How To Use Diatomaceous Earth For Indoor Gardens A Guide!

Diatomaceous Earth is a chalk-like powder product that works as a pesticide for indoor gardens.

It is originally from natural sedimentary rock, rich in silica, which is minded and then ground into a chalk-like powder product. Simply known as DE (also known as Amorphous Silica or Diatomite), it is rich in silica from the shells of ancient, fossilized plankton algae.

As a general rule, apply diatomaceous earth to your indoor plants once a week to get rid of any pests. It can be applied by either sprinkling it on the leaves and stem of the infected plant or by spraying the plant with a solution of water and diatomaceous earth on the plant (1 tbsp. per gallon of water)

It works by dehydrating any pests which directly crawl onto it so it will be really useful to deter slugs and snails that like to leave a slimy trail, ants, aphids, flies, or even rodents – see how below.

It also has properties that deodorize smells so some gardeners use it in an area where bad smells occur from pet waste or a compost bin whose contents have become too wet.

How to use Diatomaceous earth for Indoor Plants?

You can use DE in two ways:

1. In powder form. Put the powder into a container with small holes. Sprinkle the white powder directly onto the leaves and the base of the stem. Any insects on the leaves will find that the silica dehydrates their entire system very quickly.

Take good care not to inhale the powder and also to wear gloves to protect your hands.

I would advise a mask and eye protection to protect both eyes and face because there is some concern about this powder settling in the lungs of humans. If you are asthmatic or have any lung problems, it might be better to avoid this powder or to ask somebody else to help.

2. As a spray. To mix DE with water, use 1 tablespoon of powder to a gallon of water in a spray container, then spray under leaves as required.

The powder is only effective when it is dry, not wet. It needs to dry out after rain before it becomes effective. So when you apply it, make sure your plant has already been watered beforehand and the leaves have dried out slightly. Then apply the DE powder or spray to the surface of the leaves and stem of your plant.  

Any aphids, gnats, or flies that land on it after DE application will become dehydrated quickly and it is particularly effective for pests like slugs and snails that require moisture to move. Any insects that come into contact with DE will also dehydrate rapidly.

To deter rats: Rodents do not like citrus and this is useful if you mix the citrus (or peppermint) in oil form directly onto the DE powder. You will need to place your DE powder in a small container and then you can add a few drops of the oil.

Diatomaceous earth is porous and gets absorbed very quickly. An added bonus is that DE retains the smell of the oil for longer than it does on a cotton bud or a tissue, so this protection lasts for longer.  You can top up the oil if needed when you can no longer smell it.

To deter ticks: If you live close to farmland or woods, there may be animals like deer which carry ticks and these can be a real problem in your garden.

Ticks can spread Lyme disease and Colorado tick fever to humans and to deter them, you can use DE once a month. Simply use an applicator and dust or spray a layer of DE on the whole lawn area. However, it is advisable to keep children and pets out of the garden while you are spraying the area.

When to Use Diatomaceous earth on Indoor Plants

Use the DE once a week directly on the leaves or stem of plants before the flowers appear on your plants. If it rains heavily you can give a second spray but DE tends to function well again as soon as it dries out so this is probably unnecessary.

The reasons why DE is not used on flowers are:

1. A zucchini flower becomes a zucchini which will be eaten by you. You do not want to eat this powder neat! However, some people swear by its oral consumption – see more below to help you make up your mind.
2. Pollinators like bees and hoverflies will come into direct contact with the DE and this will cause death. Bees are already in trouble with all the pesticides in their natural environment so please don’t use DE when bees are visiting your flowers.

If you have an anthill: Then apply the powder liberally to the top and the space should be cleared in about 24 hours.

For slugs and snails: Apply the powder or spray directly to the leaves. Any visiting slug or snail will not enjoy the dehydration.

For aphids, red spider mites, and other pests: Apply the spray on leaves weekly to keep them in check. It may take several applications if there is a heavy infestation.

If there is a smelly patch in your garden where the dog or cat tends to leave their waste, and it smells, then this is recommended by the manufacturer as a deodorizer.

The only problem is if there are flowering plants close by, particularly flowers that bees are likely to feed on. DE causes dehydration in all living things so it is important to use it in the recommended way to clean the area but not to poison everything that comes in its path.

How much diatomaceous earth Should you use

When applying the DE on top of the plant and the stem, put enough powder on it to see a visible thin, white coating on the leaves.

If you are using a spray, add one tablespoon of DE powder per gallon of water and shake the mixture well. Then spray the whole plant with the solution.

How often should you use diatomaceous earth

Once a week is sufficient for most plants. If you have a heavy ant or aphid infestation, you can apply a second coat after 4-5 days. Check the leaves using gloves and if there is still a lot of movement, then re-spray or use another layer of powder.

For treatment of ticks, once a month is suggested.

Is diatomaceous earth safe for pets?

DE is said to be non-toxic if used as directed. However, if this is a substance that dehydrates and kills pests, I would not say it is safe for pets to eat so make sure all containers containing it and plant leaves treated are out of their reach.

It is very important to wear some protection yourself while treating your plants. Although manufacturers say this is 100% natural, it does dehydrate all insect life it comes into contact with so better safe than sorry!

Wear gloves and a protective mask for your face to avoid inhaling the powder or spray. If it gets into your eyes or is swallowed, make sure you get medical assistance immediately.

Frequently asked questions:

Can diatomaceous earth be used outside or is it for indoor use only?

White DE is free from any processing, so it is reasonably safe for use in pots indoors and outside for specific purposes. See how to deter pests above. However, there is a pink form of DE that is chemically treated and this is poisonous for livestock and pets. So check the color, make sure it is white, and then use it as directed on the packet.

Is diatomaceous earth safe for human consumption too?

There is some discussion about the high numbers of lung problems for people employed in removing and packing diatomaceous earth.

DE is often reported to be useful in treating high cholesterol levels and some manufacturers claim oral consumption can also improve teeth, skin, nails, and hair. However, it is wise to speak to your doctor before taking any medication and this column does not recommend it.

How much diatomaceous earth do I mix with water?

As a general rule, mix one tablespoon of diatomaceous earth per gallon of water and use this weekly on plants that are not flowering or are infested with pests.