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!
Tea Tree Lemon Essential Oil
Lemon-scented Tea Tree Essential Oil (Leptospermum petersonii), a native of Australia, is steam-distilled from the leaves of the tree. It has a clean, lemon-like aroma that is both refreshing and calming, offering a unique combination of uplifting and purifying qualities. It’s clear to pale yellow colour and thin consistency make it a top note that blends well with other citrus, herbaceous, or woody oils.
Commonly used in natural cleaning products and air-purifying blends, it is also valued for its antimicrobial and insect-repelling properties indoors.
In the Garden
Geranyl acetate, γ-terpinene, geraniol, terpinolene, α-pinene, p-cimene, and linalool are the main components in Leptospermum petersonii Essential Oil. Research shows it acts primarily as an insect Repellent, Ovicide (egg deterrent), and Larvicide.
Leptospermum petersonii has scientifically documented fungicidal and antifungal properties, and research has demonstrated its effectiveness against various plant and human pathogens
Its active compounds act as microbial cell membrane disruptors, and nerve toxins in insects, reducing the number of eggs they lay. These volatile compounds in the oil exhibit strong insecticidal and mortality effects against many agricultural pests.
Because lemon-scented tea tree essential oil is a natural, plant-derived extract, it is biodegradable and often compatible with Integrated Pest Management (IPM) programs. For example, studies suggest that while the oil targets pests, it remains relatively harmless to beneficial biocontrol agents like egg parasitoid wasps.
Fungicidal and Antifungal Properties
Leptospermum petersonii has scientifically documented fungicidal and antifungal properties, and research has demonstrated its effectiveness against various plant and human pathogens. Its essential oil is highly effective at inhibiting the growth of, and directly destroying various fungi, largely due to its high concentration of volatile compounds like citral, neral, and geranial. Its volatile components aggressively disturb and degrade the fungal cell membrane, ultimately leading to cell collapse and death. Unlike many treatments that require direct physical contact, even the vapours of the oil are highly antifungal.
Crown and Root Rot of Apple Trees (Phytophthora cactorum)
The essential oil of Leptospermum petersonii shows good antifungal activity against crop-threatening pathogens like Phytophthora cactorum, a significant soil-borne pathogen that causes Crown and Root Rot, Collar Rot, and Die-back in mature apple trees.
First identified in South Africa in 1973, it is widely distributed throughout apple-producing areas but is particularly prevalent in our largest apple producing regions of the Western Cape, thriving in the mild and wet winters. Additionally, research conducted at Stellenbosch University has linked Phytophthora cactorum to Apple Replant Disease.
Research has demonstrated that, when vaporised, the volatile compounds of lemon-scented tea tree essential oil exhibits significant antifungal activity against the pathogen and inhibits growth. The oil works primarily in the vapour phase by directly disrupting the fungal cell wall and inhibiting mycelial development.
Red Spider Mite, Two-spotted Spider Mite (Tetranychus urticae)
Research shows that the essential oil has acaricidal effects and can be used to manage red spider mite populations. These mites are widespread in South Africa, and considered to be the most common and destructive spider mite species in the country. They cause significant damage across a wide range of Agricultural Crops, Indoor Houseplants, and Ornamental Plants.
Red spider mites attack over 1 200 host plant species, of which more than 150 are economically significant, and in South Africa they are a severe agricultural pest for Citrus, Table Grapes, Tomatoes and Cotton.
They thrive in warm weather, and in greenhouses the rate of damage is high throughout the year. The mites feed by sucking sap from plant cells, leaving pale, stippled spots that can eventually lead to leaf drop, stunted growth. They produce silk webbing that is easily visible when populations of this pest are high.
The essential oil of lemon-scented tea tree possesses properties that can be effective against the red spider mite, as the oil is rich in active compounds like citral (geranial and neral), which act as microbial cell membrane disruptors and nerve toxins in insects. Research indicates that the volatile compounds exhibit strong insecticidal and mortality effects against many other agricultural pests, while also reducing the number of eggs they lay.
Diamondback Moth (Plutella xylostella)
This moth is widespread in South Africa and is considered the most destructive insect pest for the family Brassicaceae, affecting crops like Cabbage, Canola, Broccoli, and Kale. The moth thrives year-round in South Africa’s mild climate, and its larvae can cause significant yield losses. Because the larvae feed under the leaves, creating translucent “windows”, they are notoriously difficult to control with traditional spraying.
The efficacy of lemon-scented tea tree oil, evaluated against the Diamondback Moth under laboratory conditions, showed that feeding activity and development of larval stages were significantly reduced on broccoli leaves that had been dipped in the essential oil. The laying of eggs was also deterred when the adults were exposed to treated leaves.
Potato Tuber Moth (Phthorimaea operculella)
This moth is a major agricultural pest in South Africa. It has been present in the country for more than 130 years and can be found in all nine potato-producing provinces. In South Africa it is particularly problematic during hot years and in areas with low rainfall.
While the Potato is its primary target, it also attacks Tobacco, Tomatoes, Peppers, and Eggplants The larvae damage both foliage and tubers, and the most severe damage occurs at the end of the growing season when larvae burrow into the soil to attack the potato tubers.
Studies have demonstrated the efficacy of lemon-scented tea tree essential oil as a botanical insecticide against agricultural pests, like the potato tuber in Integrated Pest Management (IPM), and monitoring with pheromone traps.
It works by reducing larval feeding activity, inhibiting larval growth, and significantly deterring egg-laying.
As an Insect Repellant
The oil contains active volatile components such as citronellal, geraniol, and citral, making it a highly effective natural alternative to citronella or lemongrass for deterring Mosquitoes and other insects.
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.
In the Home
Lemon-scented tea tree essential oil is bright and citrusy, and steam-distilled from the leaves of Leptospermum petersonii, a native of Australia.
With a clean, fresh, lemon-like, and lightly sweet aroma that is both refreshing and calming, this essential oil offers a unique combination of uplifting and purifying qualities. Commonly used in natural cleaning products and air-purifying blends, it is also valued for its antimicrobial and insect-repelling properties.
It’s clear to pale yellow colour and thin consistency make it a top note adds brightness and zest to blends using other citrus varieties or herbaceous woody oils.
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.
