Spider mites are any marijuana grower’s worst nightmare. This is because these pests are very difficult to eradicate. Many varieties of spider mites exist, but the worst by far is the two-spotted spider mite. This particular breed loves marijuana plants, so if you see one, you must come out with all guns blazing.
What are spider mites？
Spider mites are so devastating to weed plants simply because of their extremely high reproductive rate. Eggs hatch in just three short days, and five days after that the spider mites have reached sexual maturity. At this point, they will begin reproducing rapidly.
Why Are Spider Mites Dangerous?
There are two key reasons why you should worry when dealing with a spider mite infestation.
Disrupted Photosynthesis
First, as we have mentioned earlier, these pests feed on the chlorophyll within the leaves of your plants. Chlorophyll is essential for photosynthesis, which is how plants manufacture their food. By the way, full spectrum LED grow light can provide best spectrum for plant growth. When chlorophyll is destroyed, the plant gradually starves and can quickly die off.
Therefore, an infestation of spider mites has the potential to kill your plants if you don’t act quickly.
Developing Resistance
The second reason why spider mites are a problem is that at certain points in their life, they are immune to most killing methods. Much of this is because they are easier to identify once they are adults. They also may develop resistance if you don’t kill them all on the first attempt. If they return, you will need a new way to kill them.
Spider mites only need a few days to move through their entire life cycle, from being an egg to being able to reproduce. Once an egg hatches into a larva, it feeds for a few days, then hides away for a few days before a nymph emerges. That nymph, in turn, feeds for a few days before again hiding to mold into another nymph stage. The adult then emerges like a weed-devouring Spider mite butterfly.
Given that an adult female spider mite can lay at least ten eggs daily, an infestation can become full-blown in a matter of days putting your plants at high risk of being destroyed. Plus, their life cycle also makes it difficult to know when they are all gone. Say, for instance, you spray and kill off all the adults, you may not know that there are eggs or nymphs still there. Then, the next wave of spider mites emerges resistant to the treatment method you have been using.
That is why you can’t just kill them and forget them. You have to take a long-term approach and kill them multiple times.
Signs of spider mites on weed
Spider mites on weed can be tough to notice right away, making it difficult to get ahead of the game when it comes to eradication. They will appear like little dots to the naked eye, no bigger than the tip of your pencil lead. Many growers don’t notice that there is anything off until the infestation is big enough that it’s impossible not to see.
This is why it’s extremely important for you to do routine leaf inspections. Check both sides of the leaves to see any spider mite damage. Do this often, because you will need to have enough time to act faster than the speedy spider mites.
Spider mites generally live on the undersides of your weed plants’ leaves. Much like a “normal” spider, spider mites spin a web to keep their eggs and colony safe. You should be able to notice when a spider mite is making its home beneath a leaf because you will see fine white strings between leaves.
If you do, you will know there’s a problem to be dealt with. You also might see the fine silk on your plants’ foliage. This sticky silk will collect dust and dirt and will make your plant look dirty. It is especially common in a flowering room to see buds covered in this fine webbing.
The first signs of a spider mite problem will be seen on the leaves. Tiny specks will begin appearing – these specks are actually little bite marks from where the mites took a chomp of your plant. These spots might be yellow or white in color.
If a weed plant is badly infested with spider mites, the whole thing will start looking sickly and discolored, and could eventually just die.
Prevention of spider mites on weed
There are several ways you can prevent a major infestation of spider mites on your weed plants. If you use an organic compost mulch, for instance, you will be unknowingly adding predatory mites to your plants’ defenses. These beneficial mites eat the spider mites.
How to Kill Spider Mites?
They are different ways to get rid of spider mites including organic and inorganic ways. It’s actually easy to kill them, but the problem is that they come back with a vengeance. It’s also important to get rid of the eggs. Spider mites have an amazing ability to reproduce faster than you can count them. Within a week, they can destroy an entire crop, so pay special attention to eggs on the soil.
They become immune to pesticides quickly, which is why it’s recommended that you repeat the process every single day. Also, a combination of several methods described here should be followed. Spray liquids only when the lights are off to prevent the leaves from burning.
Before using any method, remove the infected leaves. It’s better to even remove infected plants that cannot be rescued since it gives other plants a better chance to survive. Don’t make the mistake of composting those leaves. Rather, just burn them.
