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!
Spearmint Essential Oil
Spearmint Essential Oil (Mentha spicata), a member of the Lamiaceae family native to Europe and Asia, is a refreshing, sweet, and minty oil steam-distilled from the leaves of sustainably cultivated spearmint plants. With a softer, sweeter aroma than Peppermint, Spearmint oil is often used to support digestion, enhance energy, and promote respiratory health.
In the Garden
Spearmint essential oil is a highly effective, eco-friendly bio-pesticide capable of repelling, harming, or killing a broad range of garden and agricultural pests, stored-grain insects, and disease vectors. It primarily impacts insects through oral toxicity, starvation, or direct fumigation.
Unlike synthetic alternatives, essential oil is fully biodegradable and does not persist toxically in the soil or waterways.
Acute toxicity screenings reveal that standard exposure levels are completely harmless to mammals and non-target organisms.
Studies show that field applications do not alter the vital survival characteristics of critical predatory insects, making spearmint essential oil perfect for Integrated Pest Management (IPM) programs.
Spearmint essential oil bypasses the need for harsh synthetic chemicals through several biological pathways:
Enzyme Inhibition
It significantly inhibits acetylcholinesterase (AChE) within insects. This blocks the breakdown of vital neurotransmitters, leading to neuromuscular overstimulation and death.
Driven primarily by its main active chemical constituent carvone which disrupts the insect’s vital neurotransmitters, leading to neuromuscular overstimulation and death, while remaining safe for mammals and many beneficial predatory insects. The oil also acts as a powerful antifeedant, reducing pests’ relative growth and consumption rates.
As a Repellent
The strong volatile aroma overloads insect’s sensory systems, causing high adult repellence and completely inhibiting pests from laying eggs on treated crops.
Pests it Targets
Research demonstrates that Mentha spicata oil is highly versatile across distinct pest categories.
Stored-Grain Protection
Spearmint essential oil provides exceptional fumigant toxicity against devastating warehouse and grain silo pests like the Cowpea Weevil and the Rice Weevil.
When applied directly to seeds and grains(such as chickpeas, the oil acts as an antifeedant and oviposition, a chemical or physical cue that significantly reduces the egg-laying ability of stored-product pests.
Cowpea Weevil (Callosobruchus maculatus)
The cowpea weevil is a widespread and major storage pest in South Africa. Despite its name, it is not a true weevil but rather a type of leaf beetle (seed beetle) that specifically targets stored legumes.
The beetles originate from Africa and occur throughout the country, frequently infesting Cowpeas like Black-eyed Peas and other Dried Legumes like Lentils and Chickpeas.
Cowpea weevils are considered the most important source of post-harvest loss for grain merchants and farmers in South Africa. The adults do not eat the seeds, they lay eggs on them, and the emerging larvae tunnel into the beans, eating the endosperm, and ultimately emerging through round “window” holes.
Rice Weevil (Sitophilus oryzae)
The rice weevil is widespread in South Africa and is frequently found nationwide in grain storage facilities, pantries, and food processing plants, where they infest stored Rice, Maize, Wheat, and other dry Cereals.
These small reddish-brown beetles have an elongated snout and four faint yellowish or reddish spots on their wings. Adult females use their snouts to drill into a single grain, lay an egg, and seal it. The larva eats the inside of the grain, leaving behind hollow, powdery shells.
Weevil Control: Discarding any infested packages and prevent infestations by inspecting dry goods before purchasing, and store in airtight, insect-proof containers.
Mosquito & Vector Control:
Studies demonstrate that spearmint essential oil, particularly in advanced nano-emulsified forms, acts as a potent larvicide against Culex and Aedes Mosquitoes, as well as Houseflies, making it highly valuable for vector control without harming mammals.
Mosquitoes and Houseflies
When formulated into micro or nanoemulsions, spearmint essential oil exhibits enhanced water solubility and achieves high larvicidal activity against Mosquitoes (Culex pipiens) and Houseflies (Musca domestica).
