Photo by Michelangelo Buonarroti

Guides | 03.29.2024

Best Homemade Bug Spray For Weed Plants

Shield your precious weed plants from pests with this homemade bug spray recipe, crafted from natural ingredients and designed to protect your crop while maintaining its integrity.

Growing cannabis is rewarding but also comes with challenges like dealing with pests and insects. While store-bought pesticides are an option, many prefer natural and homemade remedies to keep their plants healthy. 

This article will provide detailed instructions on how to make several highly effective homemade bug sprays using common kitchen and garden ingredients. These organic sprays are safe alternatives to harsh chemicals and can help eliminate various pests that plague cannabis gardens. 

Best Homemade Bug Sprays For Weed Plants

Oil-Based Insecticide for Weed Plants

Photography by Georgia Love for Herb

Oil-Based Insecticide

One of the simplest and most versatile homemade bug sprays combines vegetable oil with soap. This oil-based insecticide suffocates pests like aphids, thrips, and mites by coating their bodies and pores. 


  • 1 cup vegetable oil (canola, soybean, or cottonseed oil works well) 
  • 1 tablespoon castile soap 
  • 1-quart water 


Step 1: Mix the oil and castile soap thoroughly in a small container. This helps the oil and soap emulsify into a sprayable mixture. For every 2 tablespoons of the oil-soap mixture, dilute it into 1 quart of water. Place the diluted mixture into a spray bottle to apply to plants. 

Step 2: The soap acts as an emulsifying agent, allowing the oil to mix evenly with water so it sprays on evenly. It also adds its mild pesticidal properties. The oil smothers pests by coating their exoskeletons and clogging their breathing holes and pores. This leads to dehydration and death within a day or two after treatment. 

Step 3: This spray works against a wide variety of common cannabis pests. It’s effective, inexpensive, and comparatively gentle on plants compared to harsh chemical treatments. For best results, be sure to thoroughly coat all leaf surfaces during application. 

Soap-Based Insecticide

A variation on the oil-based spray substitutes plain soap for the oil component. This soap-based version is just as effective for certain pests while being safer and easier to prepare. 


  • 1 1⁄2 tablespoons mild soap, such as castile soap 
  • 1 quart water


Step 1: Start mixing the liquid soap thoroughly into the water. Place the mixture into a spray bottle. Like the oil spray, thoroughly coat all plant surfaces, targeting the undersides of leaves where pests tend to hide. 

Step 2: This spray is ideal for killing whiteflies, spider mites, and beetles that may infest outdoor cannabis gardens. Its soap works in much the same way as the oil version to dehydrate and suffocate pests. 

Step 3: For best results, apply the soap spray early in the morning or at dusk when temperatures are cooler and pests are most active. Reapply every 3-5 days as needed until pests are fully eliminated. 

Garlic-Based Insecticide

Garlic is one of the home garden’s most powerful natural insect repellents. Its strong odor deters many pests from landing on or feeding on treated plants. Garlic also has antioxidant and antibacterial properties. 


  • 2 whole bulbs garlic (not cloves) 
  • 1⁄2 cup vegetable oil 
  • 1 teaspoon mild liquid soap 
  • 2 quarts water 


Step 1: Finely mince or puree the garlic bulbs in a blender with a small amount of water. Let the mixture sit overnight to allow the juices to extract before straining out the solids. 

Step 2: In a jar, mix the strained garlic juice with 1⁄2 cup oil and 1 teaspoon soap. Let this emulsion sit for a few more hours to combine. 

Step 3: Pour 1 cup of the garlic-oil-soap mixture into 1 quart of water and shake vigorously to mix. Pour the remaining garlic concentrate into the second quart of water and shake again. 

Step 4: Transfer the diluted mixtures to separate spray bottles for application. Coat plant surfaces 2-3 times per week, targeting the undersides of leaves. The potent garlic odor will deter many common bugs from infesting treated plants. 

Chili-Based Insecticide For Weed Plants

Like garlic, fresh chilies and chili powder have insect-repelling properties. Their spicy scents confuse pests, masking plant cues. Chili also contains capsaicin – the compound that gives heat. This deters many species from feeding or reproducing on treated surfaces. 

Fresh Chili Version: 

  • 1⁄2 cup fresh chilies, finely chopped 
  • Liquid soap 
  • 1 quart water

Chili Powder Version: 

  • 1 tablespoon chili powder 
  • Liquid soap 
  • 1 quart water 


Step 1: For fresh chilies, puree the chopped peppers in a small amount of water and strain. Add the chili liquid to a quart of boiling water, remove from heat, and allow to steep and cool. 

Step 2: Or, simply mix 1 tablespoon chili powder directly into a quart of water. 

Step 3: Once cooled, add a few drops of liquid soap to either solution and transfer to a spray bottle. Coat plant leaves, targeting undersides. 

Step 4: Reapply every 3-5 days until pests are eliminated. The chili acts as a deterrent rather than a killer, staving off many common cannabis bugs through its spicy odor. 

Tomato Leaf Insecticide

Tomato leaves contain alkaloids closely related to those in nightshade family plants like potatoes. These alkaloids sicken and deter many insects that feed on cannabis, such as aphids. They make tomato leaves a potent bug-repellent additive. 


  • 2 fresh tomato leaves 
  • 1 quart water 


Step 1: Simply place the tomato leaves into the quart of water and allow it to steep overnight. In the morning, strain out the leaves, then transfer the infused water to a spray bottle. 

Step 2: Coat cannabis plant surfaces with the tomato “tea”, focusing on new growth. The alkaloids in the leaves will ward off many insect pests without harming your plants. Reapply every 3-5 days for ongoing bug protection. 

Garlic, Onion & Cayenne Insecticide

Combining garlic, onion and cayenne chili powder creates a super-charged bug spray. Used together, these ingredients provide multi-pronged pest deterrence through their individual compounds. 


  • 1 garlic bulb, minced 
  • 1 small onion, minced 
  • 1 teaspoon cayenne powder 
  • 1 tablespoon liquid soap
  • 1 quart water 


Step 1: Puree the minced garlic and onion with the cayenne powder in a small amount of water. Let the mixture sit for at least 1 hour to infuse. 

Step 2: Strain the pepper-garlic-onion concentrate, then add it along with 1 tablespoon of liquid soap to a quart of water. Transfer to a spray bottle and apply to plant surfaces as usual. 

Step 3: The potent blend of odors confuses pests while capsaicin from the cayenne gives an extra kick. Reapply every 3-5 days for multi-pronged protection against a wide spectrum of common cannabis crop bugs. 

Neem Oil Insecticide

Neem oil is one of the most effective natural pesticides for cannabis. Extracted from seeds of the neem tree, it is safe for plants and people when diluted and applied correctly. Neem oil kills insects by disrupting their molting process and reproductive development. It also repels many species from landing on leaves. 


  • 2 teaspoons neem oil 
  • 1 teaspoon liquid soap 
  • 1 quart water 


Combine the neem oil, soap, and water, then shake vigorously to produce an emulsion. Transfer to a spray bottle and apply to all surfaces of cannabis plants, paying close attention to the undersides of the leaves. 

Neem oil kills eggs and larvae of many bugs while repelling adults. It also helps control powdery mildew and other fungal diseases that plague gardens. Spray plants weekly until pests are eradicated, then every 10-14 days for maintenance. Take care not to over-apply to flowers or new growth. 

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