Aphids on marijuana plants

Aphids are winged insects that hide on the underside of your marijuana plants’ leaves, using their piercing mouths to bite a hole in your plant and suck the nutrients from the leaves until they yellow and wilt. They can be green, yellow, black, brown, or red. They have oval-shaped bodies, and you might be able to see their wings and antennae. Here’s our guide on what to do if you find Aphids on your marijuana plants.

Although aphids do consume precious nutrients from your plants, that is not the only reason they are problematic for your plants. They also might carry viruses and give them to your marijuana plants, and these viruses could in turn stunt your plants’ growth and slow down flower production. Some aphid species actually inject toxins into your plants – and this has a serious impact on your crop.

Recognize Aphids on marijuana plants
Recognize aphids on marijuana plants

Signs of aphids

Unlike spider mites, aphids are happiest at a temperature between 60 and 80 degrees Fahrenheit. When they snack on your marijuana plants, they drop a substance that is sweet and therefore called “honeydew”. The honeydew often results in sooty mold growing on it, which turns your plants’ leaves black and may attract ants. Therefore, aphids reduce your plant’s nutrients, potentially give your plant a virus, and attract other pests to come snack on your plant.

Signs of Aphids on marijuana plants
Signs of aphids on marijuana plants

The honeydew (aphid waste) starts growing sooty mold, which will build up on your plants’ leaves and branches, eventually turning them black. This is often the sign anyone notices of an aphid infestation that has been building for a while.

To protect the entire plant from pests, use Bergman’s Plant protector, which comes in a package of three bottles.

Marijuana plant protector

Bergman’s Plant Protector

  • Protect your plants from diseases and harmful pests.
  • Consists of three 20 ml bottles
  • Enough plant protection system supplies for up to 20 plants
  • Suitable for soil, hydroponic and all other grow mediums

The most important step in taking care of an aphid problem is noticing it early on. You won’t be able to predict when winged aphids might come and start producing offspring on your plants, but you can do a routine check at least once per week. You should keep an especially close eye on the areas around your plant’s buds, as well as new leaves. You will be able to see new aphid clusters or colonies, which indicates that these pests are already well established on this particular plant.

Not sure if aphids are causing the damage to your marijuana plants?

Check the article Marijuana pest and bug control for a list with pictures of all pests and bugs

How to get rid of aphids

Luckily for you, aphids are sometimes naturally taken care of with really serious infestations. Wasps will come and actually lay their eggs inside of the aphids, thus “parasitizing” these pests. The aphids start forming a mummy shell that is thin and crusty, at which point that aphid is not longer a danger to your plant’s health.

Ladybugs are another predator of aphids. If you suddenly notice a lot of ladybugs in your marijuana garden, you can be confident that there is an aphid problem. Don’t panic, however – the ladybugs will eat them up and get them back under control. This is Mother Nature’s way of dealing with overpopulations and infestations. You can buy 1500 live ladybugs online for only $9 at this link here

Get rid of Aphids on cannabis plants
Get rid of aphids on cannabis plants

While Mother Nature takes her course of action, you should take yours and help her along a bit. There are two home remedies that you can use as organic sprays to take care of your aphid problem. The first spray, tomato leaf spray, works especially well if you also are caring for tomato plants.

To do this, you simply combine two cups of water with two cups of chopped tomato leaves and let it steep for one entire night. You can then remove the leaves by straining the liquid, and pour the remaining liquid into a clean spray bottle, then add two more cups of regular water. You can then use this spray on the leaves of your marijuana plants – focus especially on the bottom side of leaves, where aphids like to live.

Another option for a similar mixture is finely chopping an onion and two garlic cloves, then blend them with two cups of water. Strain the pulp out and spray the mixture on your plants.

If tomato leaf spray isn’t your style, you can try an organic garlic oil spray instead. It kills all sorts of pests (one of which is aphids) and also has antibacterial and antifungal properties that will keep harmful diseases away. To make it finely chop three or four cloves of garlic and combine it with two teaspoons of mineral oil. This should be left to sit for 24 hours, after which you should strain it into a gallon of water, then add a teaspoon of liquid dish soap. You should then store the resulting mixture (i.e. in a plastic jug), and use only two tablespoons combined with a full spray bottle of water.

There are many measures that can be taken to prevent pests, but for those with limited time, I have created multiple grow sets which features all you need in order to grow healthy plants from seed to harvest!

Buy your grow set

With the garlic oil spray, you should definitely check that it won’t damage your plants before spraying the entirety of your garden with it. Take the solution in the spray bottle and spray it on one leaf of a marijuana plant. Then let it sit for one to two days and return to it to check if there is any leaf damage. If there is (characterized by yellowing), then you should dilute the mixture even more and test the solution on a new leaf each time. Once you successfully have no leaf damage, you can spray the full plant with it – once again, focus especially on the bottom sides of leaves.

A commercial product like Bug Blaster will always to the job. If you want to be sure to kill them all buy something like Bermans Plant Protector.

There are still more ways to control an aphid problem. You can use fatty acid salts or insecticidal soaps to disrupt the cell membranes of insects, therefore killing them. They don’t have any negative effects on your plants, and they need to be applied directly to the aphids. Other options include nervous system insecticides like malathion, Dursban (chlorpyrifos), and Orthene (acephate). These insecticides will claim on the label to be for shade trees and ornamental plants, but will also work for your marijuana plants.

