Choice Overload: Navigating the Confusing World of Grow Media

In 1986, Hydroponic Xpress was born; to be frank, the soil quality in WA wasn’t cutting it. Back then, our choices when it came to grow media were far and few between and the options that were available were hard to come by. A lot has changed since then. Now, growers are faced with too many choices rather than not enough (we know, a great problem to have). Today we’re going to talk about the pros and cons of the options on the market, and which one/s are right for you.

Here’s the thing. Not all grow media is created equal.

Sure, all grow media is designed to support healthy, happy plant growth but how this is achieved and what your grow media is made of play a huge role in the success of your hydroponic garden.

No matter your choice, grow media should provide a number of benefits to support your plant.

Firstly, your medium is the only thing keeping your plant vertical, so it goes without saying that you need to pick something that has the ability to hold your plant upright.

Next, and we’ve been through this one before… Your. plants. need. oxygen.

If your media is too dense, your plants won’t be able to breathe and water won’t drain freely. This adds up to drowning AND suffocation – if that isn’t a combo for the worst way to go, we don’t know what is.

Finally, you want to pick a growing media that is going to hold water AND nutrient, allowing your plants to uptake all that good stuff on their own schedule.

Ultimately, the type of media that will suit you will depend on multiple factors. For example, the needs of your plants ( pH levels, sunlight/drought tolerance), the type of system your plants are in and budget.

With all of the above in mind, let’s talk about the ins and outs of some common media varieties. First up, peat moss.

Peat moss is a moderately priced hydroponic grow medium with an acidic pH and a short lifespan compared to other alternatives. There are many types of peat moss on the market, but sphagnum moss is by far the most common.

Peat moss is a double threat because it’s great at holding water (peat moss can hold up to 10x its own weight in liquid), and it’s great at releasing excess water.

Peat moss is ideal for acid-loving plants like blueberries, but for plants that like a more basic pH, peat moss might not be the right choice.

It’s also worth mentioning that from a sustainability perspective, peat moss can take centuries to form. It’s in finite supply and, therefore, not sustainable in the long term.

Next, let’s talk coco.

Coco peat or coconut coir is made from (you guessed it), shredded coconut husks. Coco peat is a great, budget-friendly grow medium with a neutral pH, but, like peat moss, its useful lifespan is relatively short.

Coco peat is sold loose, in blocks or in sheets which all triple in volume when saturated. Coco coir holds moisture well and is fully renewable and biodegradable as well.

Unfortunately, coco peat can be high in salt and chlorine, so make sure you check packaging for buffering instructions prior to use.

Next up to the firing line is vermiculite; a medium created by heating mica (a mineral) to over 1000 degrees. Vermiculite boasts reusability and is extremely lightweight, but does come with a high price tag.

While vermiculite is awesome at retaining nutrient, it doesn’t drain well which often leads to problems with root rot. While most other medium types can be heat steralised, vermiculite cannot be which does make it harder to reuse.

It’s also worth noting that by nature, vermiculite holds a very small amount of asbestos, so take care when handling. We tend to use vermiculite as an amendment, rather than a medium on it’s own, in a ratio of one part vermiculite to two parts perlite.

Now, because we can’t believe we haven’t already, let’s talk about expanded clay.

And honestly, we don’t have much to say that couldn’t be used as a glowing review.

Expanded clay is affordably priced and readily available – especially when you consider it can be washed and reused almost forever (the leca we use on premises is the same stuff we were using 30+ years ago).

Clay balls come with other advantages as well. For example, they make harvesting a breeze (no more detangling and separating roots from soil) and their porous surface provides effective drainage and aeration.

When it comes to water retention, expanded clay falls short compared to other medium choices – although we often use expanded clay on it’s own with spectacular results.

To ensure your plants have a steady supply of water and nutrient when using leca, simply place a saucer of water underneath your pot, or, use a pot with a built in reservoir like our bato buckets. We’ll link these for you below!

Okay, so this has been quite the newsletter and while there are many more grow media options out there, the last one we’re going to talk about is perlite.

Perlite is an affordable and extremely lightweight volcanic stone that is produced in ‘grades’ ranging from 0.1mm all the way to more than 3mm. Perlite is pH neutral and technically reusable since it does not biodegrade. Being a host for algae, we generally only reuse our perlite 3-4 times.

Perlite offers great water retention and is very porous, meaning it provides plenty of aeration and oxygen-holding capacity.

On the downside, perlite is a skin and eye irritant, so it’s important to wear the appropriate PPE gear when handling. Secondly, because perlite is SO lightweight, it has the propensity to blow away in the wind (or if you’re using fans). We fix this problem by applying a layer of expanded clay on top of our perlite medium, which effectively weights it down.

And there you have it, the rundown on five of our favourite media types. There are quite a few we had to skip today (we’re looking at you, potting mix), so maybe that calls for a part two…

In any case,  thanks so much for reading through this month’s newsletter and from the whole team at Aquaponics WA and Hydroponic Xpress, happy growing.