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!
Rose Grapefruit Essential Oil
The essential oil of Rose Grapefruit (Citrus paradise), a native of Barbados, is cold pressed using the peel to preserve its delicate aromatic compounds.
In the Garden
It is already established that the essential oils of various citrus species are effective against a wide range of pests and pathogens. There are two compounds found in the peel and pith of citrus that are used as pesticides, namely limonene and linalool. These are low in toxicity and are generally safe for mammals. In fact, you can even find them in shampoos and dips for pets. The oil also has mild, natural fungicidal properties.
The Lesser Grain Borer (Rhyzopertha dominica)
Essential oils derived from citrus species have emerged as promising alternatives for pest management in stored food items, demonstrating effectiveness while offering safety and environmental benefits, as these oils are biodegradable and exhibit minimal toxicity to humans and beneficial organisms.
This Lesser Grain Borer is a cosmopolitan pest that thrives in warm countries, making it a widely established threat in stored grains such as wheat, maize, sorghum, and rice throughout South Africa. Both the adult and larval stages are highly destructive, and capable of tunnelling into healthy, undamaged kernels.
Results on studies done using the essential oil of Citrus paradisi against lesser grain borers was most effective, and even more effective than the oil from Citrus reticulata oil, showing the potential usefulness of citrus oils for the management of this pest in flour mills, warehouses and food storage facilities.
Rose Grapefruit Essential Oil is a highly effective, natural pest deterrent and larvicide in garden sprays, thanks to its high concentration of d-limonene. A larvicide is a type of insecticide specifically targeted to kill the immature, aquatic larval or pupal stages of insects before they develop into biting adults. They are most commonly used for Mosquito control but can also target other pests like Flies.
The limonene in grapefruit oil acts as a contact poison that disrupts the neurotransmitters in insects, causing hyperactivity and eventual death. The oil coats the exoskeleton of tiny insects like Mites and Aphids and smothers them, while its strong citrus scent deters other insects from returning.
It was found that both Ants and Mosquitoes species repel from the limonene.
Crickets
Grapefruit essential oil deters crickets through its strong aroma and active chemical compounds, primarily d-limonene and nootkatone. These natural elements overwhelm the insect’s senses and act as a contact irritant, making the environment inhospitable.
Crickets possess olfactory receptors on their antennae and body. The volatile molecules of the citrus oil mask environmental scents and confuse the cricket’s nervous system, preventing them from locating food or mates.
Crickets have taste sensors on their legs (tarsi) and mouthparts. When they walk over surfaces treated with the oil, the compounds trigger deterrent receptors, causing them to immediately flee the area.
The primary active constituent in grapefruit oil, d-Limonene, has been shown in studies to interfere with an insect’s detoxification pathways and nervous system, serving as a powerful natural botanical protectant.
House Crickets (Acheta domesticus)
The house cricket, while not native to the African continent, has become a widespread household pest throughout South Africa, and particularly in warmer, moist areas.
They are primarily active at night and heavily attracted to bright outdoor lights, commonly slipping into homes through gaps under doors and windows. The males produce the well-known, loud chirping sound to attract mates. They do not bite or destroy wooden structures, but can become a noise nuisance and occasionally damage stored textiles or paper.
Field Crickets (Gryllinae subfamily)
Field Crickets are native to South Africa and are very common. They are frequently found in gardens, lawns, and open disturbed areas, and they often wander inside for food and shelter. The most common field cricket species that enters homes and chirps irritatingly loudly is the Two-spotted Cricket (Gryllus bimaculatus).
Parktown Prawns
Often mistaken for crickets, these large, aggressive king crickets frequently wreak havoc on suburban gardens and wander into homes.
African Mole Crickets (Gryllotalpa africana)
These crickets are indigenous to South Africa, and well-adapted to the local environment. They are found naturally in moist soils near riverbanks, in damp lawns, and around agricultural areas.
These plump, yellowish-brown insects with shovel-like front legs live deep underground, tunnelling through the soil and chewing the roots of lawns and crops. While they are a beneficial part of the ecosystem, their tunnelling can sometimes cause damage.
If you are looking for mole crickets in your lawn, the most reliable detection technique is the soapy-water flush test. This method irritates their skin, forcing the crickets to the surface in just a few minutes.