Mosquitoes (Culex pipiens)
Culex pipiens is widely distributed across South Africa, though in many local regions it largely thrives alongside the closely related Culex quinquefasciatus, which is more commonly found in the sub-tropical and tropical regions of Africa.
These mosquitoes are known vectors for several important arboviruses, including West Nile Virus and Rift Valley Fever, and they tend to thrive in urbanized environments and areas with standing water.
Spearmint essential oil works as an active larvicide, stopping mosquito larvae from maturing in standing water.
Houseflies (Musca domestica)
Musca domestica, commonly known as the housefly, is widespread across the country, thriving in both rural and urban areas where human activity provides food, waste, and favourable breeding conditions.
In South Africa, houseflies are frequently encountered around homes, restaurants, food markets, and livestock farms like poultry and pig farms. The warmer, wetter conditions during the summer create ideal breeding environments for them.
Because these flies frequently interact with both waste and human food, they are recognized by the KZN Department of Health as major mechanical carriers of disease-causing pathogens.
Destroyer Ants (Trichomyrmex destructor)
Destroyer ants are highly destructive urban pests notorious for causing costly damage to electrical equipment. These ants are strangely attracted to the warmth and electromagnetic fields around live electrical currents. When foraging workers enter switchboards, wall sockets, or appliances, one ant is often electrocuted. Its dying body releases a formic acid pheromone that calls in thousands of nest mates to “attack” the perceived threat, quickly forming carbonized bridges that fry circuits and completely destroy electrical components. They are particularly prevalent in Gauteng where they frequently chew into appliances, gate motors, and pool pumps.
Destroyer Ants, often called Singapore Ants or Destructive Trailing Ants are very small, about 1.5 to 3mm in length, and vary in colour from pale yellow to reddish-brown. Unlike common sugar ants, they possess a modified stinger used to spray venom and can deliver a painful bite.
Baiting the Colony:
Because destroyer ants have omnivorous diets, slow-acting, protein-or fat based toxic baits (like a mixture of boric acid and peanut butter) or bacon grease work best. Foragers carry the poisoned bait back to the nest, wiping out the colony and queen.
Natural Repellents:
If you have children and pets around a prefer a non-toxic alternative, research shows that essential oils derived from spearmint, lemongrass and rosemary are highly toxic to and effectively repel destroyer ants. It has been proven to cause 90% mortality in destroyer ant populations when applied directly.
Other Pests
Spearmint essential oil acts as a potent fumigant and insecticide against adult Moths, and is proven to control Whiteflies, and Red Spider Mites. It also helps repel other common soft-bodied pests like Aphids and Thrips from your garden.
While it may not instantly kill these pests on contact, it inhibits their ability to settle on leaves and irritates mites enough to reduce their feeding.
Fungal Plant Pathogens
Spearmint essential oil acts as a powerful fungicide, showing up to a 100% inhibition rate against agricultural moulds like Fusarium oxysporum and Alternaria citri.
Formulation Developments
While highly effective, raw essential oils evaporate quickly. To maximize field stability and prolonged performance, researchers heavily utilize nanotechnology. Encapsulating Mentha spicata oil into chitosan nanoparticles creates a controlled-release mechanism that protects the active compounds from heat and UV degradation, extending its protective lifespan by days or weeks.
Alternaria Brown Spot, Black Rot, Core Rot (Alternaria citri)
The fungus Alternaria citri affects the inside of citrus fruit, causing dark leaf spots and lesions on the peel. It is a widespread pathogen in South Africa’s citrus-producing regions, threatening susceptible cultivars like Minneola Tangelos and Mandarins.
Fusarium Wilt (Fusarium oxysporum)
This soil fungus occurs widely in South Africa, both as a naturally occurring soil fungus in native ecosystems like the grassland biome, and as an economically damaging plant pathogen.
The pathogen affects a wide variety of crops and plant species across the country, with distinct variants causing specific diseases.
