10 great ways to keep pests off your cannabis plants

Growing cannabis plants is fun and rewarding, no doubt about it, but you’re bound to encounter one or two problems along the way. One of those problems is pests.

Left unchecked, a pest infestation can ruin your entire cannabis crop. At the very least it can compromise yield, spoil the flavors and make a mess of your grow tent. But how can you keep pests away from your cannabis without resorting to harmful, chemical pesticides? Are there more natural, organic ways you can keep pests off of your marijuana plants?

In this article, we detail ten safe, tried-and-tested ways of keeping your garden pest-free.

If your cannabis plant does have an infestation of pests, you might be tempted to go for a quick-fix pesticide. Houston Cannabis Club does NOT recommend that you do so. Chemical pesticides can be toxic to both humans and the environment, and they’re not really what cannabis is all about.

No matter how bad the infestation, you should always ask yourself the following questions.

1. Can I sterilize the soil to get rid of cannabis pests?

The modern grower should really have more of a conservational mindset than the generations that have come before. We have more access to information than at any other time in history, and our interconnectedness means, in theory, that the whole world is a resource.

Reusing soil after a grow is a great example. You need to make sure you properly condition and prepare the soil before reusing it. 

If you use it without treating it, you risk exposing the new plants not only to diseases but also to nasty eggs and larvae. Left unnoticed, these could hatch and grow into pests, eventually wreaking havoc on the plants. Before reusing soil, you need to sterilize it to eliminate any harmful pathogens, pests and molds. Here’s how:

For small amounts, you can bake it in the oven. Cook it for 30 to 45 minutes, at 180°F (82°C). For larger amounts, simply add about2.5 tbsp of 3% hydrogen peroxide per gallon of soil.

If you think your new soil could be contaminated (maybe it’s poor-quality soil bought from an untrustworthy seller) you might want to sterilize it before you start. To be safe, stick only to reputable brands.

If you plan to sterilize the soil during a grow, be sure bring amendment and nutes back to healthy levels after treatment.

2. Will regularly sanitizing my cannabis grow room get rid of pests?

It’s a great preventative measure, but usually not enough on its own to fully rid a room of pests. Not only should you be cleaning more often than you think you should be, you need to keep your door or zip closed at all times. Open it only for access. This limits the entry window for bugs attracted to your plants.

You should also pick an outfit to wear when tending your cannabis crop. Keep it clean and hung up in a closet near the tent, and change out of your everyday clothes each time you visit your plants. This will prevent hitchhiking bugs from gaining access (and it’s great for preventing fungal spores, too).

When you do clean and disinfect your grow room, use rubbing alcohol or 10% household bleach solution to sanitize the area, focusing on surfaces, tools and door and window handles. 

3. Can I use fly strips to get rid of cannabis pests?

A fly strip – also known as flypaper, fly ribbon and flycatcher – is a pest control measure made of sweet-smelling, sticky paper. It’s hung around the cannabis garden, capturing and trapping any insects that fly into it. Placed in strategic spots – such as entrances, window panes and trash cans – and it will definitely reduce most infestations. Though it’s not usually enough to solve the problem on its own.

Tip: If using fly strips outdoors, replace them after a few days – airborne dust and particles soon render them ineffective.

Fly strips are best deployed to measure the rate of infestation. If you’ve just treated your plants for fungus gnats, for example, you should start seeing fewer gnats being trapped on the paper – so you will know your treatment has worked.

4. Will a protective barrier keep my cannabis free from pests?

Flycatchers are for flying insects. What about the creepy-crawlies? One solution is to create a sort of force-field on the ground using diatomaceous earth, a natural material made of microscopic bits of fossilized algae. It dehydrates ground-dwelling insects and is great at reducing their numbers. To apply, simply sprinkle it around the plants to form a protective ring.

5. Will companion planting keep pests off my cannabis grow?

Companion planting is how we describe purposely growing different plants close to the cannabis. It can lead to higher yields and superior soil quality, while repelling pests or attracting beneficial bugs.

Some plants have natural pest-repellent properties, secreting chemicals that can confuse or fend off pests. Others can attract friendly bugs that feed on common pests, helping prevent and mitigate the infestation. These are our fragrant picks of the bunch.

Basil. Pleasant and sweet-smelling, the fragrance of basil can repel bugs like aphids, beetles, mosquitoes, thrips and whitefly. Be sure to regularly prune your basil plants to encourage the growth of healthy, aromatic foliage.

Chili Peppers. As a companion plant, chili peppers can attract pollinators and natural predators. They give off toxic chemicals that can repel unwanted insects and even larger pests like mice, rabbits and deer.

Garlic. The high level of sulfur in garlic gives it a pungent smell and insecticidal and antifungal properties. Garlic is a fine repellant of ants, aphids, codling moths, fungus gnats, Japanese beetles and spider mites.

Marigold. Brightly-colored and beautiful, marigold is also a reliable pest control companion plant. It can ward off harmful insects such as beetles, nematodes and whiteflies, while attracting friendly bugs and pollinators.

Peppermint. The characteristic menthol scent of peppermint can drive away ants, aphids, beetles and fleas. It can also attract the ladybugs and predatory wasps that prey on crop-damaging insects. Just like other members of the mint family, peppermint can be invasive, with the underground rhizomes growing and spreading fast. 

Position your peppermint strategically. It should be far enough to leave resources for the cannabis, but close enough to do its job.

Sunflower. This iconic daisy-like flower is a magnet to bees and other pollinators. Additionally, the bright-colored petals also attract wasps, assassin bugs and other friendly insects that attack smaller pests.

