Companion planting is a way to repel insects you don’t want
in your garden – without chemical pesticides. It’s the way it used to be done –
you add plants to the garden which repel bugs.
Here is a quick overview of some useful plants.

Marigolds are pretty and popular plants which have the added
benefit of keeping parasitic worms at bay (sometimes even killing them) and
repelling whitefly.
Basil, sunflowers and chives are also good insect repellents.
If you have a particular bug or insect you’re worried about,
Google it and see which plants are best for repelling that particular problem.
Of course, you do also have to be wary about scaring away
the beneficial bugs you want to attract to your garden!
If you have a vegetable garden, consider planting nasturtiums,
petunias, alliums, tansy, yarrow, zinnia, lupine and geraniums – they will add
colour and beauty as well as protect your vegetables.
You can also use herbs for the same purpose - dill,
lavender, hyssop, thyme, tarragon, borage, chamomile, sage, fennel, caraway,
chervil, cilantro, lovage, oregano, parsley, peppermint, and rosemary are all
good, and they’ll add flavour to your dishes too!
Just be aware that some herbs (especially the mint family)
can grow quite quickly and aggressively and take over a lot of space in your
garden. You can always overcome this problem by planting them in pots or
containers when you then place close to your vegetables.
But don’t restrict yourself to only plants. Install a bat
house and some bird houses in your garden because they will all naturally eat
insects for you.