Diatomaceous Earth
A fine powder made from fossilised diatom shells that damages the exoskeletons of crawling insects and causes them to dehydrate.
What it is
Diatomaceous earth (DE) is composed of the fossilised silica shells of microscopic aquatic organisms called diatoms. Food-grade DE is approved for organic gardening and has no chemical toxicity to mammals, birds, or earthworms. It acts purely through a physical, mechanical mode of action.
What it does
The microscopic sharp edges of diatom shells abrade the protective waxy layer of insect exoskeletons on contact. Once breached, insects lose moisture rapidly and die of dehydration. It is effective against any soft-bodied or thin-exoskeleton crawling pest that comes into contact with the powder.
When to use
Apply to dry soil surfaces, around the base of plants, or directly on plant foliage during dry weather. Most effective when the powder remains dry. Use when pest pressure is observed at soil level or as a barrier ring around vulnerable transplants. Reapply immediately after rain.
When not to use
DE loses all effectiveness when wet and should not be applied just before or after rain. Avoid dusting flowering plants heavily as it can harm bees that contact it. Do not inhale the powder during application as fine silica particles irritate the respiratory tract. Use food-grade DE only, never pool-grade.
How to apply
- 1
Wear a dust mask and eye protection before handling. Choose a calm, dry morning for application.
- 2
Apply a thin, visible layer of DE powder to dry soil around the base of plants using a duster or a clean, dry shaker.
- 3
For foliage pests, lightly dust the upper and lower surfaces of leaves, focusing on areas of pest activity.
- 4
For slug and snail barriers, create a continuous ring of DE powder around individual plants or entire bed perimeters.
- 5
Reapply after rain, heavy dew, or overhead irrigation, as moisture completely neutralises the mechanical action.
Garden, by Willowbottom recommends only organic, wildlife-friendly solutions. No synthetic pesticides, no harmful chemicals - ever.