How and When To Use Neem Oil On Cactus? [Step by Step Guide]

I have been using neem oil to prevent pests or fungal outbreaks in my cactus. If you haven’t heard of neem oil but would want to try it, let me share with you the basics.

Neem oil should be used on cactus to prevent and treat pests and insects by 1) direct spraying, 2) soil drenching, and 3) deep soaking. Neem oil should not be used on cactus 1) during extreme cold or hot temperatures, 2) cacti seedling, 3) newly repot cacti, 4) during midday, and 5) near ponds and beehives. The best time to use neem oil is during sundown.

Many agriculturists and home gardeners love the idea of using neem oil for their plants because it is organic and leaves very low residue on the environment. Let’s learn more about neem oil.

What Is Neem Oil?

Neem oil is an organic product extracted from the seeds of the Neem tree that are popular in India. The oil extract is opaque, yellow to brown, with an acrid odor that resembles garlic or sulfur. It is widely used in agriculture because of its natural ability to kill pests and repel insects.

Neem seeds are crushed and pressed to extract their oils. The final product is called crude or raw neem oil, and they are readily available in the market. It contains several chemical components, but the most active ingredient is the Azadirachtin.

Research has shown that azadirachtin is among the most potent substances that can disrupt pest growth and procreation. The extract was first reported to eliminate desert locusts in India in 1928.

In 1962, a field test conducted in New Delhi showed that some insects refused to eat crops sprayed with neem oil, while others were killed after consumption. Although detrimental to insects, neem oil is not toxic to pets and humans unless ingested.

How Does Neem Oil Work?

Neem oil kills pests and insects by 1) suffocating them upon contact and 2) by disrupting their bodily function when they ingest the treated plant. Neem oil suppresses their appetite, reduces egg formation, destroys their protective covering, and blocks their airways, so they end up dying.

Another function of neem oil is suffocating insects and pests upon contact. Its oil content covers their bodies and blocks airways to kill them. It also destroys the protective waxy coating of some insects, such as scales.

Insects and pests that neem oil can kill include mealybugs, scales, aphids, mites, locusts, and whiteflies. It can also destroy powdery mildew and anthracnose with direct contact. Neem oil prevents plant nematodes and root mealies larvae from hatching.

3 Methods Of Neem Oil Application: Step by Step Guide

Neem oil solution can be applied to the cactus either for preventative or treatment by using three methods: 1) direct spraying, 2) soil drenching, and 3) deep soaking. Always test a small portion of the cacti before using the solution to the whole plant to check if it can cause damage.

The mixture should only contain 0.5 to 1% of crude neem oil to prevent the burning effect on the plant caused by too much azadirachtin. However, if you use a clarified neem oil (lesser azadirachtin content), you can mix up to a 2% solution (6 tbsp neem oil) to get the same effect.

Here, I will provide you with a simple step-by-step guide of neem oil application to cacti plants.

1. Direct Spraying

Application through direct spraying is made by first preparing a neem oil solution, spritzer, and the plants. Spraying with neem oil is a preventive way to keep pests off and an effective method of treating infested cacti.

How To Do It?

1. Prepare the solution. To get started, prepare 1% neem oil solution using 1 gallon of water mixed with 5 drops of liquid soap and 3 tablespoons of pure neem extract. The soap helps emulsify the neem oil to blend with the water.
2. Mix well. Shake the solution vigorously to make the solution homogenous.
3. Pour the solution into the bottle. Carefully transfer an amount of neem oil solution to your spritzer and shake it well once more for even distribution.
4. Begin spraying. Drizzle your cacti with the solution, making sure to reach the undersides and nooks on the stem and spines to contact pests and insects. Cover all surfaces of the plant with neem oil for full effect.
5. Shake before spraying again. Remember to shake the bottle first before spraying because neem extract is an oil that doesn’t emulsify readily with water.
6. Leave to dry. When everything has been sprayed on, leave the plant in a shaded spot to absorb the solution before it evaporates.

A ready-to-use neem oil spray solution like the one below is an alternative if you’re not into mixing substances. You can spray it directly to the plant without adding any emulsifiers.

2. Soil Drenching

The drenching application uses a 1% neem oil solution from a raw extract mixed properly with an emulsifying soap in a gallon of water. The mixture is then poured directly into the soil to saturate the roots and absorb the neem oil.

This method makes the neem oil a systemic pesticide as cacti roots take the azadirachtin into its system. Any pests or insects that will bite the plant can get the toxic substance and kill them. Plant nematodes and fungus gnats inhabiting below the roots are also eliminated.

How To Do It

1. Prepare the neem solution. Take a gallon of water, add 5 drops of liquid soap, and mix to dissolve. Then measure 3 tablespoons of crude neem oil into the solution and stir briskly to blend them evenly.
2. Transfer the solution to the watering can. Pour the neem solution into the watering pot and agitate the container for further mixing.
3. Pour the solution directly into the soil. Gently water the potting soil using the neem mixture until the liquid flows down the drain holes.
4. Saturate the soil thoroughly. Ensure that the entire potting medium is soaked with the neem solution for better results.
5. Allow the roots to seep the solution. Place the plant in a cool bright place (under the tree, balcony) so that the neem oil mixture will not dissipate quickly and the roots will not burn due to the heat.

3. Deep Soaking

Another method is soaking the entire cacti in a 1% neem oil solution. The plant is plunged in the mixture for 1-5 minutes to allow chemicals to penetrate or contact every single pest present in the cacti.

