The kale in the photo grew continuously for two years. (This photo was taken when I first planted this kale.) I haven’t added any compost or worm castings to the Mel’s Mix since the kale was first planted. I noticed in September that aphids were beginning to multiple on the leaves. Yesterday I ripped up and composted the kale; aphids were everywhere.
I also planted a new crop of kale in a different location. There are no aphids on those plants. Disease attacks weak plants. The freshly planted kale plants are growing in compost, worm castings, vermiculite and peat moss. In a raised bed the soil mixture needs to be added to each time there are new plantings. With SFGs we are not using chemicals to fertilize the crops.
When you pay more at the grocery store for organic crops there is a reason. We could have sprayed the infested kale, killed the aphids and then what remains are weak plants. In that case we would have been eating two things; plants lacking nutritional value and and the poison from the pesticides.
1 Square Foot at a Time 
I plant peas around perennials to boost the nutrition. I also overdress with compost and keep enriching the soil as I go. I plant hummingbird attractors around my plants because they eat aphids more than anything, and monoculture creates plagues of pests. Nice picture, makes me want to reach down and harvest!
Thank you for your comments. Great ideas that you have shared.