When hydroponic gardeners think of growing media, crowd favourites like expanded clay and coconut coir usually come to mind. While these options are indeed hydroponic, they’re not the only options on the market. Often overlooked, pumice is a powerhouse alternative to these big names and in today’s newsletter, we will explain why.

Before we do, let’s back up a little bit and talk about exactly how the product is made: 

Pumice enters the world with a splash. 

As volcanoes explode, gas is released, which, in turn, makes lava foamy. When this foamy lava cools, it hardens, creating what we know today as pumice. 

Today, we’re talking about pumice and the various ways you can use it in your garden, but it’s worth mentioning that it also has a wide range of applications in other industries. For example, It’s popular in the beauty industry as a mild skin exfoliant and is used as an abrasive inside household cleaning supplies. 

In the garden, pumice’s lightweight and porous nature makes it ideal for top dressing, amending and can even be used as a hydroponic grow media. 

Here are just a few of the reasons we’re obsessed: 

First of all, it’s excellent at retaining nutrient. This is thanks to all those foamy bubbles we spoke about earlier. As the pumice cools, the bubbles pop, forming ‘pockets’ (the perfect natural nutrient storage spot). 

Second, pumice is a pro at improving the drainage within your existing grow medium, making it perfect for any plant that hates getting its feet wet.

We’ve noticed that growers will often make a direct comparison between pumice and perlite, and In fairness, these two hydroponic mediums have a lot in common. 

They’re both derived from volcanic glass and when it comes to gardening, they both serve similar purposes in terms of nutrient retention and soil aeration.

That’s where the similarities end, and where perlite falls short, pumice measures up. 

One benefit of perlite, for example, is its lightweight. 

Unfortunately, the difference in weight between perlite and the medium it’s mixed with means perlite will eventually float to the top of whatever grow container it’s in. At this point, the gardener will have to remix their medium, a job that risks transplant shock and opens your plants up to disease. 

Pumice, on the other hand, is light enough to make it easy to use while still being able to mix and stay mixed with your chosen growing medium. 

Pumice has some obvious advantages from a sustainability standpoint as well. Where perlite is mined, pumice is harvested from already erupted volcanoes, making it both renewable and sustainable. 

At this point, we hope we’ve won you over, and you’re thinking about how you might incorporate Pumice into your gardening routine. There are several ways you can go about this. 

If you’d like to add pumice to your grow medium, we’d recommend doing so in a ratio of two parts coco coir to one part pumice for most plants. If your plant is especially hardy, increase the ratio of pumice (1:1). If your plant is especially delicate, increase the percentage of coco coir (3:1). 

We also recommend pumice as a top dressing – in fact, this is our preferred way to use it! 

Pumice as a top dressing is an excellent choice for three reasons. 

Firstly, it’s a powerhouse for controlling fungus gnats by naturally creating an inhospitable environment for breeding. 

Secondly, it looks very attractive.

Third, if you are a diehard perlite user, you can add pumice as a top dressing to prevent your perlite from blowing away in the wind. 

At Aquaponics WA, we stock pumice in 4 size grades to suit different plants and applications. At only $49.90 for a 25L bag, amending your garden with this powerhouse media is a no-brainer and will pay long-term dividends. 

As always, thank you for tuning in to another edition of the Aquaponics WA and Hydroponic Xpress newsletter. If you have any questions about adding pumice to your garden, please call us at 1800 222 640 or come in-store and ask our friendly team.