I've been really fortunate to never have any amount of bothersome pests- never even seen a spidermite in real life thank god. Worst case scenario is ants sometimes live in my pots and my plumeria trees are susceptible to whitefly. I keep my pots upstairs on a balcony so perhaps it keeps them up above where some of them will come. There is something you could probably do to sterilize your soil. You could lay it out on a flat surface like a slab or wherever makes sense. Mist it with water then cover with a clear sheet of plastic like a disposable painter's tarp and let it heat up in the sun for a few days. It should get hot and steamy enough to kill everything that might be an issue including weed seeds. I have a pressure cooker and have considered sterilizing some iffy soil with it, but it would take a while to sterilize more than a pot's worth as it only holds 8 quarts.