Mites suck the life out of marijuana plants, punch suckholes in your leaves, spread viruses and other pathogens, build webs on your buds, and can take over and ruin your marijuana garden in only a couple of days.
If mites take over your garden, expect your plants to stall, get sick, suffer, and look terrible. If you’re in bloom phase and mites appear, you better stop them fast, or your plants will produce lousy, tiny buds that look like dirtweed marijuana and lack THC.
I’ve tried almost every method for stopping mites after they’ve gotten into a hydroponics marijuana grow room. Neem, cinnamon, garlic, insecticidal soap, diatomaceous earth….you name it, I’ve tried it.
What I should have done first is to grow my marijuana in a Controlled Environment Agriculture (CEA) sealed hydroponics grow room that locks mites out using air filtration and other strategies.
CEA includes keeping your grow room temperatures at 74F or below, and humidity between 50-60%. Spider mites like hot grow rooms with low humidity, so give them an environment they don’t like.
I also should have dipped all incoming clones in a natural miticide such as Azamax, and made sure not to bring in mites from grow rooms that are infested.
Mites hitchhike easily, and they appear as live organisms of varying ages, as well as eggs that can survive long after the parents are dead. This means you kill one generation of mites…but those mites laid eggs before they died, and those eggs later hatch so you have to spray for mites over and over again. It’s a constant battle unless you use the interventions I suggest below.
Early detection is essential. Look at the undersides of your marijuana leaves every day, using a strong magnifying glass. I especially recommend Eschenbach magnifying devices of 10X or higher. The ones that have built in lighting are the most useful.
You especially want to look for leaves that have tiny yellow-orange spots on the leaf’s topside. These are signs of mites underneath.
As soon as you see any mites at all anywhere in your grow room, hit them hard. I have a three-part program. First I bomb the grow room with a pyrethrum fogger…
Turn off all your vents, lights and air conditioning, trigger the fogger, seal the room door and get out. Let the fog sit in the room for at least five hours, if not for an entire lights-out cycle.
Second, feed your plants Azamax, and spray them with Azamax. This systemic miticide enters your plants via roots and leaves. It kills mites when they first start sucking on your plants. It is not a contact “knockout” killer. That’s what the pyrethrum fogger is for.
Third, if some of your marijuana plants are especially infected with mites, move them out of your main hydroponics room after your pyrethrum fogger phase is over. Keep an especially close eye on these plants. You may have to give them extra doses of fog and/or extra strong doses of Azamax, to kill all the mites. Another anti-mite strategy includes feeding your motherplants and other marijuana plants with a preventive dose of Azamax.
A Big Buds reader wrote us about a pest-killing strategy in which you completely close off your grow room and flood it with 10,00 ppm of C02 for 15-45 minutes.
I failed to recommend this strategy in my original version of this article for several reasons. One is that generating that much C02 could be costly; many growers do not have C02 equipment or if they do have C02 equipment it is not able to put out that much C02.
Another reason is that 10,000 ppm C02 is toxic for humans and plants. It will not kill your hydroponics plants, but it can damage them.
Growers who have used this method indicate that it has to be done as a series of 2-3 treatments so you kill all adults, then 2-4 days later you do it again to kill babies that have hatched from eggs, and then perhaps 2-3 days later for a final killing blow.
The C02 kill method must have worked well enough for it to attain folklore status in the marijuana hydroponics industry. In recent years, however, growers report that the C02 kill method doesn’t work so well, especially for root zone pests. It is no longer seen as a guaranteed pest control intervention.
You can also select marijuana strains that are known to be resistant to mites…
For example, I recently grew out a room that had 25 Bubbleberry plants and five plants that were a cross between Bubbleberry and Sage-Sour Diesel. Ironically, the Bubbleberry plants described by Bubbleberry breeder Sagarmatha as “mite-resistant” were plagued by mites, but the Bubbleberry/Sage-Diesel crosses had no mites at all!
Armor your plants during grow phase and early bloom phase by foliar spraying and root feeding a product called Rhino Skin. It contains potassium silicate that makes your plants harder for mites to chomp on.
Wondering how long into bloom phase you can use Azamax, pyrethrum or other miticides? Ask the manufacturers of those products before you make a decision.
And never use Avid or any other chemical poison on your plants. Most chemical miticides stay on or in your crops and can make your marijuana unfit for human consumption.
The interventions I use are said to be “safe,” “natural” and “organic.” And I recommend that you detect and completely defeat spider mites before your plants are more than four weeks into bloom phase, even if you are using safe, organic, natural interventions. Because after mid-bloom phase, anything that gets onto or into your cannabis buds is likely to stay there and affect your marijuana quality, taste and aroma.
Keep pets out of your grow room, and remember it’s way easy to bring mites into your room on your clothing, body and tools. If you have a buddy who says he has mites in his grow room, totally avoid going to his house. You are almost sure to get mites on you, and they will transfer into your grow room.
Mites are one of marijuana’s most persistent enemies. Keep mites out of your hydroponics grow room and off your marijuana plants…or use the strategies I suggested earlier in this article if mites have invaded. You can defeat mites, but only if you detect them early enough and take decisive steps to kill them before they kill your marijuana heavy harvest dreams.