My sister recently went on a permaculture course (highly reommended!) so she shared part of what she learnt re: balance in a garden between plants and wildlife!
So the aphids need ladybirds to keep them under control. She suggested to plant dill next to any plants that encourage aphids as ladybirds are enticed by the dill! also to provide a shelter/ area for the ladybirds so they can nest overwinter int he garden as well