Organic GrowingPest Control

How to Unleash the Power of Organic Pesticides

All gardeners and greenhouse growers eventually find themselves battling a pest insect or pathogenic fungus. Fewer things are as disheartening as watching your hard work (in the form of beautiful plants) being compromised by an unwanted pest or pathogen. Once the pest has been identified, the grower should waste no time implementing a treatment program. Beneficial insects are a great first line of defense but often a pesticide will be necessary. With a plethora of insecticides and fungicides on the market it can be overwhelming for the average greenhouse owner to decipher what pesticide should be used and how.

In addition to the multitude of choices growers face in their quest to eradicate a pest, they must also determine the safety of the product they intend to use. It is the gardener’s responsibility to find a product that is not only safe for the plants but for his or herself as well. After all, we are gardeners because we enjoy spending time in our greenhouses with our plants. If growers choose a treatment program that creates an unsafe environment, they cannot fully enjoy their hobby. At the same time, if the grower doesn’t quickly act to destroy the pest there may be very little left in the greenhouse to enjoy. This is how garden pests create a Catch 22 situation for the horticulturist. The pests must be destroyed but the health of the gardener and the plants must be sustained.

My solution to this double-edged sword is organic pesticides. Although organic pesticides should still be applied in accordance with the recommended safety guidelines, organic pesticides are much safer for horticulturists and their plants than their synthetic counterparts. There is less concern about adverse residual effects from organic pesticides which means growers can safely go back to enjoying their gardens quickly. Over the last several years there have been positive strides made in the organic pesticide industry. Organic pesticides that rival, and in some cases surpass, the effectiveness of chemical treatments are being introduced to the horticultural community at a fast rate. This is due to consumer demand and increasing technological advancements used to extract the concentrated active ingredients. This combination has increased the effectiveness of organic pesticides and even has larger scale, commercial growers leaning toward organic pest control.

Once a horticulturist decides to use an organic pesticide over a synthetic, their quest is far from over. Gardeners must choose from an overwhelming number of organic pesticides. A good starting point is to take a close look at a product’s label. This will reveal the active ingredients contained within, the concentration of each, and the manufacturer’s safety guidelines. Some products contain a single active ingredient while others combine multiple ingredients. The following is a list of common organic active ingredients contained within popular organic pesticides. Knowing a little bit about how each active ingredient works will help you find the proper solution to your problem.


Pyrethrins are a natural derivative from chrysanthemums. This organic compound has been used in horticulture for many years due to its low toxicity to humans and animals. Pyrethrins are extremely toxic to insects and can be used to eradicate a wide variety of pest insects. It is imperative to read and follow the manufacturer’s safety guidelines because the concentration of pyrethrins can vary greatly from product to product. This means that one pyrethrin product may only require rubber gloves during application while another pyrethrin product may require respiratory equipment or complete evacuation for an extended period. Pyrethrin-based insecticides, and all insecticides for that matter, should always be applied in accordance with the directions on the packaging.


Spinosad is an organic compound based on the bacterial species Saccharopolyspora spinosa. These specialized bacteria disrupt the nervous system of insects which makes this product effective on a wide variety of insect species. Spinosad is highly effective both as a contact killer and when ingested by the bugs. It has been shown that Spinosad is generally more effective at treating the larvae stage of many insect species than the adult stage.


Azadirachtin is the ingredient that makes neem oil an effective insecticide. This article explains how azadirachtin and neem are different. Once isolated, azadirachtin can be further concentrated to create a powerful organic insecticide. This insecticide works in a few different ways on pest insects. First, azadirachtin functions as a deterrent. Insects will sense azadirachtin on the leaf surface and quickly move on. Secondly, azadirachtin works as an insect growth regulator by compromising an insect’s ability to molt. When insects come in contact with or ingest azadirachtin, they are no longer able to molt or reproduce and the insect colony dies off. Last, but not least, azadirachtin works as an anti-ovipositor. This means the insects will not lay their eggs.

Neem Oil

As previously mentioned, neem oil contains the powerful compound azadirachtin which makes it an effective insecticide. Neem oil also has a natural anti-fungal property making it an effective organic fungicide. However, not all neem oil is created equally. The extraction method used has a great impact on the retained active compounds. Cold pressed neem oil contains the highest concentration of neem’s active pesticidal compounds.