With any of these substances, you may need to reapply it once. It is not recommended that you use Sevin, which could have a negative impact on those insects that you do want around (such as ladybugs, lady beetles, and lacewings). These bugs will keep aphids at bay.

To learn more about harvesting and protect your marijuana plants from various pests, download my Harvesting Guide.

Marijuana plant symptoms

How to recognize marijuana plant symptoms caused by aphids:

  • Leaves turning yellow in color
  • Leaves wilting
  • Plant wilting
  • Bugs
  • Aphid clusters or colonies on leaf undersides
  • Clusters or colonies near new growth
  • Clusters or colonies near buds

Aphids give birth to live offspring (rather than laying eggs) as much as twelve times per day. Female aphids are capable of producing between 40 and 60 offspring total, and this offspring will reach maturity within 7 to 10 days. This leads to a huge population boom. Hundreds or even thousands could be living and munching happily on your plant in a matter of weeks. Winged aphids only happen when the species is stressed enough (or has consumed enough of your plant) and needs to search out new habitats. It will do this by flying away (probably to one of your other plants).

Remember that plants with strong genetics have less change of getting sick and are less vulnerable for pests and diseases. So make sure to buy cannabis seeds from a trusted seed bank.

Faq about aphids on marijuana plants

What are the signs of aphids on marijuana plants?

When aphids snack on your marijuana plants, they drop a substance that is sweet (honeydew). Honeydew results in sooty mold growing, which turns your plants’ leaves black. So if you notice black leaves that means your marijuana is now infected with aphids

How to get rid of aphids?

Ladybugs love eating aphids, so if you see ladybugs on your marijuana plants, let the mother nature take care of it. But if you want you can buy live ladybugs online and use them against aphids

What is the best home remedy for aphids?

There are two home remedies that you can use to get rid of aphids: Tomato leaf spray and Onion & garlic spray. Both these sprays work really well against aphids.

Thanks for reading. Please leave comments or questions below and don’t forget to download my free grow bible.


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Mr Robert Bergman PhD


Robert Bergman is an Amsterdam-based marijuana grow expert who has years of experience from small grows to massive operations ... See profile

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25 comments on “Aphids on marijuana plants”

  1. I’ve been growing for years got aphids and spider mist yes Dawn detergent 2 teaspoons per gallon of water soak plants over 1half gallon of solution per plant I’ve got fifty so got at a pace 3 or 4 at time let dry completely set 20 min to suffocate and soften eggs hose hourly till branches are sagging they hate cold it’s 45 here right now so if u can leave sprinkler on over night they don’t like water eighter drowns them u might loose a few branches but small price to pay water will also wash them pain in the as bugs of plants repeat every 2 days for six days

  2. My marijuana plants are already pulled and I’m noticing aphids all over it and flies how do I get rid of them please help

  3. I was just wondering if the tomato leaf spray can be used during late flower. I am 6 weeks into flower and one of my girls has a moderately heavy aphid infestation. I’m searching everywhere and found this but nothing about being able to spray the whole plant, buds and all, or just leaves????

  4. I have been reading on peppermint spray. I have used a diluted spray of dish soap that works well but I have to rinse the plants again after 5 minutes to remove soap residue. Is it ok to spray your buds…does it effect the quality of your bud?

  5. Tom,
    Thanks for the wonderful share of your story. Glad nature went to work for you. 🙂 – I❤️GM

  6. Just checking back to say I actually didn’t need to make any kind of pesticide spray in the end. I hosed down the heavily infected plants a couple times (the Bougainvillea and another big plant), and used a little spray bottle to spray them off of the young cannabis plants’ leaves with plain water and that seems to have done the job. Nature appears to come and take care of this problem anyway. The day after I first noticed them I noticed there were a lot more wasps in the area. The wasps seemed to enjoy picking them off and then a day later I noticed some lacewings and ladybirds in the garden, so I’d say not to get too worried if you notice these little pests start to appear in your garden. Hose/spray them off your plants and they seem to die, leave nature to take care of the ones that are left.

  7. First time ever growing and I just started noticing them while watering, then I looked over to my Bougainvillea to see the horror. They were absolutely all over it. Pruned and sprayed the shit out of the Bougainvillea with the hose pipe which seems to have done the job but this wasn’t an option for my 1-month young cannabis plants, will try the onion/garlic/water mix tomorrow and see if I have any luck with that. I have noticed a number of wasps lately but they’ve been too focused on the Bougainvillea to notice the small amounts on my other plants. Lots of great advice here, thanks for the help!

  8. The garlic, onion and mineral oil absolutely worked (while you’re waiting on your bug blaster order). I’ve searched the entire www only to find out all I had to do is log into ILGM for all my growing needs!

  9. Spraying with what? You should follow the directions on the bottle of insecticidal soap, that you are using. Aphids thrive on the bottom of the leaves, and wiping them off with a cloth or light towel is best. You need to wipe off all the affected leaves,

  10. How often should I spray while battling aphids to ensure I get them all? And how do I tell if they’re dead or alive after I spray? Will they fall off when they’re dead?

  11. […] As mentioned above, the presence of ants in your cannabis garden is one of the best ways to predict a possible aphid problem. To get rid of aphids, there are a number of different options available. The best choice is usually an organically based spray that you can apply to the undersides of the foliage. Read more about Aphids on marijuana plants […]