Neem Oil vs. Horticultural Oil: Which Natural Insecticide Should You Use?

Written by Mitchelle Morgan
Updated: June 15, 2023
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As an agriculture and gardening enthusiast, you know how pests can be destructive. You also probably know that, sometimes, pest control can also lead to crop destruction.

Many gardeners want to steer clear of artificial pesticides and try a natural alternative. Afterall, natural solutions have minimal human and environmental health concerns.

Neem oil and horticultural oils are popular alternatives. These two are friendly to the environment and effective. Each has its benefits, characteristics, usage instructions, and ingredients. We will explore their properties, pest targets, and their effectiveness. You will also learn how to use them well to avoid plant damage and gain the greatest benefits. Here is a detailed review of neem oil vs. horticultural oil.

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Properties of Neem and Horticultural Oils

In a way, neem oils and horticultural oils are the same. Horticultural oils are all-natural oils made from minerals, plants, and animals. At the same time, neem is also horticultural oil since it comes from a neem tree.

Neem oil is quite effective in ridding succulents of pests.

Neem oil is quite effective in ridding succulents of pests.

©iStock.com/Ninetechno

However, neem oil is very different from other agricultural oils. While horticultural oils prevent plant pests and disease invasion, neem oils repel and inhibit pests’ growth. Hence, these oils use different methods to achieve the same goal.

Neem oils control insects at all development stages: eggs, larvae, and adults. This oil has 140 active compounds, with azadirachtin as the active chemical. This explains its effectiveness in insect control.

Neem Oil Insecticide Properties in Agriculture

  • It has over 100 compounds: Azadirachtin is one of neem’s compounds. Although this substance is present in the whole tree, it is mostly in the seeds and fruits.
  • Affects pests differently: Generally, neem oil is a broad-spectrum repellent. It works on several pests like spider mites, aphids, and whiteflies. It regulates the pest’s growth, causes deformities in their offspring, and poisons the insects.
  • Causes anti-feeding effects: The oils make the plants unpalatable to insects, while also reducing the insects’ appetite. Additionally, if the insects feed on the plants, the oil hinders them from reproducing.
  • It has a systemic effect: Applying the oil to the plant base allows the plant to absorb the extracts via their roots. Also, when you spray the leaves, the oil absorbs into the plant’s system. So, you can use neem oil to control pests that are hard to control with normal sprays.
  • Works against 400 plus pests: Research shows neem extracts affect about 400 pests. Yet, the oil does not affect natural enemies. These pests include arthropods, spiders, wasps, and ladybugs. This is possible due to their feeding characteristics and low contact with products. The strength of your formula, timing, and application methods determine its possible effects.
  • Acts as insect repellant: This oil has a strong smell that repels insects. Hence, many gardeners use it to keep insects away from their plants.

Horticultural Oils Properties

Horticultural oils help to manage insect infestation on plants. These oils contain:

  • Paraffinic or mineral oils: These oils contain petroleum products and distillate.
  • Plant-based oils: Horticultural oils can contain neem, rosemary, soybean, and cottonseed, among others. Please note that the oils that contain neem will have an indicator to show their presence.
  • Fish oils: You can use this oil with plant oil, which is mostly inert.

The properties of this oil include the following:

  • Control insects through direct contact: This oil regulates mites and other soft-body insects when they come in direct contact with the spray.

Hence, the oil works through repelling or smothering. Also, some of these oils have mild fungicides to act upon rust, powdery mildew, and sooty mold diseases.

  • Suffocation action: These oils suffocate insects together with their eggs. They block the insects’ airways so that they cannot breathe.
  • Broad spectrum action: Oils affect insects in multiple ways. Note that the oils have less residual duration, meaning the oil’s active ingredient remains active for a short duration. This reduces the effects on beneficial organisms and insects.
  • Available in ready-to-use and undiluted formulations. You can buy ready-to-use oils or oil concentrates to dilute, depending on your preference. It’s important to read the labels before use.
  • Low toxicity: They are safe for pets, humans, and beneficial insects like pollinators.