Insecticidal Soaps

Pure castile soap or products sold as insecticidal soaps are a great organic treatment for soft-bodied insects, like aphids by suffocating them. Insecticidal soaps can also work as an emulsifier when mixed with other organic pesticides which helps keep the active ingredients on the leaf’s surface longer. This increases the effectiveness of the treatment program and helps growers get their money’s worth out of the pesticide.

Garlic Extracts

Garlic extracts are becoming more popular in organic horticulture. This powerful plant has a natural fungicidal property and the ability to destroy bugs on contact. As an insecticide, garlic extracts work most effectively as an insect deterrent. Because insects are adversely affected by garlic they will immediately pack up and find another place to live. Many pesticide companies are combining garlic extracts with other organic active ingredients to maximize effectiveness.

Clove Oil

As with garlic extracts, clove oil is becoming a popular additive to many organic pesticides. Products made with clove oil are excellent contact killers. There are products on the market that use dried cloves in their extraction process. These products are effective as a deterrent but generally not as effective as a contact killer. 

Rosemary Extracts

Special compounds found in rosemary extract block the octopamine receptors of many insect varieties. Insects sprayed with a rosemary extract solution will experience paralysis and eventually death. Because octopamine receptors are specific to insects, rosemary-based insecticides will cause no adverse effects for mammals or birds.

Cinnamon Oil

Cinnamon oil is becoming more popular as an additive in organic insecticides. This extract works by disrupting an insect’s neurotransmitter. Because these neurotransmitters are specific to insects it makes this type of insecticide extremely safe for people, pets, and other vertebrates.

Spearmint Extracts

Spearmint extracts have been shown to work as a deterrent to a variety of insects. Few plant species are sensitive to spearmint which makes spearmint-based insecticides great for small or sensitive plants. Spearmint extracts can be mixed into a solution and young plants, or seedlings can be submerged for complete coverage.

Thyme Oil

Thyme oil is another common additive to organic insecticides. Thyme oil has a deterrent property and has been shown to repel a wide variety of insect species.

Diatomaceous Earth

Diatomaceous earth is comprised of the fossilized remains of diatoms. This substance works as a contact killer. As the insect crawls by, tiny shards in diatomaceous earth cut the exoskeleton of the insect’s body causing it to lose moisture, dehydrate, and die. Diatomaceous earth is a great organic insecticide for slugs, fungus gnats, or any other insect that spends a portion of its life cycle crawling around the soil.

Frequency Infused Water

Of the more recent organic pesticides to hit the market, frequency infused water is one of the most interesting and exciting. These pesticides are based on the works of Royal Raymond Rife and utilize his theory that pathogens can be weakened or destroyed by energetically exciting destructive resonances in their constituent chemicals. In other words, everything has a particular frequency that, when matched or excited, can be used to destroy it. A good example of this phenomenon is a crystal glass broken by an opera singer. As soon as the destructive frequency of the glass is matched by the singer’s voice, the glass shatters. Along the same lines of thinking, if a pest’s destructive frequency is matched the pest can be destroyed. Since most of us don’t have an opera singer at our disposal, pesticide manufacturers had to find another way to deliver these frequencies. What they found is water has the unique ability to hold frequencies for a given amount of time. When water is infused with the proper frequencies specific to a given pathogen and that water is sprayed onto the pathogen, the pathogen will be destroyed. I know this all sounds too good to be true, but companies have proven this technology works. This exciting, new technology could be the future of organic pesticides.

There are a multitude of choices a gardener must sift through when their greenhouse is disturbed by an unwanted visitor. Restoring tranquility becomes an instant priority and at this point a gardener must research the best options. As we learn more about the potential dangers associated with chemical pesticide treatments it only makes sense to turn toward a safer alternative. The consumer demand is pushing scientists to uncover new organic compounds and new extraction methods that increase the effectiveness of organic pesticides even further. Our greenhouses and gardens are places of sanctuary and sometimes, to retain that sanctuary, it becomes necessary to rise up against unwanted pests. We do this in a healthier and safer manner when we unleash the power of organic pesticides.

Eric Hopper resides in Michigan’s beautiful Upper Peninsula where he enjoys gardening and pursuing sustainability.

Related Articles & Free Email Newsletter Sign Up

Common Sense Insect and Disease Control in a Natural Greenhouse

How to Understand Organic Growing Certification

Organic Pest Control for Greenhouse Gardening

Shop for High Quality CBD Products

Subscribe to our Free Email Newsletter

Comment here