When planting a garden one of the thing you should take into consideration is the plants you add into your garden. Just like you, garden plants have friends & they have frenemies. This is especially important to consider when you're vegetable gardening because companion planting can make or break your vegetable garden. Some plants will help improve the crops of other plants and attract beneficial bugs into your garden and some will do the opposite.
I've already made a post about nasturtiums and the benefit they bring to the garden and urban farm. The root exudates of hot peppers prevent root rot in plants like tomatoes and cucumbers. If you plant climbing beans below corn they beans will use the corn stalks as a support system. beans also enrich the soil by fixing nitrogen. Keep beans away from onions as they are natural enemies.The common marigold you can buy at just about any garden center in Chicago is said to discourage beetles & white flies.