Banana Panama Disease (Fusarium oxysporum f. sp. cubense)
Panama disease was initially reported in KZN in 1940, and remains persistent in two of South Africa’s six major banana-producing regions, Kiepersol in Mpumalanga, and southern KwaZulu-Natal.
Unlike the notorious and highly destructive Tropical Race 4 (TR4) that has devastated Cavendish crops globally South African plantations have largely been affected by Subtropical Race 4 (STR4), which attacks the plants primarily under environmental stress or cooler subtropical conditions.
Fusarium Wilt of Tomato (Fusarium oxysporum)
Mentha spicata essential oil can control Fusarium wilt of tomato. Research shows its active compounds like menthol and menthofuran can significantly inhibit fungal mycelial growth of strains such as: Wilt (Fusarium oxysporum f. sp. lycopersici) and Crown and Root Rot (Fusarium oxysporum f. sp. radicis-lycopersici).
Potato Fusarium, Fusarium Dry Rot
Fusarium rot is a predominant species driving tuber decay and dry rot of tubers during storage, and destroys seed pieces after planting. It is caused by various Fusarium species such as (Fusarium solani) and (Fusarium sambucinum). The disease results in massive postharvest yield losses.
Spearmint essential oil shows promise in suppressing the fungi that cause Fusarium potato dry rot, because it contains active volatile compounds like menthol, carvone, and menthone, which possess strong natural antifungal properties. However, its practical effectiveness as a standalone treatment varies significantly depending on application methods and fungal strains.
As an Anti-sprouting Agent
One major advantage of spearmint oil in potato storage is its proven ability to act as an anti-sprouting agent. It can protect stored tubers from sprouting while simultaneously combating pathogenic fungal growth.
Comparison with other essential oils
While spearmint essential oil is proven to be effective, some studies note that other essential oils like cinnamon, oregano, thyme or palmarosa can sometimes offer higher levels of fungal inhibition against certain strains of Fusarium.
Sweet Potatoes (Fusarium oxysporum f. sp. batatas)
Fusarium wilt on sweet potatoes is a destructive fungal disease that is widespread in South African sweet potato production areas, thriving in warm, wet soils, and remaining viable for many years. The pathogen blocks water transport in the plant, causing foliage to turn yellow, wilt, drop off, and eventually collapse.
Spearmint essential oil can inhibit the growth of Fusarium species like Fusarium oxysporum in sweet potatoes. However, scientific evaluations show that it is not highly effective at controlling the disease once it establishes on the crop.
Synergistic Power:
Mixing spearmint oil with other mint varieties significantly multiplies its toxicity against stubborn pests like termites due to compound synergy.
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 or surfaces.
Post-Harvest Protection
Fumigation
The essential oil can be introduced to sealed storage containers to deter pests and affect adult development without impacting the germination rate of legumes or cereal.
Protection
Add a few drops of pure oil to porous clay pucks or sachets and place them inside sealed storage containers. The released fumes safely repel beetles without diminishing seed viability or germination rates.
Impregnating storage bags with parsley essential oil has been studied as a tool to manage and repel crop-destroying insects without using harmful chemical residues.
The Cotton Wool Method listed below is also effective in pantries and small storage spaces.
In the Home
Sandalwood Essential Oil is richly aromatic and steam-distilled from the heartwood of the sandalwood tree, traditionally grown in India and other parts of Southeast Asia. Our essential oil is sourced from responsibly harvested or cultivated sandalwood to support long-term ecological balance.
Prized for centuries in both perfumery and spiritual practice, Sandalwood is known for its warm, woody, and creamy aroma that promotes deep calm and emotional grounding. Its thick consistency and long-lasting scent make it a revered base note in aromatic blends.
In skincare and wellness, it is favoured for its anti-inflammatory, antimicrobial, and mood-balancing properties and is commonly used for meditation and in relaxation blends, perfumery, and in skincare for dry or inflamed skin.
When diffused indoors essential oil with keep many household pests away.
- 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.
