Top 10 DIY Organic Pest Control Remedies

BY RICH HAMILTON

Hungry pests, diseases, and deficiencies are, unfortunately, inevitable in the garden. There are many ways to help control them, but most are far from natural. What options are there for growers wanting to maintain a purely organic environment? Here’s a look at the best do-it-yourself methods available, all of which are inventive, easy on the wallet, and environmentally-friendly!

Capsaicin

Capsaicin is what gives hot peppers their heat. Produced by pepper plants to repel insects and animal predators, this is an ideal all-natural pest control weapon for other plants.

Cayenne pepper contains capsaicin and can repel ants when sprinkled as a powder. You can also make an insecticidal pepper spray using dried fresh hot peppers, vegetable oil, lecithin, and water.

Mix 1/2 tablespoon of the spray concentrate with one pint of water and test spray onto a few leaves.

Wait 24 hours to be sure the potent spray doesn’t cause any damage before applying to the rest of the plant.

PRO TIP: When growing indoors, it is best to use foliar sprays when the lights are off.

Castor Oil

Moles and gophers despise the smell and taste of castor oil. Smear the oil onto some paper and drop into their tunnels or burrows. Alternatively, you can place the oil strategically at the borders of the garden.

Applying castor oil directly to the soil will work for a week or so, even in the rainy season.

Use a hose-end attachment and spray a mixture of two tablespoons per gallon of water evenly to the affected areas. Treating with castor oil weekly will result in fewer molehills and dug up garden beds without any danger to pets, children, or the environment.

Cinnamon Oil

With an effectiveness rate of 50-70%, cinnamon is excellent for reducing and controlling powdery mildew. Cinnamon is also a useful tool for battling ants, aphids, fungus gnats, spider mites thrips, and whiteflies.

Add 5ml of oil to 950ml of water, or make a tea by adding an ounce of cinnamon to 1.5 pints of boiling water.

Let the tea cool then add half a pint of rubbing alcohol. Strain the mixture and spray directly on to the leaves.

PRO TIP: For a quick fix against ants, sprinkle the cinnamon powder onto any area of the garden you see them crawling.

Vinegar

An old housewive’s favourite with many uses in and around the home, vinegar kills powdery mildew and can also help deter ants.

Use as a spray and dilute it at a rate of 15ml vinegar per litre of water.

With a 5% acetic acid level, household white vinegar also works as a natural herbicide against weeds. However, while it does burn the tops of the weed and temporarily destroys them, it does not have any effect on the root system and will not eradicate the problem permanently. Vinegar will also kill the foliage of any other plants it comes into contact with, so use carefully!

Coriander Oil

Coriander oil acts as a fungicide and insecticide and can control Pythium, grey mould, Fusarium, powdery mildew, Septoria, aphids, thrips, spider mites, and whiteflies. The coriander plant is also an excellent pest deterrent plant for indoor growers.

Make an oil spray by mixing one teaspoon of oil per pint of water with some lecithin and a wetting agent.

Alternatively, make a simple spray with fresh coriander. Use one part coriander plant with equal parts of water. Boil the coriander for ten minutes, cool, strain and spray.

PRO TIP: Increase the effectiveness of your spray by adding ingredients to make it stick better to its target. Coconut oil, used at 5ml per litre of spray, is an active spreading agent.

Clove Oil

Eugenol, a component of clove oil, works as a fungicide and a contact insecticide with a lingering smell. Clove Oil is effective against Pythium, grey mould, Fusarium, ants, caterpillars, thrips, aphids, and spider mites.

Clove oil can also keep some healthy species away, so spray only in the areas where you are experiencing problems.

To keep moles and other rodents at bay, place a few drops of clove oil in the holes or runs they've made for themselves. If oil alone doesn't work, try crushed, dried clove leaves. When dried cloves or clove oil is ingested, it numbs the mouth, keeping rodents away without killing them.

To make clove oil spray, pour ten drops of clove essential oil into a spray bottle. Fill up with water and shake well. Exposure to light may decrease the efficacy of clove oil, so it is best sprayed when the garden is not in direct sunlight, or when the lights are off if growing indoors. PRO TIP: Rub clove oil around the rim of your plant pots to deter thrip in an indoor growing environment.

Milk

The properties that make milk good for humans, such as calcium and B vitamins, also benefit plants. Calcium helps plants grow and prevents deficiencies such as blossom end rot, a condition common in tomato, peppers, and squash plants.

Milk can also be used as a pesticide against aphids and as an anti-fungal agent to prevent powdery mildew and mosaic leaf viruses. Milk is so efficient at killing powdery mildew that rose growers all over the world use it as a fungicidal spray.

Using too much milk, however, can damage your plants. The natural bacteria present in the dairy product can stunt growth and cause wilt. The fat in whole milk can cause a foul odour, while skimmed milk could lead to black rot, soft rot, and Alternaria leaf spot on certain crops. If growing indoors, make sure the ventilation system is fully operational, as the above issues can escalate very quickly.

Make a milk spray by using one part milk to nine parts water. Avoid possible issues by using 1% fat milk. Use at the first sign of infection and then once a week to protect new growth.

Limonene

Limonene is the refined oils from the rinds of citrus fruit. D-limonene (the main constituent of orange oil) is harmless to humans but deadly to most insects. It dissolves the waxy coating on the exoskeleton, causing dehydration and asphyxiation. Limonene can wipe out or repel entire colonies and prevents future infestations in one application. It is most effective against ants, aphids, fungus gnats, mealybugs, scales, spider mites, and whiteflies.

To make limonene spray, remove the white, inner portion of the orange or lemon rinds and cut into small pieces. Bring the rind pieces to a boil in a pan of water, then turn down the heat and simmer for five minutes.

Remove from the stove, cover with a lid, and allow to soak for 24 hours. Then, strain and pour into a spray bottle. The solution can be applied directly onto soft-bodied insects, such as aphids and fungus gnats.

PRO TIP: Limonene oil is so effective at killing bugs that it can also kill beneficial bugs and pollinators, so apply minimally and only where necessary. If growing indoors, this must be sprayed at lights off.

Garlic

Anti-fungal and anti-bacterial, garlic works on ants, aphids, caterpillars, spider mites, thrips, and whiteflies. Garlic is also effective at destroying fungi and powdery mildew thanks to its high sulfur content. Great as a preventative spray, it can be used on new growth to keep problems from arising.

Make a garlic spray by using a teaspoon of garlic oil in one pint of water. Mix with two ounces of high percentage alcohol spirit like Vodka.

PRO TIP: Use garlic as a companion plant in your garden. The strong odour is repulsive to many pests, and so inter-planting garlic with carrots, brassicas, peppers, tomatoes, and eggplant can help deter many insects and rodents.

Tomato leaf

Tomato plants are part of the nightshade family, and as such, contain toxic compounds called alkaloids in their leaves such as the aptly named "tomatine." Alkaloids make a very effective repellent that is toxic to aphids and other leaf-eating insects, but completely safe for humans and beneficial bugs like bees and ladybirds.

To make a tomato leaf spray, chop 500g of fresh tomato leaves taken from the bottom part of the plant and add to 250ml of water. Let it steep overnight. Strain the plant material and spray onto plant foliage.

Many effective treatments can be made cheaply using everyday items. It’s safe and easier than you think!