This application is effective if your cacti are infested down to the roots from the stem. Soaking the potted cacti allows the solution to get into the entire surface of the plant.

How To Do It

1. Make a 1% neem solution. In a deep tub container, pour in a gallon of water, add 5 drops of liquid soap, and scoop 3 tablespoons of raw neem oil extract. Agitate vigorously to mix the components evenly.
2. Plunge the potted cacti into the solution. With long gloves on, submerge the whole plant entirely inside the tub with the neem mixture. Allow it to soak deeply for 1-5 minutes.
3. Take the plant out of the solution. The soaking time should not exceed 5 minutes to prevent overexposure to the solution. You will notice insects and pests floating on the surface, which means they are intoxicated.
4. Let it drip. Allow the excess solution to drain.

Below is a good neem oil product that I have been using in the garden.

When To Use Neem Oil?

Neem oil is applied to cacti at sundown when the temperature cools down a little bit. At this time, the solution will not evaporate right away, and the cacti will have a longer exposure to absorb the chemicals. Applying in the dusk lessens the tendency to affect the activities of beneficial insects.

Both spraying and drenching methods can be applied simultaneously or separately, depending on your plant’s situation and the severity of the infestation. If you are using neem oil as a preventative, do the drenching every 3-4 weeks and spraying every two weeks.

However, if you are applying neem for treatment on mealybugs, scales, aphids, and mites, you will need to re-apply for a better result. I recommend re-application after 1-2 weeks until the infestation is completely eliminated.

When using neem oil solution, always test for phytotoxicity on a small portion of the cacti before application to ensure that you have prepared the right concentration that is safe for the plant.

When Not To Use Neem Oil?

There are times that neem oil should not be used in your cacti plants because as it can have adverse effects like stem or root damage, burning, and killing off beneficial insects. These crucial times are: 1) during extreme cold or hot temperatures, 2) seedling cacti,3) newly repotted plants, 4) in mid-day, and 5) near ponds and beehives.

Here are the instances when you should refrain from applying neem oil.

1. During Extreme Cold Or Hot Temperature

Neem extract is pure oil. It will freeze in intense cold and burn when the temperature gets too high. It is not ideal to use neem oil when the environment is under these temperatures to avoid frost damage or burns.

Whether you use a spray or soak method, you should not apply neem oil when the surroundings are unfavorable. It will only cause irreversible damage to your cacti, such as rotting roots and burnt stems.

2. On Cacti Seedling

Another instance to avoid neem oil application is when cacti are still young and tender. A seedling cactus has soft stems and fragile roots that cannot withstand chemical contact. Neem oil can burn the seedlings and may kill them.

I do not recommend treating cacti seedlings with neem oil as it can be too harsh for their sensitive stem and roots. Wait until they develop thick epidermis, rigid spines, and strong roots. It is then they can tolerate chemical exposure.

3. Newly Repotted Cacti

Repotting can cause stress to the plant, and it is not ideal to expose them to chemicals such as neem oil. Roots inevitably break during repotting, and watering wounded roots will cause rot. So refrain from applying neem solution until the plant has recovered from repotting.

After repotting, allow the roots to develop first before introducing pesticides. Stressed cacti cannot withstand chemical contact, and they’ll end up burning and dying.

4. During Mid-day

Another situation when to avoid neem oil use is during hot summer daytime. The scorching sun can heat up the oil leading to plant burns. Also, beneficial insects are active during this time, and they can be in contact with the azadirachtin.

You should not apply neem oil when the sun is high, especially when your cacti are out in the open direct sunlight exposure. It will cause severe burning on the stem and cause brittle roots. Applying neem oil during the day will affect the activities of the beneficial insects due to its fume.

5. Near Ponds and Beehives

One more occasion when neem oil is not ideal for use is when your cacti are near the ponds or beehives. Neem oil is slightly toxic to fishes and bees.

When spraying or pouring, neem oil solution can get into the pond or beehives. Although it cannot kill them, fishes and bees are sensitive to neem oil’s odor and oil content.

Other Benefits Of Neem Oil

Neem oil has other benefits other than being an excellent pesticide and insecticide. Here is the list of neem oil’s uses.

• It can help treat fungal and bacterial infections on plant stems and roots.
• Several products such as toothpaste, shampoo, and cosmetics contain a small concentration of clarified neem oil.

Can I Use Neem Oil On Other Plants?

Neem oil can be used on other plants to repel and kill pests and insects. It is more effective on plants with smooth large leaves such as vegetables and herbs because neem can easily seep through the surfaces.

However, plants with fuzzy tender leaves may be sensitive to neem oil. So, it is vital to use the recommended concentration and check for phytotoxicity before proceeding with the application to avoid plant damage.

Summary On How And When To Use Neem Oil

• Neem oil is an extract from the seeds of a neem tree. It is a popular agricultural product because its active component, azadirachtin, has natural pesticidal and insecticidal properties.
• Neem oil can be applied to cacti using 3 different methods: direct spraying, soil drenching, and deep soaking.
• It is ideal to use neem oil during sundown so the cacti will not burn after application, and it can have more time to absorb the neem solution.
• Refrain from using neem oil under the following situations: during extreme cold or hot climate, when cacti are still seedlings, newly repotted cacti, burning mid-day, and when plants are near the pond or beehive.

Sources

• “What’s In A Neem” National Academic Press
• “Horticultural Oils – What a Gardener Needs to Know,” University Of Nevada Reno
• “Bees and Neem OIl Pesticide Sprays… OK,” University of California
• “Neem Oil General Fact,” Oregon State University

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