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Quassia: a Godsend for Gardeners

Kim has been gardening and growing her own food for over 27 years. She is a Master Gardener and loves to explore agricultural challenges.

Quassia Bark

Quassia Bark

Introduction to Quassia

Quassia amara is a small tree that grows in the Amazon. This tree is native to Brazil, Peru, Venezuala, Columbia, Argentina, Guyana, and Suriname (I have never even heard of this country). I don't remember how Quassia ended up in my 500 World Flora Quest, but there she is. There is very little information about this tree, it should be explored further.

I had stumbled upon a tropical plant database and a fantastic write up about this amazing tree. The author was a Leslie Taylor. I linked the full write up below. I had been looking for traditional uses of various plants and I had found in this write up, just that.

The indigenous people's of the area use the leaves and wood of this tree to treat a variety of ailments, from malaria, measles, indigestion, parasites, and the list goes on. A cold maceration is prepared that kills both lice and nits. This trees wood also kills mosquitoes and their larvae and is used to combat malaria, a mosquito born illness.

Standing water attracts mosquitos........which means buckets of water for dogs, swimming pools, drip pans, and toad pools are all subject to mosquito infestation.....

I had to acquire this.......yesterday.......

Quassia Maceration in Spray Bottle

Quassia Maceration in Spray Bottle

What this means for the gardener.....

First of all.......Only 1% of bugs are a problem in the garden. The rest of them.....we want to keep. They are beneficial insects. Whatever you spray on your plants will affect the good bugs as well as the bad ones. Before spraying anything on any of your plants, remember that. Bees, lady bugs, praying mantis, spiders, roly poly's are all beneficial insects. What you spray affects them alongside the bad.

When you garden find that 1%........aphids, spider mites, scales, creepy flies............. eck!. Not only are they annoying, they damage or even kill your plants!.

So what's up with all the pesticides? A pesticide, is any substance intended for preventing, destroying, repelling, mitigating any pest. Various pests. Not just insects. But harmful organisms, including herbs, and fungus.

Pesticide: kills multiple insects and pests. Nature offers many plants to deter and kill, pests.

Insecticide: An insecticide is a pesticide that kills adult insects and their larvae. There are many natural insectides growing in nature. Anise, Cedar, Cinnamon, Tea Tree, Neem, Eucalyptus, Garlic, Onion, Tobacco, and Quassia are only a smidgen of insecticidal plants.

Pediculicide: Kills Lice! Nature also provides us with plants that do this. Anise, Coconut, Neem, Tea Tree and Quassia have been used historically to kill lice.

Larvicide: Kills an insects Larvae. Primarily, Mosquitoes. Nature offers us this as well. Allspice, Dill, and Quassia are the only ones I have found.

Quassia does all of the itself.......

The importance of Quassia's abilities to kill all things that infect house plants is astronomical! This is a dream come true. If this works.......

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Insecticidal OIls

Various Insecticidal Oils

Various Insecticidal Oils

Natures Other Insecticides

Nature offers us many options for natural insecticides and pest deterrents. Some are used as companion plants to keep select insects (or pests) from attacking crops, others are made into sprays to kill or thwart off offending insects. Some are relatively safe, others can be poisonous if ingested.

The best way to control insects is to not have insects to control. But that is not always the case. Sometimes it happens. In that case, it is best to choose the least toxic yet effective remedy possible.

Here is an overview of some of natures natural organic pesticides.....

Insecticide (pesticide):

Anise: for Lice

Cedar: fleas and flies, Cedar wood is used both in the garden and in high end construction for its ability to repel insects.

Cinnamon: cats and deer despise cinnamon and additionally is used as a natural fungicide.

Tea Tree: ticks, bed bugs, and Lice

Eucalyptus: repels flies. Is planted to dry up mosquito breeding grounds.

Garlic: an effective companion plant for roses to deter aphids but also employed in a spray

Onion: also an effective companion plant to deter aphids, borers, and rabbits.

Tobacco: leaves are steeped in water for an effective insect deterrent. Not recomended for plants intended for consumption.

Quassia: has been proven effective at killing all stages of insect development

Neem: effective against white flies, aphids, caterpillars, thrips, leaf miners, mealybugs, scale crawlers, and beatles


Anise: has been used to kill lice, Anise Oil is added to a fat or oil and applied to hair.

Coconut: oil is used to smother the lice, killing by suffocation.

Neem: is used similar to coconut oil and kills Lice

Tea Tree: added to shampoos to kill Lice

Quassia: a cold maceration is used to kill Lice and Nits


Allspice: contains larvicidal properties

Dill: dill has been used as a companion plant to deter carrot white fly. It's oil added to insecticides to kill larvae.

