Description
Essential Oils for the Home & Garden
If you are trying to limit your exposure to toxic and synthetic chemicals in your garden and home essential oils can be valuable tools. They are well-known for their wellness virtues for humans, and can also be precious allies to protect your plants naturally and ecologically.
These oils have been used for thousands of years for their medicinal and cosmetic benefits, and their power lies in the hundreds of chemical constituents they contain. Whether you are trying to chase away garden pests from your vegetable or flower garden, protect your plants against diseases, or simply to improve their overall health, we can use these natural defences to our advantage in both our home and garden, using products you can store in your medicine chest. How cool is that!
Oregano Essential Oil
Highly valued in traditional wellness practices, Oregano Essential Oil (Origanum vulgare), native to Mediterranean regions, is steam distilled from the leaves and flowering tops of the herb. It has a strong, spicy, and herbaceous scent with warm undertones.
In the Garden
Origanum vulgare essential oil is used as a natural biopesticide due to its active compounds, primarily carvacrol and thymol. The essential oil is primarily targeted against stored-product pests, biting insects, and soft-bodied agricultural pests. Because it is botanical and biodegradable, compared to synthetic chemicals it is much safer for humans, beneficial insects, and the environment.
Origanum essential oil is highly volatile and evaporates quickly, which limits its residual effectiveness outdoors. Researchers are currently exploring methods like microencapsulation to prolong its agricultural shelf life and efficacy.
Origanum essential oil acts as a Larvicide and Contact Insecticide, a Repellent, and a Fungicide.
It acts as a deterrent and contact spray to protect vulnerable crops against Aphids and Whiteflies
Stored Grain & Pantry Pests
The oil functions as a highly effective fumigant and contact killer in enclosed grain silos against several pests.
Granary & Maize Weevils
The Maize Weevil (Sitophilus zeamais) is prevalent and destructive in South Africa. It is one of the most significant post-harvest pests affecting stored maize and cereals, thriving in our warm and humid regions.
Granary Weevil (Sitophilus granarius) is not that common in the tropics, and is usually restricted to cooler temperate zones or controlled indoor storage. It is officially recorded in South Africa as a pest of wheat, barley, and other grains.
Red and Confused Flour Beetles
These are two distinct but nearly identical species of insect that are common pests of stored dry food products like flour, cereals, and cornmeal, contaminating the food. These beetles are secondary pests, meaning they typically feed on broken or damaged grains rather than whole kernels. They are found worldwide in pantries, warehouses, and food processing facilities.
Yellow Mealworms/Beetles
Yellow Mealworms are the larval stage of the yellow mealworm beetle (Tenebrio molitor), a type of darkling beetle known for their role as a pest in stored grains.
The larvae are also a valuable, protein-rich food source for pets, livestock, and even humans. They undergo a complete life cycle from egg to larva, pupa, and adult.
Mediterranean Flour Moths (Ephestia kuehniella)
The Mediterranean flour moth or mill moth (Ephestia kuehniella) is a common pest of cereal grains, especially flour. This moth is found throughout the world, especially in countries with temperate climates.
Mosquitoes & Cockroaches
Oregano essential oil disrupts the nervous system of insects and can inhibit the growth of certain Mosquito Larvae. The strong aroma makes it highly effective at repelling mosquitoes and cockroaches.
Fire Ants
Fire ants (Solenopsis species) do occur in South Africa, but they differ significantly from the infamous invasive Red Imported Fire Ant (Solenopsis invicta) found in the United States and Australia.
South Africa is home to native Solenopsis species, most notably the Cape Fire Ant (Solenopsis punctaticeps). First recorded in 1865 in the Cape, they are widespread across sub-Saharan Africa. While they are perfectly capable of penetrating human skin with their stings, they generally live in balance with the local ecosystem.
The Tropical Fire Ant (Solenopsis geminata) is an introduced species that occurs in certain parts of South Africa, such as KwaZulu-Natal.
Bed Bugs
Two primary species of bed bugs feed on humans in South Africa, the Common Bed Bug (Cimex lectularius) and the Tropical Bed Bug (Cimex hemipterus).
Both species are flat, reddish-brown, and approximately the size of an apple seed, but they thrive in different regional climates. The Common Bed Bug is found nationwide, but thrives in moderate, cooler climates like Gauteng. The Tropical Bed Bug prefers warmer, tropical and subtropical areas, and is highly prevalent in provinces like KwaZulu-Natal and Limpopo.
As a Fungicide
Oregano essential oil exhibits broad-spectrum activity against agricultural and plant fungi, including Powdery Mildew, Blight, and various Mould spores.
Garden Spray
Mix 10-20 drops of the essential oil in 1 Litre of water with an emulsifier. Shake well, and regularly while spraying down the foliage of plants.
The Cotton Wool Method listed below is also effective.
In the Home
Highly valued in traditional wellness practices, Oregano Essential Oil, native to Mediterranean region, is steam distilled from the leaves and flowering tops of the herb It has a strong, spicy, and herbaceous scent with warm undertones.
Oregano essential oil is celebrated for its strong antimicrobial and immune-supporting qualities. It’s also a natural antioxidant, helping to protect the body from oxidative stress, and offers relief from congestion and minor aches.
Diffusing essential oils will deter many common indoor pests
- Add a few drops to a diffuser to create a peaceful, meditative atmosphere.
