrogen directly to the bark they use, but if you want an easy life, your best option is to get aged bark. In fact, it does have some great qualities:

  • It is fully organic.
  • It is fairly easy to clean.
  • It holds the nutrient solution and air for long; this is because it has a fibrous structure, with pockets of many sizes, from very small (even invisible) to large ones.
  • It is very light.
  • It is cheap and readily available; in fact, it is a very common type of mulch.
  • It is durable.
  • It has a beautiful appearance.

However, even pine bark does have some problems, as gardeners know quite well.

  • The pH of pine bark is acidic; it ranges between 4.0 and 6.5 even with aged pine bark. Still, limed pine bark has a pH of about or just above 6.0.
  • Pine bark floats; this, as you may expect, makes it good for a drip system or a wick system, it may pose problems with an ebb and flow system.

Pine bark is often also used in combination with other natural mediums, like perlite and vermiculite.

10: Rice hulls

Rice hulls

Rice hulls break down easily, but they also have a very strong texture; this means that while they will absorb your nutrient solution, they will also have a basic strong structure. If you are thinking about them, here are the advantages:

  • They are cheap and easily available.
  • They are fully natural and have very low environmental impact. In fact, they are a byproduct of rice production.
  • They are very light.
  • They fit into every size and shape.

On the other hand…

  • Their pH is a bit high, between 7.0 and 7.5. However, parboiled rice hulls have a perfect pH for most plants, between 5.7 and 6.5.
  • They are not easy to wash.
  • They are not easy to separate from the roots when you uproot your old crop.
  • If the pH drops under 5.0, rice hulls can release man games, leading to manganese toxicity.

Rice hulls are rarely used as the sole growing medium. Instead, they are often used especially with pine bark, usually 30:70 or 40:60 rice and pine bark.

11: Coconut coir and coconut chips

Coconut coir and coconut chips

The Stradivarius of growing mediums is coconut; you can use both the coir (the fibers outside the husk) or husk chips. Both are excellent in many ways:

  • They are fully natural and have a very low environmental impact.
  • Their pH is neutral.
  • They are very light.
  • They hold the nutrient solution very well, having a very porous and fibrous structure.
  • They are very cheap and easy to find.
  • They can be washed easily.
  • They fit into all shapes and sizes of pots; in fact, coconut coir can get caught by the roots themselves of the plants.
  • They look natural, so, if you want your garden to be organic also in appearance…

“But,” you may ask, “is there a difference between the two and are there any disadvantages?”

Apart from the aesthetic differences (chips look better than coir), coconut chips also form bigger pockets.

You can, of course use both together, maybe with the coir lower down and the chips on top.

Finally, a little detail that hydroponic gardeners know well… Removing coconut coir from the roots when you want to change crop can be a bit “fidgety”…

What Grow Medium Is Right For You?

The range of hydroponic growing mediums is like full orchestra; there are so many “instruments” that choosing the best one for your “piece”, garden or crop, can take some time… But in the end, you will need to choose which “voice” you wish your garden to have…

Most hydroponic gardeners prefer fully organic medium with low environmental impact, and here, coconut coir and fibers are by far your best choice.

Others may prefer natural pebbles, like expanded clay and vermiculite or even sand. Few will choose a synthetic material, not just because they are not organic, but they also have quite a few drawbacks…

Then again, you can mix growing mediums to get the best “harmonic composition” for the plants you want to grow.

Still, whichever you choose, my final tip is to invest in the long term; a pH neutral, durable and recyclable growing medium will spare you expenses in the future and a lot of work as well.

Look at it like choosing a violin; a low quality one may be good to learn the basics, but a good one will pass down from generation to generation and always regale us with its beautiful notes.

Adriano Bulla

Written By

Adriano Bulla

After many years as an academic in London, Adriano Bulla became a writer, publishing books like A History of Gardening, Organic Gardening and Elements of Garden Design; he then decided to become a gardener, following his childhood dream, and has been following his dream writing and gardening professionally in Southern Europe, where he has specialized in new and innovative organic gardening fields and techniques, like permaculture, regenerative agriculture, food forests and hydroponics.

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One Comment

  1. Avatar photo Sandi Woodruff says:

    Thank you for the insights and musical references. I have been growing tomatoes outdoors for years, even starting them in the basement. But here in the Pacific Northwest, we can only have outdoor garden tomatoes from August to October.

    This year, I’m taking the crop down into the basement using hydroponics. Your articles have been very helpful. You have given me a better feel for what I can expect from my move to soil free gardening.