Spinosad is an organic insecticide made from the fermentation of a specific soil bacteria ( actinomycete Saccharopolyspora spinosa ) and kills spider mites via ingestion or contact by affecting the insect’s nervous system. Spinosad can be a good choice for organic and outdoor growers, because it is very toxic to spider mites, but is less toxic to many beneficial arthropods. Note: Most spinosad products are effective for only about 24 hours after being mixed with water, so only mix as much as you will need per application. You will need a mister (also called a “One-Hand Pressure Sprayer”) to spray all the leaves evenly.
Essentria IC3 Insecticide is a mix of various horticultural oils which are organic and safe for humans. It is often marketed as a “bed bug killer” but it can be effective against many bugs, including spider mties, when the plants are treated regularly. Unfortunately, it only stays effective on the plant for about 8-12 hours so you will want to either apply this daily or (better idea) combine with other options. You will need a mister (also called a “One-Hand Pressure Sprayer”) to spray all the leaves evenly. Fatty acid salts or insecticidal soaps weaken the outer shell of spider mites but are safe for humans and don’t leave much of a residue. With soaps, coverage is very important as it does not stay on your plant for long, so follow-up applications may be necessary. Although this is considered safe, avoid getting any on your buds so it doesn’t affect the taste/smell!
This spray is hard on spider mites, but the main ingredient Pyrethrum can also be hard on plants, especially in tight spaces without much ventilation, so keep it as a last resort if possible. Use with extreme care around humans as the ingredients can be toxic. Never use Pyrethrum-based products on your plants while your grow lights are on as it can burn your plants. Avoid using Pyrethrum products on young or sensitive plants as they can get burned even when the lights are left off. Do cover your grow lights and vents when bombing your plants with Pyrethrum and make sure you give the area at least 24 hours to air out before you try to breathe the air. This spray can work well for a couple of plants, but you’ll want a Pyrethrum fogger if you have a lot of plants to treat. Outdoors, Pyrethrum can kill beneficial insects too, so keep that in mind if you’re using natural predators to control pests (like ladybugs). All that being said, this spray will work to get rid of most spider mites, and it kills them on contact. Pyrethrum kills spider mites but not their eggs , so this product usually needs to be used 2-4 times (once every 2-3 days) to stop the breeding cycle and get rid of the toughest infestations. These emit a vapor that kills spider mites but do NOT use these if you will be breathing air from your grow room as the vapor they give off is toxic to humans and other mammals. These are only suitable if you’re growing somewhere that is NOT your living space but can be an effective way to get rid of spider mites. Floramite – Strong stuff with harsh chemicals, incredibly expensive , but it can often do the job when everything else fails. Bleach solution (1 tablespoon of bleach to 1 gallon of 95°F, pH balanced, water in a spray bottle or mister) – make sure to clean all surfaces of your room, and bleach them too if possible. Alcohol and Water mixed together (9 parts water to 1 part alcohol) will also kill the bugs on contact and shouldn’t hurt the plant. SM-90 mixed with water (1 part SM-90 to 5 parts water) kills spider mites on contact and is organic (it even smells good!). You will need a mister to get nice even coverage on all the leaves with SM-90. Neem Oil works in a similar way to SM-90, though Neem oil doesn’t smell as nice and will leave an unpleasant taste/smell on buds when used to treat flowering plants. There’s some evidence Neem oil may be harmful to humans so use with care! Just as with SM-90, you will need a mister to get all the leaves evenly, especially since neem oil and water will separate easily. Insect predators – there are also insect predators such as ladybugs and predatory mites that can provide some control and reduce your spider mite numbers, but it is unlikely these will get rid of your spider mites on their own. Insect predators can be effective if you have a small problem or if you need to get to harvest and chemical sprays are not a good option. Diatomaceous Earth – Basically, this is fossil dust – sprinkle on the top of your soil, and anywhere else in your room (window sills, doorways, etc). This powder-like substance is harmless to mammals and plants but is incredibly sharp at the microscopic level. Therefore it will tear and dehydrate spider mites on physical contact.
This will not get rid of an infestation but can help control and slow things down when used effectively. Treat Entire Grow Area With Insecticide, Not Just Plants! – Treat complete room with broad-spectrum insecticide (only do this for a really bad problem or one that keeps coming back) – avoid this if you can! Note: Many growers try to avoid chemical sprays or miticides which contain Abamectin or lindane because these are harmful to humans. Please take a look at anything you use to treat your grow room, follow the directions closely, and heed all warnings. Some treatments will work for some setups or types of mites, but not for others. As mentioned earlier, if you got your spider mites from another marijuana grower, chances are you may need to resort to extreme measures to get rid of your infestation. Step 2: Follow up in 2-3 days with a different method to kill them (you should also re-apply your first method) Follow up in 2-3 days with something different that will also kill their eggs and any surviving adults. The adults at this point will already be more resistant to your original method so you’ll get the best results using something else for the second treatment.
Step 3: Repeat Step 1 & 2 at least one more time – always treat grow area at least once after you think spider mites are completely gone. Repeat steps 1 & 2 at least one more time to ensure that you have really cleaned out your grow room. Some species of spider mite can take days or weeks to mature and will reappear in the grow room stronger than ever. Because of this, you should treat your area at least once after you are almost certain that all the spider mites are gone. Using a mix of several different methods seems to work best for getting rid of spider mites.