Most common pests which will invade your grow, and how to make sure you defeat them!

Nobody said growing is easy. On top of feeding your plants, keeping ph levels correct and creating the optimal environment to allow your plants to thrive, us growers have got enough on our plates. So when you throw insect invasions into the mix too, things can get even more tricky and risky to your plants wellbeing. This is a guide to the most common pests you may find sneaking into your grow, what they are, how to identify them and how to deal with them.

Red Spider Mite

Spider Mites are tiny insects, usually growing to a full size of 1mm which can make them extremely hard to spot. They thrive in warm environments with a low to medium humidity…so you can imagine how much they love your grow room!  From egg to adult takes around a fortnight at a steady 21 degrees and at 30 degrees, even less than a week!

Typically, the first sign of a spider mite infestation is damage to the leaves, this can come as a fine and pale mottling on the upper side of the leaf. Make sure to check the under sides of the leaf for tiny yellow/green mites, white skin casts and egg shells.

Once the infestation progresses you should notice the leaves starting to look mottled between the veins of the leaves and the leaves will start to dry out and curl. Once the infestation reaches a more critical stage you will begin to see a fine webbing appearing over your plants.

How to treat

There are some predators you can release onto your plants to deal with the spider mites, such as Neoseiulus Californicus, Phytoseiulus Persimilis and finally Amblyseius Andersoni, which will form colonies and fight them off.

We do strongly recommend the use of sprays, of which we sell a range on our website to naturally kill off spider mites. Also using a sulphur vaporiser could be a good idea as the fumes inhibits the spread of pests and also mildew and botrytis. In addition yellow insect traps will directly attract mature spider mites, diverting them from your plant, and catching the pests bringing them to a sticky demise.


Thrips are also tiny insects which can grow to a slightly larger size of 1mm-1.5mm. The easiest way to spot a thrip infection is to cut a yellow sticky trap into strips and lay them over the top of your pot. If this is particularly difficult with the type of pot you use, you can also place a whole trap as close to your pot as possible, as they are attracted to the bright colour it is still the same method.

Thrips pierce the leaf and then feed by sucking the cells out of the surface of the leaf. This causes silvery grey spots on the leafs with dark green excretion spots and can dramatically reduce the production of your plant, in some cases your leaves can wither and die off!

How to treat

Amblyseius Cucumeris is a predatory mite which mainly targets Thrips. They feed on young Thrip larvae and can also survive without the presence of Thrips and form a colony before the infestation have fully taken hold.

As with the majority of other pests, a number of sprays will help to kill off any Thrip infestation, you can browse them all here. Also be sure to use yellow sticky traps as these will work for any small pest.

Fungus Gnats

Fungus Gnats are notoriously difficult: especially in young plants. They damage seedlings, rootstock and cuttings of many plant species they are known as one of the most common household pests.

Adult Gnats are noticed when they start to appear in large numbers, their eggs are deposited in the soil. Larvae generally eat rotting plant material, algae and fungi which are present both in or on top of the soil.

Adult Gnats are tiny delicate black flies averagely around 3mm long with long antennae and legs. The larvae are legless and round about 4-5mm in size when fully grown, with clear bodies and black heads.

The adults are easiest to spot as they hop over the compost surface. Placing sticky fly traps over the sides of the pots will make them clearer to spot and to determine if you have a Gnat infestation.

Adults can spread fungal diseases but most damage is caused by the larval stage feeding on plant roots making them vulnerable to infections such as Pythium and other damping off diseases. 

How to treat

Steinernema Feltiae is a microscopic worm like organism which actively searches for Fungus Gnats and forms a colony inside of them. You can release these onto your plant as they feed on the contents of its prey (Gnats) and kill the larvae within a few days.

Once again our selection of sprays and pest killers will make sure the job is done, without damaging your crop.


Aphids grow to just a quarter inch as adults, and may appear invisible, in that case it’s extremely important to scan over your plants closely and often, to distinguish any insect invasion so you can treat it early. Aphids can come in a range of colours so you should keep an eye out.

Aphids tend to favour buds, the underside of younger leaves and shoots. Plant growth can be affected by Aphids and leaves may become disrtorted and the plants general health will deteriorate.

Aphids may leave a sticky dew like substance on your plants so it’s important to keep an eye out.

Lady Bird Larvae is a biological control for many Aphid species, both adult Lady Birds and it’s larvae will feast on the Aphids. You should add these earlier into Aphid activity before they grow too big, particularly when the plant is young.

As always yellow sticky traps and our selection of sprays and solutions should definitely get the job done, but each grow room pest has biological ways of being dealt with, in the form of other predatory micro organisms.

Due to demand we only sell a wide selection of sprays and solutions, sulphur and sticky traps, but these work quickly and effectively in tackling your infestation. Our staff are very knowledgeable so any questions/problems you face, we can help you instore.