spider mites on flowering cannabis

How to get rid of spider mites during flowering

How to get rid of spider mites during flowering, once and for all!

We’ll walk you through exactly what you need to do to get rid of spider mites during flowering, but the most important thing is that you act FAST.

If this is a familiar sight to you, then you’re no stranger to Spider mites and the havoc they wreck, these nasty little buggers can cover an entire grow overnight, seemingly from nowhere, and if you’re afraid of spiders – a real-life nightmare.

But don’t panic, If acted upon quick enough, you can eliminate them and their eggs and save your crop.

What are spider mites?

Spider mites are typically less than 1mm (0.04 in) in size and often vary in color. They spread rapidly by laying tiny, initially transparent eggs and most species spin silk webbing as a form of predatory protection.

This is where the name spider mites comes from. They are actually part of the Acari (mite) subclass and are not the “Spiders” we know of.

Spider mites thrive in hot and dry conditions, much like a flowering room or tent. Under perfect conditions (around 27c or 80f), the spider mites can hatch in as little as 3 days from being laid and some species can become sexually mature in as little as 5-7 days!

A single female mite can lay up to 30 eggs per day, for approximately 30-60 days until the day they die, that’s around 900 – 1800 eggs per mite, hence the explosive overnight infestation that often occurs.

How to get rid of spider mites during flowering:

So your plants have reached the flowering stage of their life cycle, you have likely invested your time and money to get them where they are today, only to be struck with an infestation seemingly from nowhere.

When your plants are in the flowering stage, the last thing you want to do is use any harmful chemicals, fungicides or insecticides, typically the traditional spider mite removal methods aren’t suitable for the flowering stage as chemicals tend to leave residue and alter the taste of your buds, even more so if applied during the late stage of flowering.

Using CO2 as an effective chemical-free, organic solution:

Whilst CO2 is non-poisonous, you can use it to replace the oxygen in the air, this will deprive the mites of essential oxygen, effectively suffocating them, leaving no residues on your plants or equipment.

This won’t cause any harm for your plants, in fact, a boost of CO2 might help them deal with the stress of damage caused by the mites.

What you’ll need:

  • CO2 Cylinder(s) as well as a Regulator to control the flow
  • Vacuum Cleaner
  • a CO2 Meter to measure the PPM
  • Clean Brushes

How to get rid of spider mites during flowering:

    Make sure that your grow area is sealed as well as you can, tape any cracks in the windows and doors

Any cracks in the doors & windows will allow oxygen in and defeat the objective, so this is essential.

Set your CO2 meter for 12,000 ppm

If you’re using a grow tent, set the ppm to 15,000 – this will allow for any leaks, If your CO2 meter doesn’t go this high, you can use a calculator.

Calculate the amount of CO2 you will need for your grow space, switch off any exhaust fans.

For example, a 1000 cubic feet grow tent will require 12 cubic feet of CO2, use this calculator for an accurate calculation.

Switch your CO2 generator on and leave the room

Uhm, if you don’t leave the room at this stage – you’re gonna suffocate and die… so this is pretty important

After your generator has finished pumping in CO2 turn the exhaust fans on before entering the room.

Let the exhaust fans run for at least an hour before entering the room, otherwise, you run the risk of carbon dioxide poisoning.

You can now enter the room, begin cleaning the webs and dead mites with a vacuum cleaner, you may need to get a clean painters brush and brush upwards to make sure that you get all the webs off your plants.

You will want to repeat this entire process in 5 days to kill any dormant eggs that have now hatched to permanently eliminate the mites.

Spider mites can appear from nowhere practically overnight, luckily we have a chemical free, organic method of getting rid of spider mites during flowering.

Spider Mites 6 Weeks in Flower – Only Getting Worse

Got some plants 5-6 weeks into flower and I’ve been trying to fight a mite infestation that only seems to be getting worse. I’ve bombed the room with Doktor Doom foggers 3 days apart 3 times now. I also did a light spray on the plants, but 5 weeks in seems a little to far to be spraying anything. Or is it? I know Azatrol is safe up to the a few days before harvest, but is it going to damage the buds this late in? Rosemary oil, perhaps?

Thanks for the help. I need it soon!


is avid safe to use this late into flower? maybe a lower dosage?

the plants are in a 3×6 tray and trellised, so moving them isn’t so much an option

Living dead girl

What? NO! Don’t use the Avid right now. Your best bet is going to be two or threefold. First, CO2 at high ppms, during lights OFF (I think my son was doing around 5,000ppms to control his mite problems). Remember, CO2 sinks, so you want your girls close to the ground for that.

Second, he put GREEN bamboo stakes into the pots with his plants and blasted them with fans. The mites got off the plants and crawled onto the bamboo stakes, where he was able to remove them physically.

You can try Azamax/Azatrol, but you really need to soak the girls, really be certain you’ve hit every millimeter of space. At this point I wouldn’t worry too much about mold or rot if you have RH under control.

Finally, you can raise the humidity, and I’m talking high, around 80%, and believe you me, they do not like it.

Max Powers

You can try vacuuming them off with the correct hose attachment.

My buddy used Organcide in 6th week of flower. It almost eliminated the mites (thought they were gone completely but saw there were still some at harvest) and the bud turned out ok. Taste was off a bit (it usually is with this guy, always having to spray cause he is lazy with preventatives in veg) but he was able to get a decent price for it.

If you are going to use CO2 forget about a controller just open the valve on the tank and close the door behind you. Try and seal the room the best you can. Your plants won’t be affected by the excess CO2. The bugs will.

No pest strips at Home Depot work for mites. They are controversial though as far as health is conserned. I would not use them in week 6 of flower. I know people who do though. Some people keep them hung permanently in their grow rooms. That is one of the reasons I grow my own. I know exactly what my buds have been exposed to.

Living dead girl

My experience with using RH was completely accidental and due to the way in which my garden became infected (via my visiting son’s clothing), the fact that I wasn’t running very good ventilation and was much more concerned with keeping the room warm at that time.

In any event the RH in my flowering room during winter stays well above 50% most of the time, it’s usually in the 60%-70% range, and during flood days (now that I have trays) it hits 80% easily. But in my veg-table (a raised box on wheels, sided with reflective-coated OSB, lit w/a combination of shop lights and CFLs) it’s usually 50% or below, and that’s where I discovered mites several weeks after my son visited. And in the worst way, by discovering stippling, looking further and finding webbing.

For some reason they never got a foothold in the flowering room, and since then I’ve made it a rather strict habit to always visit each area in one direction, i.e. I visit the flowering room first, ALWAYS, and then open up the veg-table. Everything’s easier to treat in veg, so that’s where I’m more willing to place risk and try stronger Txments.

I know a lot of people say you’re risking bud-rot and mold in the higher RH values, but my girls love it, and the only reason I have PM in either area right now is because it established during summer in a nearby veggie garden (which was also pretty badly infected with aphids). I’ve also suffered PM at lower RH values, and have seen it persist at values as low as 30%. I know that’s not the only issue, just as I know that someday I probably *am* going to see bud-rot or some other problem with the higher RH (just like I’m having RA problems for the first time ever), but for now I watch ’em like a hawk and try to learn as best I can.

Give me more grows under my belt and I may become more equivocal about it, maybe not. I know Jalisco Kid likes to run his rooms at a higher RH, though, and I believe he’s got plenty of seasons under his belt.

Got some plants 5-6 weeks into flower and I've been trying to fight a mite infestation that only seems to be getting worse. I've bombed the room with Doktor…