Yarrow. The fragrant, tiny white flowers of yarrow attract beneficial invertebrates like aphid lions, hoverflies, ladybugs and wasps which kill spider mites and a range of other pests. Since it’s a weedy, invasive plant, keep it a good distance from your marijuana.

6. Will natural predators get rid of cannabis pests?

Natural predators are a great way to get rid of pests. You can buy them at garden centers, pet stores or online, but they can take a while to arrive.

Ladybugs can kill as up to 60 aphids a day, while doing a great job of eliminating mealybugs, mites and other soft-bellied critters. The praying mantis, which feeds on aphids, beetles, caterpillars, crickets and grasshoppers, is another great predator to have around – and it looks very, very cool. Parasitic wasps can also lower caterpillar populations, helping to keep your leaves uneaten and intact.

7. Can I use all-natural foliar sprays to get rid of cannabis pests?

Foliar spraying is one of the most common ways of applying insecticides, pesticides and fungicides. It’s quick and very effective.

It’s just a matter of spritzing the product on cannabis plants, ensuring they’re well-coated from the soil base to the leaf undersides. Spraying is best done early in the morning or evening – but never in direct sunlight, this can cause the active ingredients to degrade faster. Also, limit it to the vegetative phase as it may interfere with trichome production and/or flavor when used on flowering plants.

Foliar sprays can be bought pre-made and ready-to-use – just make sure they don’t contain toxic substances. You can also make your own using all-natural ingredients. These are some of the top homemade sprays to get rid of cannabis pests.

Oil-Based foliar spray

Using a mixture of mild soap and vegetable oil, an oil-based foliar is good against aphids, mites and thrips. Simply combine one tablespoon of mild liquid soap with one cup of your preferred oil. Canola oil, soybean oil, cottonseed oil and olive oil (we would keep the extra virgin for salads) are common choices. Mix thoroughly and use two teaspoons of the blend for every quart of water.

Soap-Based foliar spray

Similar to an oil-based spray, but without the oil! It can effectively get rid of beetles, mites and whiteflies. To prepare, dilute 1.5 teaspoons of mild soap to every quart of water.

Garlic-Based foliar spray

This blend is powered by the natural insecticidal properties of garlic, making it ideal for slowing down and controlling an insect attack. To make, puree two garlic bulbs and a bit of water in a blender until it has a creamy, paste consistency. Let it sit overnight before straining out the garlic bits. Add half a cup of vegetable oil, a teaspoon of mild soap and just enough water so that the solution makes a quart. To use, dilute a cup of the insect repellent for every quart of water.

Chili-Based foliar spray

Packed with insecticidal properties, a homemade chili spray can repel most insects and pests. Be sure to wear protective equipment such as goggles, gloves and a face mask – chili sprays can irritate the skin, eyes, nose and lips. You can use either fresh peppers or chili powder. 

With fresh peppers, puree half a cup of cayenne or habanero peppers in a cup of water. Add a quart of water to the paste, then bring it to the boil. Once the infusion has cooled down, strain out the peppers and add a few drops of mild soap to the solution. If using powder, combine one tablespoon of chili powder with a few drops of liquid soap in a quart of water.

Neem oil foliar spray

This odorous extract, which is sourced from the seed kernels of the Neem tree, is a potent remedy against pests, insects and fungal infections. It can kill some soft-bodied critters on contact, and is particularly effective against chewing insects like aphids and caterpillars. To prepare, combine two teaspoons of neem oil with a teaspoon of liquid soap. Dilute the solution in a quart of water.

8. Will predator urine get rid of my cannabis pests?

If you’re growing cannabis plants outdoors, small invertebrates are not the only thing you should worry about. Rodents and household pets like dogs and cats are also something to watch out for, as they like to burrow and trample on the crops. Even wild animals like rabbits, raccoons, squirrels, moles, deer and foxes can be a pain for growers.

You can train pets to stay out of the garden but undomesticated animals need a different solution – the urine of their enemies!

By spraying the urine of large animals – such as bears, pumas and wolves – any mammals who smell it will immediately back off. They will not want to invade the territory of dangerous predators. Urine products can be bought online and from outdoor or home improvement shops. It’s far easier to buy it than to obtain it from the animals themselves!!! 

Note: this is a modern world so this message is necessary – Homegrown Cannabis Co. is in no way encouraging our customers to wrestle bears, pumas, wolves, badgers, mammoths, avengers, tigers or any other creature for its urine. Just get it from a shop, please.

9. Can I build a fence to keep pests off my cannabis grow?

If the urine of large predators is not enough, you could consider erecting a fence around your crop – it should work for rebellious pets, too.

10. Can I install netting to keep pests off my cannabis grow?

Netting is pretty good at keeping birds off your crop, but you only really need it to stop the birds eating your seeds. This means it’s useful for the first few weeks after germination only, unless you’re pollinating your crop to produce new seeds. You can return the netting once the seeds arrive, leaving it up until harvest.

A pest-free cannabis garden needs an active gardener

Pest infestations have plagued gardeners for centuries – cannabis growers included. Seeing insects chewing on your plants isn’t just a frustrating distraction, they can cause a huge amount of damage to your cannabis plants – undermining their health, happiness and yield.

Fortunately, there are many ways to rid the growing area of pests – without resorting to harsh chemical pesticides. You need to be vigilant. Observe your plants, look out for bugs, make sure you keep everything clean, that you change clothes and basically do all the things an active, conscientious gardener should do. Prevent the infestation and treat it as soon as you spot it.