There are several insects (as well as other wildlife) a plant can fall victim to when growing outdoors. Here you will find explanations of common pests and methods for repelling them.

Spider mites

Common Insects

Spider mites

If left for too long spider mites will begin producing webs on the leaf surface, this should be addressed as soon as possible.

Thrips

Thrip damage

Thrips are mostly recognizable from the damage they do to leaves.

Aphids

Aphids

Common solutions

Neem oil

Neem oil can be added to feed water to repel insects such as spider mites or thrips. Be aware that it has a delayed effect and should be applied preventatively.

Insecticidal soap

A soap that can be used to kill insects. Less aggressive than a pesticide and some can be made using household ingredients

Predator insects

It's possible to add "good" insects that will hunt the insects you want to remove. This is only recommended for outdoor grows.

Some example predators for spider mites are Phytoseiulus persimilis and Amblyseius californicus.

For Thrips, you might use Amblyseius cucumeris.