Some vegetables benefit from full sun while others thrive in the shade provided by nearby plants. Other vegetables might boost the soil with nitrogen while a neighbouring row depends on nitrogen. This [guide] (http://en.wikipedia.org/wiki/List_of_companion_plants) and this robust [chart] (http://farmon.com/media/92274/poster_gdn_com_plant.pdf) are two references for improving the design, and as a result, the health and vibrancy of your garden. Companion planting is also another method to maximize space and have a better yield from a small space. For example, carrots, with the majority of their goodness taking place underground, is great right next to lettuce or spinach which is an above ground crop.