Diatomaceous Earth

Diatomaceous earth; a very long word for a very tiny thing!

Electron microscope image of tiny fossilised diatoms

Tiny fossilised diatoms magnified 1000s of times

What is a diatom

Diatoms are microscopic single-celled algae, living mainly in the oceans, but also found in freshwater and other moist environments. Salt water diatoms are the ones we interested in here, and they secrete silica to form a hard cell wall. When magnified, this silica reveals extremely complex and beautiful shapes and patterns, as you can see above.

What is diatomaceous earth

A small pile of diatomaceous earth

Diatomaceous earth

Diatoms have lived on Earth for millions of years. Their prehistoric cousins, when they died, sunk to the ocean floor and were crushed to become part of the sea bed.

Today, some of those ancient sea beds are exposed, and the fossilised remains of trillions of tiny diatoms form a chalk-like sedimentary rock that’s easily crumbled into a fine abrasive powder; diatomaceous earth.

Diatomaceous earth has many uses. The porous, sponge-like structure of the fossilised diatoms makes an excellent filter material commonly used in swimming pools. Its gritty abrasive nature is a good ingredient for polish. And being totally natural and non-toxic, it finds many uses in products for human and animal consumption.

Diatomaceous earth and slugs

A barrier of diatomaceous earth is extremely unpleasant for a slug to cross. The microscopic razor-sharp particles of crushed fossils slice through the slug’s protective slime, lacerating its soft underside and causing it to dehydrate and die. It’s also a moisture absorbing desiccant, sucking the fluid from the slug.

In exactly the same way, diatomaceous earth is often used to control parasites on both humans and animals. It cuts and scrapes away at the protective outer layer of many small insects, then the desiccating powder draws out the fluid, leading to dehydration and death.

But for us gardeners this can be a double-edged sword. Many insects are our friends and we don’t want to harm them. So it’s best to use diatomaceous earth sparingly and selectively in the garden.

Wise precaution

Be sure to use a product designed for garden use. Some types, such as for swimming pool filtration, have been chemically treated and will kill plants.

Diatomaceous earth is easily dispersed by wind and rain so it needs reapplying in unfavourable conditions.

Wise precaution

The fine powder can be irritating if inhaled, so it’s best to use a mask. The moisture absorbing properties can dry the hands, so gloves are advised for prolonged handling. It will dry the eyes if used carelessly.

Other interesting uses

Diatomaceous earth has many other remarkable uses. These include:

  • Toothpaste – The fine abrasive powder is non-toxic, making it a useful ingredient in toothpaste.
  • Water Filtration – With so many places for contaminating particles to become lodged, diatomaceous earth makes excellent filter material for ponds and swimming pools.
  • Chemical Spills – The miniature fossilised ‘sponges’ soak up and trap the liquid, making it easier to remove and safely transport from the scene.
  • Cat Litter – The super absorbent properties are put to good use as component of cat litter.
  • Explosives – Alfred Nobel discovered that highly volatile nitro-glycerine could be made more stable by absorbing it into diatomaceous earth; hence was born dynamite.
  • Grain Storage – Food grade diatomaceous earth is non-toxic and can be used as an additive for both domestic and commercial storage of grain to repel and kill insects.
  • Medical Uses – Some people claim that diatomaceous earth has many health benefits. After all, a small quantity of silica is vital for a healthy body, and many essential minerals are lacking in a lot of today’s highly processed foods. But, although non-toxic, it’s always wise to seek the advice of your doctor before taking any supplements.

The Gardener’s Year

The Gardeners Year: book cover

The Gardener’s Year

Dad always said to me, “Gardening is tied to the seasons, and being a successful gardener is all about planning ahead.”

You need to know what you should be doing, when, and why, so what needs doing in August?

Read The Gardener’s Year by Alan Titchmarsh and get month by month advice that shows you how to keep your garden growing its best throughout the entire year.

The Gardener’s Year
Find out more

More gardening year books

What do you want to do now

The Gardener’s Year

by Alan Titchmarsh

The Gardeners Year: book cover

What to do in August?

Gardening is intimately linked to the seasons, and being a successful gardener is all about planning ahead.

Alan Titchmarsh gives you month by month advice and shows you what you should be doing, when, and why.

The Gardener’s Year
Find out more

Did you

A slug’s slime absorbs water, which is why it’s nearly impossible to wash it off your hands

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