How to Get Rid of Spider Mites
Spider mites can be extremely difficult to get rid of once they’ve infested your grow area, especially if you’re growing indoors. This plague is especially ferocious; they start off as just a few but soon there’ll be thousands of them and they’ll end up completely killing off your plant. Outdoors there are many other insects that feed off of these spiders, so it’s much easier to keep under control outdoors, however indoors these insects are fatal for your plants; high temperatures and high humidity make these pests reproduce at a ridiculous rate. These mites aren’t actually spiders, but we call them spiders due to their appearance and the webs they weave around your buds. There are red spider mites and white spider mites.
Once they get into your grows they make your plants their headquarters and home, beginning with the weakest plant and moving on to the next. It’s almost impossible to see the first few mites on your plants; you’re going to need to be on the ball for this one. Once they’ve taken over one of your plants, they’ll move to the next one and so on. Even if you remove the plant that has the most mites on it, there will always be a rogue mite that’ll go to the next plant and start the infestation all over again. They weave webs at the base of the trunk and the tips of the branches, laying eggs inside the webs. Many people don’t even realize their plants are infected until they go to spray them and the water makes the webs visible.
These little guys are everywhere in nature, but if they’ve found their way into your house it’s most likely because you brought it in on a clone or another plant. Those that have had grows infested with mites and haven’t completely irradiated them tend to actually make the mites immune to whatever they’ve been using, and then there’s absolutely no way to get rid of them completely. Make sure you check all clones that you’re given for spiders, mites, fungi or eggs, as these can easily spread and ruin your entire grow.
The best way to avoid this outdoors is to prevent it from happening in the first place by spraying your plants with neem oil, which protects your plants due to the fact that it smells extremely venomous to all kinds of insects, so they’ll go to any other plant but yours. Indoors this changes of course, as the mites have no other plants to attack if mites get in, so if you use neem oil indoors it probably won’t work that well.
When you plant indoors and have a high mite risk factor, then the best thing to do is to use abamectin, a product that’s widely used as an insecticide during the growth phase and the start of the flowering phase but no longer than that as it’s a chemical insecticide and the smell and flavor can stick around in your plants for a while. It’s extremely efficient in getting rid of mites.
People tend to be of the opinion that it won’t happen to their plants until boom, one day their plants are covered in these little pests due to the fact that just one mite can lay three to four eggs a day, meaning that in their 30 days of life they lay up to 120 eggs, and three out of four will be female, continuing the cycle.
It’s much easier to get rid of them outdoors than it is indoors. Once you’ve detected the infestation outdoors, with a couple of sprays of abamectin you’ll get rid of most of them, and the rest will most likely be eaten and killed off by other insects. However, indoors you’ll need to be extremely careful or you’ll end up with immune, immortal mites. At 30ºC new generations of mites are born every week, and every 15 days at 23º, so you’ll need to apply abamectin to get rid of 2 or 3 generations before they’re all gone. At 12º degrees they get slower, and at 40º they stop growing completely.
How to spray your plants and get rid of the infestation:
It’s quite easy to do; you just need to mix the insecticide with water according to the ratio stated by the manufacturer every certain amount of days depending on the temperature to attack newly born mites and the adult ones, which will die once they’re old, although there’s a more effective way to get rid of them.
This consist in spraying the plants with potassium soap (this is no longer available to buy but you can make your own) an hour before using the abamectin. This soap basically cleans your plants of fungi before using a fungicide, or as a wetting solution so that what you spray next is absorbed correctly. In the case of these mites, its use is slightly more interesting; it makes their exoskeleton much softer, which makes it much easier for the insecticide to penetrate their bodies; if they don’t die off because of the insecticide, they’ll die off due to how weak the potassium soap makes them.
You’ll need to apply the insecticide properly, adapting to the temperature of your grow; a 28ºC grow won’t need the same parameters as a 24ºC grow. Here’s a list of how many days you need to spray depending on the temperature of your grow, making the treatment much more effective. You should never apply it more than three or four times in a row using the same formula, as you can create resistance in the mites and they’ll end up being immune. When applying, you’ll need to properly soak the underside of the leaves and the top. Also, if you find any webs, remove them so you can kill the little pests hiding underneath. (temperatures in celcius)
- 23º – Apply the product every 14 days
- 24º – Apply the product every 13 days
- 25º – Apply the product every 12 days
- 26º – Apply the product every 11 days
- 27º – Apply the product every 10 days
- 28º – Apply the product every 9 days
- 29º – Apply the product every 8 days
- 30º – Apply the product every 7 days
Keep in mind that you’re going to be consuming the end product, so the last spray should be at least 15 days before harvesting to avoid any strange flavors and aromas in the final product. Personally, I spray during the growth period and more or less until the second week of flowering, as the buds start to appear; even if the infestation was to happen at that time, it wouldn’t have enough time to reproduce and spread before harvesting time.
When you have plants in a permanent growth period like grow rooms with mother plants, the best thing and the most natural option you have is to use a sulfur burner, that can protect your plants from all kinds of insects and fungi. We have a whole other article about how to use sulfur burners, go check it out.
There are also many natural predators that can get rid of mites like another type of mite, Californicus. These mites eat red spider mites, and they especially enjoy eating the eggs and the younger mites. They’re usually quite expensive to purchase, but it does avoid the use of insecticides and pesticides.
Sometimes we’re left with no other option than to sacrifice a few plants to keep the rest of specimens alive. In this case, you can take a clone from the infected mother plant, take them all of out of grow room as well as old pots and anything else that’s in there, clean everything thoroughly with bleach and disinfectant for mites and fungi, and begin your grow room again with that clone which will be much easier to treat and control.
If you really don’t want to have to deal with devastating infestations, the best thing to do is to prevent it from happening in the first place. If it’s too late, then you need to do everything you can by using the products we talked about today. If you can’t get rid of it, remove all of your big plants which are where they tend to hide, and try it again. I know people that have had these little pests in their grow rooms for three years now, and they still can’t completely get rid of them and are unwilling to remove their mother plants and start again, ending up with an endless stream of immortal spider mites, as well as spreading them to other grows through clones. Let’s hope this doesn’t happen to you.
Author: Javier Chinesta
Translation: Ciara Murphy