Pest Control for Outdoor Cannabis Grow: Simple Steps To Prevent And Eliminate Pests

When growing cannabis outdoors, there’s always some risk to your plants. They are exposed to the elements. 

Although cannabis is quite resilient to most such risks, one problem can wreak havoc in your garden — pests. 

Pests are a common nuisance for all kinds of gardens and farms, and cannabis is no exception. A few bugs aren’t a problem, but they can quickly grow in numbers and create a domino effect of problems on your plant. 

Pests can cause nutrition deficiencies, stunted photosynthesis, slowed growth, reduced yield, mold or fungal infections, diseases, and a lot more.

So, you must control pests in your outdoor cannabis garden. Here is a guide on doing the same. 

Why Do You Need Pest Control to Grow Cannabis?

For one simple reason — pests are a nuisance for cannabis plants and can potentially kill them. Pests are one of the most common problems growers face when growing cannabis outdoors and these pests can damage your plants in various ways, depending on what kind of pests they are.

Commonly, these are the kinds of pests you may face while growing cannabis outdoors:

• Sucking Pests

These are parasitic pests that suck the nutrients out of your plant, which hamper the plant’s growth and even reduce the overall yield during harvest.

• Chewing Pests

Chewing pests feed on your plant. They eat leaves, branches, and buds, and harm the plant in various ways from stunting its growth, making it more prone to infections, and reducing the yield.

• Infectious Pests

These pests don’t directly take anything from the plant, but they can carry harmful pathogens or spores that can infect your plant, which can create various problems for your plant such as mold and fungus, diseases, and a lot more.

Of course, there are other varieties of insects, but these are the most common ones, including spider mites, aphids, fungus gnats, slugs and snails, thrips, and caterpillars, along with many more. 

It's best to ask an experienced grower to know more about the common pests in your area. 

How to Control Pests in an Outdoor Cannabis Garden?

Fortunately, you are not alone. Farmers across the world have to deal with such pests, so they have come up with various tried-and-tested methods to control pests on their farms or in their gardens. Most of the techniques work well for cannabis growth, too. 

Here are some of the common ways to control pests for outdoor cannabis.

1. Grow Companion Plants

Companion planting is a method of growing specific plants around your cannabis plant that can help control the population of pests in the garden, and these plants can also improve your cannabis plant’s growth. 

Thanks to evolution, companion planting is quite effective. When plants grow next to each other, they develop a symbiotic relationship, which benefits the entire garden. By planting companion plants, you are recreating this symbiotic relationship in your garden. 

It’s like growing friends for your cannabis.

Fun fact: companion planting is a practice of permaculture, which aims to create an ecosystem of plants and animals that help each other out to reduce the grower’s reliance on nutrients!

• Companion Plants Deter Pests

How can companion plants help deter pests? In two ways. Companion plants for cannabis either distract the pests or trap them. Some companion plants have a strong odor, thanks to their oils, that repel pests from the garden, and others act as a decoy, keeping the pests occupied so they don’t reach your cannabis plants.

• Other Benefits of Companion Plants

Companion plants also serve various other benefits, such as the following:

• Some plants inhibit the spread of fungal spores, which keeps your cannabis safe from fungal diseases
• They improve soil health by fixing nitrogen and other nutrients, which further help your plant by providing nutrients easily 
• Since it’s a part of permaculture, it is 100% eco-friendly and natural 
• Some companion plants also improve the flavor profile of cannabis buds with their potent aromatic oils without tainting the buds
• Tall companion plants can help hide your cannabis plant (even its smell) from peeping eyes

Best Companion Plants for Cannabis

If you want to use companion planting to deter pests for cannabis, here are some of the plants you can grow:

