Medically Reviewed by
Jason Crawford

Article Last Updated on January 18, 2023

Keeping your hemp garden healthy and thriving is every cannabis grower’s priority as it’s the only way to get bountiful harvests with precious cannabinoids. Growing cannabis is a rewarding activity, but very often this also means that you need to find solutions to problems that may arise during the growing season.

One example is dealing with pest infestations – a nuisance that can really damage your hemp plants. Outdoor growers are at a bigger risk of pest invasion, but even if you grow indoors, they can still find a way to sneak into your grow room.

Hemp plants (Cannabis Sativa L.) are nestled by the same pests that go after marijuana plants. There are many types of cannabis pests (fungus gnats, thrips, whiteflies, spider mites, caterpillars, inchworms, etc.), but today, our focus will be aphids, as they’re among the most common and most destructive ones. We’ll cover what they are and how to spot them, and of course, how to get rid of them.

What Are Aphids?

Aphids are small soft-bodied insects, whose size can be between 1-10 mm. They can be white, green, red, or black, and they’re pear-shaped. They have a pair of antennae on their head and a pair of tube-shaped structures called cornicles on their abdomen. There are thousands of aphid species, but the most commonly found on hemp plants are green aphids that are about 1 mm long.

Most aphids are nonsexual for most of the season and they deliver nymphs asexually or through parthenogenesis. However, other species will develop their sexes at the end of the season and will start to mate to produce eggs to lay over the winter.

Most adult aphids don’t have wings, but some species will develop wings at some point during their life cycle to enable them to migrate and disperse. 

Winged aphids most often hatch when the weather starts getting warmer – at the start of spring, and they produce female nymphs that would soon give birth to more young. This cycle will happen a few more times which makes them reproduce very fast in a short amount of time, which is why acting fast is important.

By the time summer ends and fall starts, male and female aphids that have developed sexes start to mate to lay eggs.

How They Can Damage Hemp Plants

These pests are sucking insects and they feed off of plant juices. They puncture the leaves, stems, and branches and suck sap. They suck large amounts of plant juice because they need the proteins present in the sap. When they have enough juice, they extract the proteins from it and excrete the excess sugars. This sugary substance is called “honeydew” and it’s similar to molasses. 

The honeydew they produce attracts ants, which protect aphids from predators in return. However, honeydew is not harmless as it creates the perfect conditions for the development of sooty mold and mildew.

When aphids suck precious plant juice from your hemp plants, they deprive them of essential nutrients for growth and survival. This can result in curling, wilting, or yellowing of the leaves, as well as stunt the growth of the plants. Aphids are also unwelcome because they can transmit viruses and bacteria when they feed on the plants.

How to Spot Aphids in Your Cannabis Plants

Aphids are most commonly found on the underside of leaves where they hide from sunlight, but they can also be seen on the leaves and stems. You can also recognize you have an aphid problem if you notice small white dots which appear on the sites where the aphids have sucked on the plant. Or, you may even spot small dark patches on the leaves, which should be the honeydew they leave behind.

While most aphid species are found on the plant foliage, root aphids live in the planting medium and feed on the plant roots. This makes inspection and detection much more difficult.

Can You Prevent Aphids From Damaging Your Cannabis Garden?

You can prevent aphids from ruining your hemp plant with regular inspection (once a week) and adjusting the conditions in your growing space. Most pests like stale air and warmer temperatures, so keeping your grow space properly ventilated and with temperatures between 68 and 77 degrees Fahrenheit will make it less attractive.

What you can also do is introduce predatory insects. Some insects, like ladybugs, hoverfly larvae, parasitic wasps, lacewings, and others naturally feed on not only aphids but also other plant pests. This method can be successful if you introduce them during spring and late summer as a form of prevention.

There isn’t a foolproof way to protect your crops from ever being attacked by these pests, but if you detect them early, getting rid of them will be much easier and more successful. However, do pay more attention during early spring and late summer as that’s when they’re in their prime time.

What You Can Do About Aphid Infestation

If you’ve found some of these little guys on your plants, it’s time to take action. First, prune off the infested parts of the plant and discard them right away. Then, rinse the plants thoroughly with water or water and vinegar solution to destroy any remaining pests.

Here’s what else you can do:

Organic Insecticides

As you may already know, chemical pesticides aren’t safe to use on hemp plants, so trying some organic options is much better.

  • Essentria IC3 is an organic insecticide that contains different horticultural oils. It can be used to control not only aphids but other types of pests, like spider mites and whiteflies. However, you will need to use it daily when you have an infestation as its effects only last for 8-12 hours;
  • Spinosad is another natural insecticide that contains one active ingredient – a soil bacterium. It’s an effective product that can be sprayed directly on the plants while the infestation lasts, but you can also put some in the water supply later to prevent future infestations.
  • Insecticidal soaps are great for spot treating any infested plants. They work for the most commonly found pests and are best used twice per day for the best results. Just don’t apply them to the hemp flowers directly.

Natural Treatment With Oils

Essential and horticultural oils are popular among some growers as an effective natural treatment against pests. Neem oil is one of them and it’s quite commonly used by growers for pest protection. 

However, other essential oils you can use are eucalyptus, rosemary, lemon, and cinnamon oil, all of which are said to be pretty effective. To use essential oil for pest control, just mix some of the oil with water and mist the plants with the mixture, but avoid the flowers. As for horticultural oils, canola, soybean, or cottonseed oil are all great choices.

The Takeaway – Early Intervention Can Solve the Problem

Spotting aphids on your hemp crops can really dampen your mood, but don’t despair. As long as the infestation is within a manageable range, there are many products you can use to save your garden and prevent aphids from ruining it next time. Being informed about how important early prevention is, is the most important thing, as aphids are really common. But, taking timely action can save you a lot of trouble.

A passionate advocate for the benefits of cannabis. Fraser Horton, who has a background in botany and a strong love of nature, has spent years researching how cannabis affects the body and mind. He established Leaf Nation in 2020, where he has devoted himself to educating people about the legalisation of marijuana and its safe and responsible use. Fraser is committed to highlighting cannabis’ potential for improving wellness and working to dispel the stigma associated with its use.


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