Quassia: has been shown to be effective against Larvae, primarily mosquito's

Over the last 27 years or so I have fought the battle of bugs from inside to outside. I have planted groundcovers to deter ants, used oils in corners to deter spiders, created organic sprays from garlic, onions, and cayenne, added oils, and made homemade soaps. If it's not one pest, it's another one. Until now, there has not been one product to do it all, safely.

Using Quassia

And the testing began........

I dont like using chemicals. I swear I've tried every organic tip and trick known to man to avoid bugs in the first place.....however....

Spider mites are the biggest indoor problem. They kill your plant slowly by feeding on it from the undersides of leaves. They spin these nasty little webs which are easy to see. watch as your plant slowly dries up and just dies, sometimes practically overnight! Spider Mites are EVIL!

Black Gnats are stupid little flies that live in the soil. They are more annoying than anything else, but a houseplant problem nonetheless. They are relatively easily controlled with a larvaecide........

Aphids have been complained about, although I have never personally experienced them indoors. Outside, however, they have attacked my beloved roses and I have seen them on my clients lupines.

There are other indoor pests on the list, mealy bugs, scale, root aphids, rust mites, and a few more. Quassia should stop them all.

Using Quassia is easy. Place two Tablespoons of wood chips in a mason jar, cover with cold water, and allow to stand 24 (minimum) hours. Strain off the water to a squirt bottle. Spray infected plants liberally. You can literally watch spider mites scurry and die......

Spray the plants soil well and those nasty soil creeps are stopped dead in their tracks. For an even more effective soil cleanse, water the infected plant with a Quassia maceration.

Don't throw those chips out....they can be used a few times. And when you think you've sapped them dry? Recycle them to your potting mixture.

Additional and Useful Information on Quassia

I hope you found this information as useful as I did. I can't say enough positive things about it. Quassia is my #1 go to for pest plant care.

Please feel free to leave comments below. Share your Quassia experience, thoughts, and insights.

As always, Happy Gardening!

© 2017 Kim French


Judith Loring on November 29, 2017:

Good article. Quassia amara is also known as amargo, bitter-ash, bitter-wood, or hombre grande (spanish for big man). I originally used Quassia on your advice and I'll never use another pesticide! However instead of pouring the water off the bark and using that water in a spray bottle, I simply left the bark in the spray bottle. Just gets stronger and stronger and the bark pieces do not plug up anything.

Wikipedia ( says the name comes from Kwasimukamba or Graman Quassi (also spelled Quacy, Kwasi and Quasi) who was was a Surinamese healer, botanist, slave and later freedman of the 18th century, who is today best known for having given his name to the plant species quassia. Surinam is a sovereign state on the northeastern Atlantic coast of South America. It is bordered by French Guiana to the east, Guyana to the west and Brazil to the south. One of his remedies was a bitter tea that he used to treat infections by intestinal parasites, this concoction was based on the plant Quassia amara which Carolus Linnaeus named after him, as the discoverer of its medicinal properties. Quassia continues to be used in industrially produced medicines against intestinal parasites today. In contemporary accounts he was described as "one of the most extraordinary black men in Suriname, and perhaps the world."

Interesting that you call it a tree altho you are perhaps correct. One site calls it a shrub or rarely a small tree, growing to 3 m tall. ( Chemically, there is in the wood a share of 0.09 to 0.17% of quassin and 0.05 to 0.11% of neoquassin detected in Costa Rician plants. Quassin is one of the most bitter substances found in nature. Adverse effects on beneficial organisms is not found. In Switzerland, you can buy a licensed formula for organic farming.

Like any poorly studied alternative chemical applied to food crops, Quassia extract may have unknown health consequences. A study on rats in 1997 found that Quassia extract significantly reduced their fertility, reducing testes size, sperm quality and serum testosterone. See the site quoted above. That same site says that after soaking for 24 hours, it is cooked for 30 min. and then diluted with 2.6 to 5.3 US gal of water and used as a spray altho that recipe is more for spaying of hectares rather than on house plants or garden vegies.

Also used as a digestive, to treat fever, but with malaria, I'm not sure if it's used to treat effects of having malaria or as a tea to be drunk to not get malaria in the first place.

Thanks for writing this article. I hope it helps grow knowledge of this fantastic natural organic wonder!

Kim French (author) from Stevensville, Montana on November 25, 2017:

Thank you.

Alexa Rain from egypt on November 25, 2017:

Always you have special plants with wonderful benefits. Great Hub.

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