Try to use these methods when your autoflowers are still in the vegetative stage since it’s extremely difficult to get rid of mites in the flowering stage. Mites don’t distinguish between photoperiod and autoflowering cannabis strains – they treat them equally. So, whether it’s a photoperiod or autoflowering strain, the damage should be controlled before the plant begins to flower.
Also, buds taste a little different if liquids are used on them. If you absolutely must use any of these methods during the flowering period, spray the buds and plants with plain water to get rid of the pesticides.
Organic Methods
Remember to use a combination of several methods described here. Also, spray liquids on plants only when the lights are off to prevent the leaves from burning.
Soap Water – This is perhaps the cheapest way to get rid of most pests but certainly not the most effective. Simply mix a drop or two of castile soap or any insecticidal soap with a liter of water and spray away. Spider mites tend to slip and fall due to the soap.
To be extra careful, wipe individual leaves with a moist towel soaked in soapy water. It’s best to repeat the process every day since this method isn’t as effective as other commercial products. Even the soil should be sprayed to kill all the eggs. What's more, you should know that grow tent ventilation is important.
Neem Oil – The simplest way to kill mites is to use Neem Oil mixed with a little dish wash soap. You can get neem oil online or in your local store. All you need to do is follow the instructions; however, be careful not to kill the plants because it’s pretty strong. Start with minimal amounts until you’re sure the plants can handle it.
General Hydroponics Azamax – Safe and natural to use, growers swear by Azamax. The best part is that it doesn’t hurt the plants or roots but only targets gnarly mites, fungus gnats, aphids, thrips, and several other pests. Spray the leaves, stems and every part of the plant including the soil to kill the eggs. Repeat the process every other day even if the mites are gone because they usually come back stronger.
Spinosad – Another organic product, Spinosad is nothing but fermented bacteria that kills spider mites immediately. Safe to be used around pets and children, it can be mixed with fertilizers although it’s best to use any pesticide separately. Spinosad infects the pests’ nervous system, and unlike other pesticides that harm beneficial microbes in the soil, Spinosad is perfectly safe to use.
Essential Oils – Some essential oils like Rosemary and Cinnamon are particularly effective in getting rid of spider mites and other pests. As always, a little soap mixed in will work. Organic products are amazing but they should be used with care since the plants could get affected if the oil remains on the leaves.
Rubbing alcohol – Not exactly organic, but rubbing alcohol or isopropyl alcohol mixed with water can help. Prepare a 50:50 solution of alcohol: water and spray. Some growers use the alcohol directly without diluting it but that might do a number on the plants. Alcohol tends to evaporate pretty quickly so the plants are pretty safe.
If you’ve tried everything and it still doesn’t work, pesticides made with toxic chemicals may be the only route for you. But, remember to use such products with extreme caution because they aren’t safe around pets and children. Also, wear a mask while spraying since they are dangerous. Once you harvest the buds, spray the grow room with a bleach solution to prevent further attacks.
Final thoughts
If you’re growing indoors in a marijuana grow tent, it’s important to determine where exactly your spider mites came from. This is a good thing to do before you start using everything in your power to destroy them.
Were the spider mites just randomly brought into your grow room from the outside? They could have come from a vegetable garden, from animals or your pets, or from another plant that isn’t marijuana. If they were just tracked in from outside, they most likely they are your standard non-super spider mites, so you can go ahead and use a simpler home remedy to take care of them.
Spider mites on cannabis plants
If, however, they came from another marijuana grower, you may have a tougher time killing them. If they came from clones you used or maybe were somehow tracked in from someone else’s marijuana garden or any other situation where the spider mite was living on someone else’s weed plants, then this is not a run-of-the-mill spider mite.
Instead, this is a marijuana expert. If they are two-spotted spider mites, you will have a very difficult time with them. They are probably already immune to lots of eradication methods. You should, therefore, use the strongest remedies immediately. Don’t wait around and play games, or your entire crop could easily get destroyed.
Remember that weed plants with strong genetics have less chance of getting sick and are less vulnerable to pests and diseases. So make sure to buy cannabis seeds from a trusted seed bank. Lastly, if you are a beginner, ECO Farm marijuana grow kit can be your great choice.