• Lavender — diverts pests and attracts beneficial pollinators
• Sunflower — deters pests
• Cerastium — acts as a mulch to protect the soil
• Peppermint — deters pests and masks the cannabis smell
• Marigold — deters pests
• Alfalfa — deters pests and improves soil drainage 
• Red clover — acts as a nitrogen fixer
• White clover — repels pests, fixes nitrogen, controls weed growth (not cannabis), and acts as a mulch
• Dill — deters pests 
• Lemon balm — deters pests
• Comfry — fixes nutrients and prevents the spread of mold spores
• Thyme — protects cannabis from fungi 
• Sweet peas — act as mulch and prevent weed growth 
• Borage — fixes nutrients and vitamins in the soil
• Basil — masks cannabis odor, repels pests, and improves the buds’ flavor profile
• Coriander — repels pests
• Oregano — attracts beneficial insects
• Chamomile — prevents fungal spore spread, deters pests, and fixes potassium and calcium in the soil

2. Bring Beneficial Insects into Your Garden

Companions for your cannabis plant need not only be plants, they can be insects too. Because sometimes, you need poison to neutralize poison. This is where beneficial insects can help your cannabis grow.

Beneficial insects are predatory insects that specifically target harmful pests, they hunt around the clock and consume pests (along with their eggs and larvae) near your cannabis plant. They can both prevent and control pests in your garden. 

The benefits of beneficial insects go beyond pest control — they promote a rich ecosystem in your garden and are a natural alternative to chemical treatments. They can also help nurture other companion plants like mint, dill, lavender, etc.

• Introducing Beneficial Insects in Your Cannabis Garden to Prevent or Kill Pests

If you are growing cannabis outdoors, there is a chance many beneficial insects are already in your garden. But if they are not, worry not, introducing beneficial insects is quite easy. 

However, before moving ahead, you need to know exactly which pests have attacked your garden or are more common in your local region. This will help you invite the right beneficial insects that will prey on those pests. 

Once you know which pests you want to eliminate, you need to get the right species of beneficial insects. Here are some of the common species and the pests they prey on:

• Ladybugs — prey on aphids, moths, thrips, mites, and beetles
• Predator mites — prey on spider mites
• Praying mantis — prey on aphids, caterpillars, and flies
• Rove beetles — prey on fungus gnats
• Nematodes — prey on fungus gnats, ants, weevils, and slugs
• Green lacewings — prey on aphids, thrips, spider mites, whiteflies, and leafhoppers

But don’t be restricted to this list — there are many beneficial pests that you can use. 

Note that in different regions, some pests are more of a threat than others. Know more about your local environment and the common pests and choose beneficial insects that prey on them. 

To get your hands on these insects, you can visit your local horticulture or gardening store, and purchase these insects from there. You can also naturally invite these insects by growing specific companion plants in your gardens like oregano and lavender.

3. Use Homemade Neem Oil

Neem oil, one of the best natural pesticides for cannabis, is tried and tested by farmers for decades, making it an effective way to control pests for outdoor cannabis growth as it can both eliminate and prevent pests in your garden.

Neem oil works for cannabis plants in two primary ways:

1. Neem oil contains azadirachtin, which interferes with the pests’ hormone systems, making it harder for them to grow, lay eggs, and feed themselves
2. The same compound also disrupts the pests’ mating and sexual communication, which further reduces their reproduction abilities 

Additionally, experts also claim that neem oil coats the insects, reducing their ability to breathe. Although neem oil does not necessarily kill pests as other pesticides would, it forces the pests to move out of your garden.

What makes neem oil special is that it is completely organic and will not harm your plant in any way, as long as you don’t spray it on the buds, which can affect their flavor profile. In addition, make sure you don't use neem oil straight out of the bottle. You need to emulsify it with soap or other emulsifying agents to make it work or it will coat your plants with oil and some plants may even die!

Additionally, neem oil is effective against 200+ species of pests like aphids, spider mites, broad mites, fungus gnats, thrips, whiteflies, and mealy bugs, while being completely safe for beneficial insects like butterflies, praying mantis, bees, and earthworms. 

Many growers also use neem oil to tackle fungal or mold infections on their cannabis plants, including serious problems like root rot, as it can clear the spores way better than most other alternatives.

• Using Neem Oil on Cannabis

You can purchase neem oil from your local gardening store, but it is generally not recommended. Premixed neem oil may contain other additives or may not have adequate azadirachtin, making the mix less effective.