Lastly, you must check the oil’s effects on different types of plants because some plants are not oil tolerant.

Also, it would be best not to substitute non-gardening or cooking oils on plants. This is because these oils may contain impurities and risk plant health.

Target Pests for Neem Oil and Horticultural Oil

Both neem and horticultural oils work best on specific pests. These include:

Neem Oil Target Pests

You can use neem oils for both outdoor and indoor plants to regulate pests.

Neem extract can help to control:

  • Aphids – These insects have soft and small bodies. They cause leaf distortion and growth stagnation when they feed on plant sap.
  • Whiteflies – These are small flying insects that take up leaf sap and leave a sticky substance. Then the substance enhances sooty mold and also attracts ants.
  • Spider mites – Mites may cause leaf drooping and yellowing as they suck plant sap.
  • Mealybugs – These insects have small, soft bodies. They may distort leaves and cause growth stagnation.
  • Thrips – These insects are small, with slim bodies. They rely on plant tissue, causing leaf distortion and curling.
  • Small-scale insects – These tiny insects attach to plant leaves and stems while sucking sap. With time, the leaves wilt, turn yellow, and drop.
  • Caterpillars – Neem oil treats caterpillars like armyworms and cabbage loopers.

Besides controlling these pests, neem oil can also control fungal diseases. It can help with black spot, scab, blight, anthracnose, and powdery mildew. Note that you cannot use neem oil to control all pests. So, identify the pests and look for the right product.

Target Pests for Horticultural Oils

Makes Armyworms So Bad

Horticultural oils can help control armyworms.

©kale kkm/Shutterstock.com

You can use horticultural oils to control:

  • Caterpillars (tent caterpillars, leaf rollers, armyworms, webworms, hornworms, and codling moths.)
  • Insects with soft bodies (psyllids, aphids, adelgids, and leaf beetle larvae)
  • Mites
  • Scale insects (kermes scale, striped pine, pine needle, and cottony maple)
  • Spider mites
  • Leafhoppers
  • Whiteflies

On top of the above pests, horticultural oils also help to control some fungal diseases. You can use it for sooty mold, rust, and powdery mildew.

Neem Oil vs. Horticultural Oil: Effectiveness Comparison

Neem and horticultural oils are easy to use and effective. You only need to spray them on your plants in need. But their effectiveness depends on the type of formula and different application methods. Here are the top factors to consider:

Suffocating Action

Neem oil uses several modes to control pests. It disrupts the growth and development of pests, inhibits feeding, and repels them. In contrast, horticultural oils suffocate insects and disrupt their breathing.

This means that neem oil is mostly effective against pests that don’t succumb to suffocation.

Residual Activity

Neem oil does not remain on the plant for long. So, you will need to apply neem oil in intervals for it to be effective. In contrast, horticultural oils can remain on the plant for some time.

Systemic Action

Plants can absorb neem oil through their leaves and roots and supply it to the rest of the parts for systemic protection. In comparison, horticultural oils affect pests through contact. Pests must come into contact with the oil for it to work.

Both Are Broad Spectrum

You can use both oils for various pests.

Eco-Friendliness

These oils are environmentally friendly. However, horticultural oils may affect aquatic invertebrates and fish. In contrast, neem oil is not harmful to aquatic life.

From the above explanation, each oil is effective depending on the pest and how you apply it. Use neem oil to deal with soft-body pests, since suffocation might not work. And use horticultural oil to deal with pests that will succumb to suffocation.

Neem Oil vs. Horticultural Oil: Safe Usage Guidelines

Safety Guidelines for Horticultural Oils

When using horticultural oils as insecticide, here are some safety usage guidelines:

Read the Label

Before you open the package, read all the labels and directions. You will learn timing, application, and precautions.

Cover the Plant Thoroughly

Apply horticultural oils on the leaf’s upper and lower sides or back. If you use it as a fungicide, you must completely cover the plant leaves on the upper side.

Temperature Regulation

Apply horticultural oils at the right temperatures to avoid plant damage. Please note that these oils may damage plant tissue, especially leaves. This may happen if you apply the oils with high heat or low evaporation.