Mix 1-2 tablespoons of liquid dish soap (avoid degreasers or bleach) with 4 Litres of water. Pour the mixture evenly over one square metre of lawn that shows signs of tunnelling or spongy grass. Wait 3-5 minutes. If present, mole crickets will crawl to the surface for air. If 2 to 4 mole crickets surface per test site, it indicates an infestation that requires treatment.
Spraying for mole crickets
Controlling mole crickets in a lawn can be hard because they tunnel down deeply, so timing is vital. Spray your lawn in the late afternoon or evening, as crickets are most active at night, and spraying later prevents the hot midday sun from evaporating the oil too quickly.
Use a Hose-End Sprayer: Mix 15-20 drops of grapefruit essential oil with 1 cup of water and a few drops of liquid dish soap inside the sprayer jar. Hook it up to your garden hose to evenly coat large grassy areas. Pay extra attention to areas with thick thatch, woodpiles, or lawn edges next to garden beds where crickets like to hide.
Unlike harsh chemicals, natural oils break down quickly in the elements, so you may need to spray again, and especially after a heavy rain or after mowing your lawn.
Biting Ants
In a study, grapefruit essential oils were used as fumigant agents to control red fire ants. It proved that grapefruit essential oil is a promising, eco-friendly, and safe fumigant for the control of red imported fire ants.
While the notorious mported Red Fire Ant (Solenopsis invicta) is absent from South Africa, local invasive fire ant species like the Tropical Fire Ant (Solenopsis geminata) are present.
Additionally, other aggressive stinging ants, such as the African Big-headed Ant (Pheidole megacephala) are widespread. This globally invasive species is considered one of the world’s 100 worst pests. Native to Africa, it is highly aggressive, displaces native invertebrates, and damages agriculture by protecting sap-sucking insects and chewing through electrical or irrigation wires.
Paper Wasps
Citrus paradisi essential oil and other citrus oils emit strong, volatile aromatic compounds that can overload a paper wasp’s scent receptors, effectively disorienting them and deterring them from nesting or lingering in treated areas.
Paper wasps construct distinctive umbrella-shaped, open-comb nests from chewed wood and saliva, often found under roof eaves, tree branches, and window frames. While they are generally non-aggressive, they will deliver a painful sting to defend their nests.
The South African Paper Wasp (Polistes marginalis) is common nationwide. They are mostly docile and beneficial garden predators that feed on aphids and caterpillars.
However, we also have an invasive species, the European Paper Wasp (Polistes dominula) which is considered a restricted Category 1b Invasive Alien Species in South Africa. It is highly concentrated in the Western Cape, especially in the greater Cape Town area, Hermanus, and Porterville, where it disrupts local ecosystems.
To tell the difference between the invasive European Paper Wasp (Polistes dominula) and native paper wasps like (Polistes africanus), or (Polistes marginalis) in South Africa, you need to look closely at their colour patterns and antennae.
The European paper wasp has a bold, high-contrast black and yellow pattern, resembling a classic yellow jacket. Native African species tend to have a more reddish-brown, dark, or orange body, often with bright yellow bands wrapping around the first few segments of the abdomen.
The European paper wasp features distinct orange to reddish-orange antennae. Native paper wasps typically have darker, almost entirely black or brown antennae. Both are medium-sized and slender, but the European wasp has a very narrow “waist”. If you see them flying, both native and European paper wasps have long legs that hang down noticeably beneath their bodies.
Garden Spray
Citrus oils are used to control pests like Aphids, Spider Mites, Mealybugs, Whiteflies, Scale, Mosquitoes, Fleas, Ants, Flies, Paper Wasps, and Crickets on contact.
Mix 15-20 drops of essential oil with 1 teaspoon if liquid soap as an emulsifier and add to 1 Litre of water. Agitate and spray.
Indoors and around patios etc. cotton wool balls soaked in the essential oil and tucked into vulnerable areas will deter many pests.
Fungal Management
The oil also provides mild natural fungicidal properties.
In the Home
Indoors, Grapefruit Rose Essential Oil offers a refreshing blend of bright, sweet, citrusy, and slightly floral with a hint of rose. Its top perfume note blends well with lavender, bergamot, geranium, and cedarwood.
This uplifting oil is a favourite in aromatherapy for emotional balance, skincare, and digestive support. Its unique floral twist pairs beautifully with other citrus, floral, and wood oils in personal care and diffuser blends.
If diffused it will repel many of the garden pests mentioned above.
- 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.
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.
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.
