Diversity is the state or fact of being different, unlikeness, or having variation or dissimilarity. So why would this be a good thing and how does it improve or enhance of gardens, flower beds, and food production? When we look at nature, we see what we want to see. By that I mean if you are looking at the beauty of nature with flowers, you see flowers. And the same holds true for forests, grasslands, and stream beds. But if we look deeply into nature, we see that immense variation and diversity play a key role in the organization and structure within nature. Diversity by itself has nothing to do with companion planting, it states merely that it is composed of varying constituents. But take the varying constituents and design them based on what we know as designers and gardeners, then we create a richness of species with a moderate level of stress and competition in the plant system. Then as nature adjusts the plants interaction between species, nature will adjust our gardens based on the results and interactions between the varied species of plants, the birds and other wildlife. They provide valuable information as to the total sum of the plants we have selected.
To create a diverse organization of plants, we have to understand the strengths and weaknesses of each plant that we intend to use in our final design. If we want to repel insects then we would consider adding rue, tansy, borage, alliums, garlic, chives, or oregano to name a few. If we wanted to increase nitrogen within the soil we would include comfrey, horsetail, alfalfa, Siberian pea, cowpea, or scarlet runner beans. If we wanted to increase potassium then we would include borage, if we wanted to increase magnesium we would include beets. Look at the locations that are suggested for the plants to determine if they like full sun, part sun, or part shade. Do they like dry soil, moist soil, or wet soil? With the pieces of information gathered we can start to place the plants to obtain the most from each plant, but also to help the individual plants support each other much like a small community. If we look at monoculture planting or planting of one species only, there is a much greater risk of failure due to insects, weather related issues, or disease. Polyculture or planting multiple species creates a much more diverse plant guild that mimics nature in the truest form, while also creating a more permanent ecosystem of plants while increasing the output and decreasing human intervention and maintenance.