For as long as vermiculite has been in New Zealand, there has been a bit of confusion in the gardening population over whether it’s safe to use in your gardens. Does it present a health hazard? Does it contain asbestos? Below, we provide the low down on this valuable and versatile naturally-mined product.

What is vermiculite?

Vermiculite is a naturally-occurring mineral that expands when exposed to intense heat. It’s shimmery and gold, it looks like it consists of several layers, and is incredibly lightweight. Its composition makes it ideal for use in horticultural settings as well as for fireproofing and even insulation.  

Avid gardeners also love vermiculite for seed cover. It has excellent water retention properties, releases nutrients into your plants, and works beautifully with potting mix and other media. What’s more, those who use vermiculite are delighted with how it promotes root growth and aeration – all while being pH neutral to prevent it from rotting.

Clearly, vermiculite is a go-to material in a gardener’s arsenal, so why the hesitation for its use? We’ll go into that…

Vermiculite mine in Libby, Montana

From 1920 until around 1990, the vermiculite mine in Libby, Montana, was responsible for the majority of the world’s supply of vermiculite. It featured prominently in potting soil, fertiliser, and even building insulation. At the time, there was no reason to think that any hidden nasties were lurking within those vermiculite granules.

However, after around six decades of vermiculite mining under the trading name of Zonolite, it was discovered that the vermiculite was contaminated with naturally occurring Tremolite-Actinolite asbestos fibres. They were present in the same area during mining and posed a health risk when breathed in. As a result, any home that featured Zonolite products in North America could put its occupants at risk if they were to expose those materials.

Once the asbestos was discovered, the mine closed in 1990. Periodic tests have been carried out on other vermiculite mines since, with no signs of asbestos.

People who used vermiculite products, such as for attic insulation and landscaping supplies from Zonolite in North America were advised of their options at the time. The recommendation for insulation, in particular, is not to touch it. As long as it remains undisturbed, it’s unlikely to pose a safety risk. 

The same rule applies to asbestos products in New Zealand. Unless the asbestos is exposed or damaged, it may not pose a risk to human health. 

Why is asbestos harmful?

It’s hard to believe that a natural mineral could pose a health risk, but that’s the reality with asbestos. When you breathe in the fibres, they become trapped in your nose and throat mucous membranes and some travel through to your lungs and digestive tract. As your body can’t break these fibres down, they can cause diseases such as asbestosis, lung cancer, and mesothelioma.

Should I be worried?

If you’re a gardener who loves the value for money and versatility that vermiculite provides, then no, you shouldn’t be worried. Not only was Zonolite branded vermiculite not sold in New Zealand, but no other mines were shown to have asbestos in them either. This product is asbestos-free and always has been in New Zealand.

What’s more, vermiculite is non-toxic, pH neutral, rot-free, and sterile. It acts as an excellent seed covering and offers unbeatable value with a stunning natural gold colour at the same time.

Gardening material dust

Knowing that vermiculite does not contain asbestos can be a weight off of many people’s minds, but that doesn’t mean you shouldn’t still put health and safety first around any dust or dirt you will be using in your garden.

When you are working with any gardening product that lets off any kind of dust, it’s paramount to protect your lungs. Wear a face mask while handling materials, and even consider eye protection as well.

Make sure you follow all instructions and warning labels on packaging, carry out gardening without distractions, and ensure you use chemicals as directed and with protective clothing, gloves, and equipment. If you’re not confident handling potting soil and other similar materials, there is bound to be a gardening expert near you who can offer assistance.

So, can I use vermiculite?

In short, yes. As long as you protect yourself against any dust from any potting media, you can enjoy a safe gardening experience. Vermiculate is asbestos-free and ready to take your seed growing to the next level!