Instead, it is recommended that you make your cannabis neem oil spray at home using these steps:

1. Purchase 100% raw, cold-pressed neem oil — hard-pressed neem oil does not contain azadirachtin
2. Get an emulsifier so the oil can mix well with water, like potassium soap, organic insecticidal soap, or silica
3. Add 1 teaspoon of soap to 1 gallon of water and mix well
4. Add 4 teaspoons of neem oil to the mixture and shake well 

Remember to use the neem oil within eight hours after preparation. Also, some cannabis strains don’t react well to neem oil, so we recommend a patch test — spray one leaf and wait for a day. If the leaf does not show any side effects, your plant won’t react negatively to it.

Also, neem oil is pungent and has a strong aroma, so avoid spraying it on buds at all costs. It can alter the flavor profile drastically. Instead, only spray it on the leaves and branches lightly; don't soak it, and don't spray during the last three weeks of flowering. 

4. Use a Neem Oil Alternative for Cannabis Pest Control

In some cases, you may not want to use neem oil, especially if your plant is suffering from nutrient deficiency, watering stress, or the temperatures are too hot or cold. In that case, you can use one of the neem oil alternatives, such as the following:

• Spinosad

Spinosad is a terrific organic pesticide alternative to neem oil that is safe for your plants, children, and pets. It is made by fermenting a specific soil bacteria, and when ingested by the bugs, it interferes with their nervous system, killing them.

And using this pesticide is also quite easy. All you have to do is mix it with water and spray it on the bug-infested areas, like under the leaves, and you can be liberal with it as it is dilute compared to other solutions.

You can use this pesticide against grasshoppers, crickets, caterpillars, aphids, thrips, and spider mites. However, Spinosad is also harmful to bees for up to three hours after application, so only use it at night when the bees are inactive. 

• Horticultural Oils

On the other hand, you can also use horticultural oils — concentrated oil extracts from other plants that effectively repel pests. And these oils are completely natural, too. 

You can purchase horticultural oils from your local gardening store and use a mister to spray them on your plants. But they only last for around eight hours, so you will need to spray them consistently multiple times to eliminate all the pests. 

What sets horticultural oils apart from other pesticides is that they don’t create a film on your cannabis plant, so you don’t have to worry about harming your plant accidentally. 

5. Other Alternatives to Prevent or Eliminate Cannabis Pests

• Alcohol and Water

Another great pesticide to control pests in outdoor cannabis gardens is a mix of alcohol and water — easy, cheap, and effective against spider mites, mealybugs, and other common cannabis pests. 

All you have to do is mix 9 parts water with 1 part rubbing alcohol and spray it on your cannabis plant once a week. This mixture evaporates within minutes without creating a film on your plants, but it is still strong enough to kill the pests. 

• Use Diatomaceous Earth

Diatomaceous earth (DE) is made from fossilized remains of diatoms, small marine organisms. Diatoms were algae-like species that fossilized into this kind of powdery substance over 30 million years. 

This powder offers various benefits for cannabis, one of them being pest control. It is abrasive and physio-absorbent. It destroys the outer shell of the insects, making them dehydrate and die. At the same time, it is really sharp, so it can cut pests. 

Additionally, DE also conditions the soil by improving moisture and nutrient retention while allowing for better oxygenation. And the silica content in DE makes the nutrients more efficiently available to the plant. 

• Sterilize the Soil

Many pests reside in the soil and not all pesticides work as a soil drench. In that case, you can sterilize the soil by exposing it to high temperatures to kill off the pests. However, there is a downside to sterilizing the soil — it is time intensive, and for many growers, the process is not worth it as it also kills off the good bacteria and microorganisms.

But it may still benefit your plant. So, if you want to sterilize the soil, you can do that to eliminate the pests within. 

There are two ways to sterilize the soil — chemical and heat treatments. Chemical treatment is where you apply a specific chemical to the soil, which will quickly sterilize the soil. But this process is only beneficial for large farms, not for small cannabis gardens, and it has some potential hazards as it can affect the soil quality in the long run and some chemicals may be toxic and non-eco-friendly.

