A Beginners Guide to Pests

A beginners guide to Pests

For anyone who’s growing outside or in a greenhouse there is a constant risk of pests. Unfortunately, bugs like plants and there isn’t a whole lot we can do about that. If bugs and pests get into our crops they can decimate the whole thing in a matter of days. Though we can’t completely remove the threat of creepy crawlies we can take steps to reduce their access to our plants. Much like mould, spotting the pests isn’t always enough to save the plants. We may not always be able to stop the infestation, but it does help us understand the kind of threat our crops are under for future plants. Of course, some steps can be taken to reduce the threat and potentially save our babies. Today we will have a look at a few of the most common beasties in a cannabis crop and what can be done about them.


These tiny little bugs are common in gardens and have been the bain of gardeners for as long as anyone can remember. They are teensy and yellow and will usually be found underneath the leaves (shown in image above). One of the reasons for their plague status is how quickly they breed. A female can have 12 sets of babies per day, and like most babies, they come into this world with an insatiable hunger. Check for aphids if the cannabis leaves are beginning to wilt and turn yellow.

Unfortunately chowing down on the leaves is not all of the damage that aphids do. They can carry disease like tiny exoskeletoned plague rats, bringing illnesses from previous plant victims to the cannabis plants. Their poop is an ant magnet, so it’s easy for aphids to just build an even more intense infestation that will destroy plants in no time.


There are a couple of ways to get rid of these nasty boys, but there is no way to guarantee the plants will be saved. Firstly we can home make a spray with a mixture made from tomato leaves and garlic soaked in water and mineral oil. Spraying this on the leaves should drive away the bugs, but watch it isn’t too strong or it can damage the leaves. Another way to get rid of bugs is to introduce another bug, sounds strange I know. Ladybugs and parasitic wasps are considered to be beneficial bests and will get rid of the aphids without damaging the plant.

Spider Mites

These little brown bugs have between 6 – 8 legs that can be spotted by all the little yellow and white spots all over the leaves. This is because they snack on chlorophyll in the plant, ruining the plant’s ability to photosynthesise. This can quickly lead to stunted growth or even plant death as the leaves can no longer create energy. Spider mites can also be spotted by the tiny silky strings they leave all over the plants. These webs can be a complete nightmare as they are almost impossible to remove. If these webs get right up in amongst the buds it can render them completely unusable.


These are very much pests that are best avoided altogether. Making sure the growing space is clean, fresh and that the soil is sanitary will keep spider mites away. Keeping clean as the grower can also stop pests from travelling into the grow room or space. Biopesticides can be used if it’s too late and the bugs are already in the plants. Using a powerful hose (as long as the plants are not flowering) is also a good idea. Keep cleaning the plants for a few days after the initial ousting the make sure there are no babies left.

Fungus Gnats

These boys are not tricky to spot as they appear as a sort of biblical swarm. They are small, dark and will fly about the plant and the soil showing off their destruction. They will lay their eggs in the soil, making it difficult to completely get rid of them. These boys are unlike the other bugs that chow down on the leaves and buds of the plant. They will use the nutrients in the soil to feed their young which deprives the plant of food from the source. By mucking around in the soil they also reduce drainage and can damage the roots, causing issues with mould and starvation further down the line.


Since the gnats lay their eggs in the top layer of soil this is usually where to strike if we want to kill them off. The soil needs to be moist to support the new larva so keeping this top layer of soil dry as a bone should kill off the eggs. Pair this with blocking off the soil with a cloth or sheet so that the females can’t lay any more eggs. Since the adults don’t want anything to do with the plants themselves this should get them to move on to find moister pastures.


As with mould the best way to save your plants is to stop the infestation before it starts. Keeping plants protected with netting, closed windows and door inside, and growing companion plants. These plants will attract pests to save precious cannabis plants. Pepper, garlic and mint plants usually act as the best companions as they will also drive certain types of pests away. Sterilising the soil is also a great way to protect cannabis plants. This makes the soil an unattractive breeding environment for a wide variety of creepy crawlies. If they can’t lay their eggs in the soil they likely won’t bother hassling the plant.

Learning how to avoid pests, remove pests and treat plants is a vital part of growing. Learning too late will only ensure that the current crop will be sacrificed to learn how to protect the next crop, which isn’t what we want. As always do plenty of research before starting to grow and keep your plants safe.

Remember: It is illegal to germinate cannabis seeds in many countries including the UK. It is our duty to inform you of this fact and to urge you to obey all of your local laws to the letter. The Vault only ever sells or sends out seeds for souvenir, collection or novelty purposes.

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