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!
Thyme Red Essential Oil
Red Thyme Essential Oil (Thymus vulgaris), native to the Mediterranean region, is a warm, herbaceous and spicy oil, steam-distilled from the leaves and flowering tops of responsibly grown Mediterranean thyme. Known for its clear to reddish-brown colour and thin consistency, this essential oil carries a robust aroma prized in traditional and modern herbal medicine.
In the Garden
Thyme essential oil has emerged as a potent botanical insecticide due to its rich composition of bioactive compounds, particularly thymol, carvacrol, p-cymene, and linalool, which contribute significantly to its Insecticidal efficacy. The oil demonstrates strong Fumigant and Contact Toxicity.
Researchers are still studying the Insecticidal, Repellent, and Growth-inhibitory properties of thyme essential oil against economically significant insect pests. Because it is rich in thymol and carvacrol, which disrupts the cell membranes or metabolic processes of insects, it exhibits Antifeedant, and Oviposition Deterrent activities which prevent the insects from laying eggs on plants, reducing reproduction. It also works by suffocation, blocking the breathing tubes (spiracles) of small insects and mites. The oil also suppresses critical detoxifying enzymes in insect larvae.
Its efficacy, combined with its biodegradability and low toxicity to non-target organisms, highlights thyme essential oil as a sustainable alternative to synthetic insecticides, and its integration into eco-friendly pest management strategies, promoting safer agricultural practices and minimizing environmental impact.
Thyme essential is a highly effective insecticide indoors and repels Houseflies. A 2005 study also found it to be an excellent Mosquito Repellent.
Thyme oil is also effective against various Fungal Pathogens like Botrytis, also known as Grey Mold, and Cercospora Leaf Spot. Thyme essential oil acts as a defence inducer of Tomatoes against Grey Mold and Fusarium Wilt.
Red thyme essential oil is used in organic and conventional farming as a Broad-spectrum Spray in commercial formulations like Thyme Guard, to control Soft-bodied Insects, Mites, and Fungal Diseases.
Extensive laboratory investigations have demonstrated that the essential oils have strong Ovicidal, Larvicidal, and Adulticidal activities against a range of economically important pests, including:
Armyworms
The African Army Worm and the invasive Fall Armyworm are the two major species causing significant Agricultural and Grassland damage across multiple provinces in South Africa.
Research shows that thyme essential oil impacts armyworms and related caterpillar pests by acting as a natural insecticide, deterrent, and enzyme disruptor. It provides moderate to high larval toxicity, reduces feeding, and inhibits critical internal metabolic processes.
The essential oils primary active constituent, thymol, disrupts insects’ neuromodulation and blocks breathing structures, causing direct larval mortality. Whole thyme essential oil is often more toxic than its isolated components because of synergistic interactions among minor compounds.
Thyme essential oil reduces crop damage by the caterpillars by suppressing appetite and causing starvation.
African Armyworm (Spodoptera exempta)
A native of Africa, the African Armyworm is famous for sudden mass swarming and marching behaviour. It frequently attacks Lawns, Pastures, and Grain Crops in high-rainfall regions.
Fall Armyworm (Spodoptera frugiperda)
This invasive pest was first detected locally in 2016-2017. It attacks crops day and night, preferring Maize, Sweetcorn, and Sorghum.
Lesser Armyworm (Spodoptera exigua)
Lesser armyworm spreads readily, affecting various Vegetable and Flower Crops. Outbreaks and populations occur across Limpopo, Mpumalanga, North West, Free State, Gauteng, and KwaZulu-Natal. They target Maize, Sorghum, Soybeans, Potatoes, and Grazing Pastures. Severe infestations often follow specific weather patterns like early summer rain, and mid-summer dry spells.
Lesser Mealworm, Litter Beetle (Alphitobius diaperinus)
This beetle is widely believed to have originated in sub-Saharan and southern Africa before spreading globally as a cosmopolitan pest. It is frequently found in agricultural areas, particularly in Poultry Broiler and Layer Facilities, where it thrives in deep-litter bedding, manure, and spilled feed.
It acts as a generalist pest in Livestock and Poultry houses, and can damage the insulation and structure of agricultural buildings when the larvae tunnel to pupate. It also serves as a vector and reservoir for various animal pathogens like Salmonella and Escherichia coli.