On the other hand, heat treatment is a lot better for cannabis gardens. You can apply heat to the soil either via steam or directly, which will eliminate harmful organisms, spores, and even weed seeds. 

Here are some ways you can sterilize the soil.

• Solarization Technique

With solarization, you can use the sun’s heat to sterilize the soil, and this technique is relatively easy for most gardens. Follow these steps to sterilize the soil with solarization:

1. Spread out your potting soil, and if you are using your garden bed, even it out. 
2. Water the soil to get it a little moist.
3. Cover the soil with a plastic sheet and secure the sheet with rocks along the edges. 

On the other hand, you can even use plastic bags. Add your potting soil to plastic bags and leave them out in the sun. Generally, it takes around a month during the hottest part of the year for the soil to be sufficiently sterilized. 

Also, use clear plastic of thin to medium thickness (1 to 2 mm) as it is better at trapping the heat compared to dark plastic, which can deflect the sun’s heat. 

• Boiling Water or Steam Technique

You can also use boiling water to sterilize the soil, but for this, you would require a steaming container. Follow these steps:

1. Set up the steaming container by adding two inches of water at the bottom and placing a rack of the sterilization container above it. 
2. Add four inches of soil to the container and cover it tightly with foil.
3. Place a lid on the steaming container but leave it slightly cracked to prevent the steam from building up within.
4. Let the water boil for 25 to 30 min. 
5. After 30 min, remove the sterilization container and let it sit until it reaches room temperature before removing the soil.
6. And keep the soil covered with foil until it is time to use it.

• Oven Technique

Another easy technique for sterilizing soil is using an oven — it is easy and you don’t need a steaming container, either. But it is only good for a small batch, so it will only work for a couple of plants’ potting soil. Follow these steps:

1. Add three inches of soil to an oven-proof container. 
2. Add some water to moisten the soil, but don’t make it too wet as it will slow down the heating process.
3. Cover the container with foil. 
4. Place it in a preheated oven at 200°F or 93°C.
5. Monitor the soil’s temperature and let it bake for half an hour.
6. Then, let the soil cool down after taking it out of the oven.

What are Some Tips to Control Pests in an Outdoor Cannabis Garden?

The above-mentioned tips work well to control pests for outdoor cannabis growth, but you can take this process to the next level by being smart about your garden. Here are some tips to help you control the pests:

1. Check the plants regularly for pests, especially under the leaves, where most pests like to hide. Also, look for signs of stress or bites. 
2. Always use a wide-spectrum organic pesticide on new clones when you bring them to your garden — many pests may hitch a ride on them, and a few eggs are enough to infest your garden. 
3. Ensure your garden is well-ventilated as bugs don’t like wind, which prevents them from mating or laying eggs around your garden. 
4. Whenever you are using cannabis pesticides, use them properly. 

Follow these tips:

• Do not overspray your plant with pesticides, no matter how organic or natural they are as they may hurt your plant by causing light burns
• Always know what pest you are dealing with and use an appropriate pesticide to deal with that pest
• Use cannabis forums to do research and get second opinions on pesticides you want to use 
• Avoid using any pesticides on the buds — they will affect the buds’ flavor profile 
• Always carry out a patch test on your plant while using a new pesticide to ensure your plant does not react negatively to it 

Summary: Pest Control for Outdoor Cannabis Grow: Simple Steps To Prevent And Eliminate Pests

Controlling pests is relatively easy, but you must never overlook this aspect of growing cannabis outdoors. Pests have the potential to not only stunt your plant’s growth and reduce the yield but also kill them. 

Use the techniques mentioned above, and don’t hesitate to use them together, so you can keep the number of pests down in your garden. To reiterate, for most growers, the best pest control techniques include growing companion plants, bringing beneficial insects, and using organic pesticides regularly.

But some growers may need to go further and use stronger pesticides, sterilize the soil, and even use nets to protect their cannabis plants.

So, you must understand what kind of pest risk your cannabis plant is at, and what pest species are common in your area. Also, discuss with local growers to narrow down the best pest control method for your cannabis plants and use them when needed.