This is not as contradictory as it might seem at first. To garden sustainably and with a minimal use of pesticides, you need several things. First of all, you need good soil for your plants. Then you need the other requirements the plants need, such as sun and sufficient water. After that, mimic nature's wisdom as much as you can. For example, plants in nature do not exist in a monoculture. Without sufficient diversity, plants often lack what they need regarding insect life around them. For example, almond-growers in California fail to plant enough flowers around and in their fields to support honey-bees year round. As a result, honey bees have to be transported from all over the country to pollinate the trees. Otherwise there would not be enough bees when the almond flowers are in bloom, so yields would be greatly reduced. Transporting the bees is tough on the bees and uses a lot of fuel, so diversifying the monoculture would be kinder and more environmentally sustainable.
A variety of flowers around and in your vegetable beds will mimic nature. This will attract beneficial insects such as ladybugs and parasitic wasps to feast on any caterpillars or other "bad" bugs that would otherwise take over your garden. By avoiding pesticides, you avoid accidentally killing the beneficial insects that will turn the pests into a tasty meal.
This year I plan to put mint plants near my garden beds when they are blooming. I also have sage blooming in my yard. I have just started four hanging baskets: two seeded with impatiens, which grow well in shaded areas under our trees, and two with California poppies. The poppies seem the right size for baskets and are said to withstand drought well. Within my garden beds I plan to plant dill, sunflowers, marigolds, and nasturtiums. I have some other seeds I bought on impulse because they were 25 cents each at the dollar store, and I will be adding those to my vegetable-garden plan as I have time.
The soil in my baskets is an experiment this year. I have read that widespread use of peat moss is not environmentally sustainable, so I am trying to find alternatives for turning organic garden soil into potting soil. This year I have tried mixing leaf mold, organic garden soil, and worm castings together in unscientific "but it looks right to me" proportions. I would guess the mix is about 1/3 leaf mold, 1/2 garden soil, and the remainder is vermicompost. I hope this mixture will give my plants what they need, especially in the way of water retention. Summers here get HOT!
Did I mention I sometimes forget to water my hanging baskets? I find drought-tolerant plants do better hanging in the North Carolina sun, since some of my baskets seem to need watering nearly every day. Hence my interest in the poppies.