It is advisable to apply when the temperatures are below 85 degrees Fahrenheit, such as in the morning or in the evening during summer.

Always apply horticultural oils with temperatures between 50-60 degrees Fahrenheit and above. Then repeat the application for several days. This temperature helps keep the oils at their optimum viscosity.

Test the Plants First

Always test the plant oil sensitivity by spraying on a small part. This is important when you need clarification on the plant oil tolerance level. Then wait for about two days for the reaction. Also, do not use these oils on plants with gray or blue foliage because the oils may interfere with their coloring wax.

Repeat the Application

Re-application helps deal with pests that didn’t die in the first application. But check the instructions to know how long to wait between your spraying sessions.

Consider Re-Entry Duration

This refers to the time you must wait before going to the treated areas or the wait time before eating vegetables. You must read the oil’s label for these instructions and wait until the time lapses.

Spray Away from Water Bodies

Horticultural oils may lead to aquatic life intoxication. Refrain from spraying near rivers, ponds, lakes, or other water bodies. If you must do so, consider using buffers to avoid overflows.

In addition:

  • Always ensure the plants are well hydrated before spraying. In drought, you must water the plants for hours or days before spraying.
  • Avoid spraying on open blossoms to avoid harming pollinators.
  • Use the oils alone. Avoid combining them with other insecticides.

Safety Guidelines for Neem Oils

You can use neem oil to protect crops from pests and insects without harsh insecticides. You must use it well to avoid crop damage and also achieve good results. For efficiency, use the tips below when using neem oil on your plants:

Read the Product Label

Read the label well to get instructions on using the product to achieve results. Also, this will help you with proper timing, safety precautions, and quantities.

Use it in a Safe Place

If you use neem oil for indoor plants, move them away from kids and pets.

Test On a Small Part

If you are unsure whether your plants are oil tolerant, try using some oil on a small part. This helps to avoid damaging the whole plant or large portions of the plant.

Apply the oil for about 24 hours to see the possible effects on the plant. Then proceed if there is no discoloration or burns.

Apply on All Parts

To get good results, apply your neem oil on the plant’s leaves, top and bottom. Pay special attention to the bottom side since many pests hide there.

Don’t Overdo it

Apply a light coat on the leaves and repeat after seven to 10 days, depending on the manufacturers’ guide.

Repeat Application

Neem oil may take some time to take effect. So, repeating the application process is good until you get the results. If you want to use neem oil for bacteria and fungi, use it in pure form. This will help to eradicate the diseases in your fruits and vegetables.

Spray Before/After Blooming Season

Use neem insecticides when the plants are out of flowering season. You can spray them in two-week intervals until their buds open. Stop, then proceed when the flowers drop. This helps to reduce the oil’s effects on pollinators and other useful animals.

Soak the Soil with Pesticides

Plants can absorb neem oil through their leaves. Prepare an insecticide solution and pour two to three cups around the tree base. Repeat the process every two to three weeks until the pests die, and the plant is disease free.

Finally, avoid applying neem insecticides on poor-quality plants. Instead, revive the plant and then proceed with the insecticides. Meanwhile, you may use root soak to curb the insecticides as the tree recovers.

Neem Oil vs. Horticultural Oil: Key Takeaways

  • Both neem oil and horticultural oils are natural and effective insecticides. Consider the differences to determine the best choice for your plants.
  • You can use neem oil to control various pests and diseases. This oil is a fungicide, miticide, and insecticide all in one. The oil comes from neem tree seeds, and it’s safe around people and pets and for butterflies and bees.
  • While horticultural oil has petroleum content, it helps control many pests. This includes scales, mites, and aphids. You can also use it for some fungal diseases. But you must be careful as it harms beneficial animals like pollinators.
  • Your choice of neem oil vs. horticultural oil depends on the types of pests, as well as the effects of these oils on pets and beneficial animals.

The photo featured at the top of this post is © iStock.com/Zbynek Pospisil


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About the Author

Mitchelle is a content writer who loves nature. She loves writing about animals and plants. In her free time, she enjoys hiking and going for nature walks.

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