The insecticidal activity of Thymus vulgaris essential oil, thymol and carvacrol, was evaluated in a laboratory against different larval stages of lesser mealworm. Results showed that thymol and carvacrol alone could effectively control this pest. Therefore, thymol and carvacrol show potential as an alternative to chemical controls and can be incorporated into Integrated Pest Management (IPM) to control this pest.
African Bollworm, Cotton Bollworm, Corn Earworm, Tomato Grub (Helicoverpa armigera)
Thyme essential oil is affective at controlling the African or Cotton Bollworm. This indigenous pest occurs widely in South Africa and is a major agricultural pest affecting numerous Field Crops, Vegetables, and Fruits. It impacts crops like: Cotton, Maize, Sorghum, Sunflowers, Soybeans, Dry Beans, Tomatoes, Sweet Corn, and various other Garden Vegetables, as well as Deciduous and Subtropical Fruit like Apples and Citrus.
Cotton or Melon Aphid (Aphis gossypii)
The cotton or melon aphid occurs in South Africa, where it is found across all provinces. It is an active agricultural and forestry pest that impacts host plants and crops like: Cotton, Citrus, Potatoes, and Cucurbits like Melons and Cucumbers. In forestry it infests young Eucalyptus trees in commercial plantations, spreading plant viruses and causing leaf curling and stunted growth.
Grey Mold and Fusarium Wilt
Thyme essential oil acts as a defence inducer of Tomatoes against grey mold and fusarium wilt
The potential of thyme essential oil in controlling gray mold and Fusarium wilt and inducing systemic resistance in tomato seedlings and tomatoes grown in a hydroponic system was evaluated.
Studies revealed that thyme essential oil reduced 64% of Botrytis cinerea colonization on pre-treated detached leaves compared to untreated control. Also, it played a significant decrease in Fusarium wilt severity especially at 7 days post treatment when it was reduced to 30.76%.
Plant response observed either after foliar spraying or root feeding in hydroponics showed that thyme oil seems to be more effective when applied to the roots.
Sitophilus species
Sitophilus species like the Maize Weevil and Rice Weevil are widespread agricultural and storage pests in South Africa.
Maize Weevil (Sitophilus zeamais)
This is a major pest of stored maize and cereals, and is common in warm regions like Limpopo, Mpumalanga, and KwaZulu-Natal.
Rice Weevil (Sitophilus oryzae)
This cosmopolitan stored-grain pest found across South African grain-handling and storage facilities.
Granary Weevil (Sitophilus granarius)
This weevil is recorded in stored wheat and cooler climate grain stocks
Cercospora Leaf Spot (Cercospora beticola)
The fungus Cercospora beticola is the most dangerous pathogen of Sugar Beet and the causal agent of leaf spot, which occurs in South Africa on crops like Beetroot and Swiss Chard. This pathogen is a necrotrophic fungal parasite which is an organism that actively kills its living host’s cells using toxins and enzymes before feeding on the resulting dead tissue
Symptoms show as small circular spots with ash-grey centres, and dark purple or brown borders. It damages leaves, reduces yields, and threatens local commercial vegetable production. The pathogen thrives in warm ranges between 25°C and 30°C, and when humidity is relatively high, or when the leaves are wet for a prolonged time.
Studies confirmed that thyme essential oil can effectively limit the growth of Cercospora beticola both in plate tests and field cultivation of sugar beet. Moreover, it also limited the growth of resistant fungal isolates. The results indicate that thyme essential oil may be a promising method for the protection of sugar beets, although it requires further optimization in the context of its inclusion in sustainable protection programs.
Garden Spray
Thoroughly coat the top and underside of all leaves where pests hide. Reapply the spray every 2 to 3 days to prevent diseases and repel pest. Reapply until the problem completely clears.
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 or surfaces.
In the Home
Red Thyme Essential Oil (Thymus vulgaris), native to the Mediterranean region, is a warm, herbaceous and spicy oil, steam-distilled from the leaves and flowering tops from responsibly grown Mediterranean thyme. Its middle note perfume adds herbal warmth and depth to blends.
Therapeutic Properties:
Thyme, Red essential oil is valued for its broad wellness applications, including:
- Antimicrobial: Effectively combats bacteria, fungi, and other pathogens
- Stimulating: Enhances mental clarity and boosts energy
- Respiratory Support: Helps clear airways and promote easy breathing
- Digestive Aid: Supports digestion and relieves discomfort
- Skin Nourishing: Promotes healthy and vibrant skin
When diffused indoor the essential oil will deter many household 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.