- Dilute with carrier oil for use in massages or skincare applications.
- Combine with Epsom salts and other relaxing oils for a deeply calming bath soak.
How to Use Essential Oils for Pest Control
When it comes to organic gardening, prevention is better than cure, and spraying crops regularly with essential oils to prevent insect infestation and disease is the most effective method. This will not only chase pests away, but also make your garden smell great!
Always use pure essential oils, and because they are so potent, always dilute them first.
How to dilute essential oils
One of the drawbacks of using essential oils in the garden is that the levels of terpenes and other constituents can vary greatly depending on the region where the plants are grown, genetics, climate and other seasonal factors. Therefore, maintaining consistency in the chemical profile of the oils is hard.
For example, Rosemary oil extracted from plants growing in two different regions of Italy will contain varying levels of α-pinene, ranging from 11% to 36%. Another study showed that essential oils extracted from different chemotypes of garden thyme did not have the same toxicity against the bean weevil.
This is the reason why, if you look for exact recipes for the oil you wish to use in the garden, you will find many different quantities of oil versus water used.
Another factor to take into account is the actual number of drops in a milliliter can vary greatly depending on the thickness of the liquid: Thicker liquids like essential oils produce larger drops, meaning it takes fewer drops to make 1mL. Different dropper bottles or droppers also have varying nozzle sizes, which changes the volume of a single drop.
In standard pharmaceutical measurements, 1 mL is equal to approximately 20 drops (meaning 1 drop is about 0.05 mL). Therefore, 10 drops are typically equal to about 0.5 mL.
This is why physicians do not rely on counting drops, as this can lead to incorrect dosing. Instead they use an oral syringe, a graduated measuring cup, or the specific dropper provided with the medicine.
CAUTION:
Because the actual number of drops in a millilitre can vary greatly depending on the thickness of the liquid and varying nozzle sizes, which changes the volume of a single drop, I recommend starting with the lowest recommended dosage. You can always increase it later.
Preventative Spraying
A general guideline when mixing sprays to deter insects, and for anti-fungus protection is to mix 4–8 drops of Essential Oil in 1 Litre of water with an emulsifier.
Garden Sprays
At certain times of the year various pests and diseases will be more prevalent, so for stronger protection dosages can be increased.
Generally you will find recommended dosages are between 10-20 drops per Litre of water.
Always Test Sprays First
Unless you apply very high doses of essential oils, they are perfectly safe to use in the garden. However, because the strengths of essential oils vary, to ensure they do not cause leaf burn, it’s important to always test your spray on a small, isolated area of the plant first. Wait at least 24 hours to check for damage before applying it everywhere.
A good method of remembering which leaves you tested your spray on is to tie string or ribbon onto the stems that have been sprayed.
Take Notes
Taking note of which plants were tested and the dosages used, will soon give you a good indication of the strengths your plants need for protection.
Mixing your spray
The Emulsifier:
Soap is essential as an emulsifier as essential oils do not mix with water and will float to the top, potentially burning your plants. A gentle liquid dish soap, pure liquid Castile or Black soap can be used.
Approximately one teaspoon of liquid soap emulsifier is used in one litre of water. Witch hazel, Vodka, or apple cider vinegar also emulsifies oil and water.
The Method:
In a small glass container, mix your essential oils with your emulsifier, then add some of the water and stir well. Warming the water helps with emulsification. Add the oil mix to the spray bottle with the rest of the warm water. Agitate well and also regularly whilst spraying.
Applying your Oils
Spraying in the middle of a hot, sunny day can cause leaf burn, so always apply the mixture in the cool of early morning or late afternoon. Remember to agitate the spray bottle well before use, and regularly while spraying. Ensure that you spray underneath the leaves where insects commonly hide.
During the cooler times of the day beneficial daytime pollinators are not that active. Never spray plants if you can see beneficial pollinators like bees around the plants. Even organic sprays can be abused in the garden, so as they say “everything in moderation”.
NOTE: The strength of the oils will evaporate, so reapply to plants after rain, every 2 weeks, or as needed.
Cotton Ball Method
To target specific insects in large numbers, like ant hills or rodent burrows, take some cotton balls and add a few drops of essential oils to them. Place the cotton ball right onto the ant hill, burrow or other insect grouping. This will cause them to relocate immediately. If that doesn’t work immediately you should repeat the process using a stronger solution.
You can also rub the oils onto any hard surfaces to create a long-lasting barrier.
Hanging Strips to Deter Pests
Add essential oils to a bowl of warm water and soak strips of pretty material or ribbon in the water before hanging onto the branches of fruit trees, or near edible gardens and ornamental shrubs.
Is there a waiting period before harvesting?
You should not eat vegetables and fruits immediately after spraying them with essential oils. These oils are highly concentrated and consuming them without a waiting period or proper cleaning can cause digestive upset, inflammation, or irritation of the mouth and oesophagus.
Essential oils degrade in sunlight and waiting 24 hours should be sufficient. Ensure that you always wash your food well and all will be fine.
Storing Essential Oil Mixes
Try to mix up only sufficient spray to use in a day, or within 24 hours of mixing. Once exposed to water and oxygen, oil-based garden sprays begin to separate, degrade, and lose their effectiveness.
If you do have any left-over, store it in a glass bottle in a cool, dark place, not in your plastic spray bottle, as essential oils break down quicker in plastic. Agitate well before using again.
