Companion planting involves growing multiple crops in close proximity that provide benefits to each other such as pest control, pollination or nutrient exchange. It has been used for centuries in gardens and agriculture as an environmentally friendly technique. Some key benefits of companion planting include attracting beneficial insects for pest control, fixing nitrogen in the soil, providing shelter from wind and pest disruption through diversifying crop placement. Examples given are planting marigolds with crops to deter pests, and the traditional "Three Sisters" method of growing corn, beans and squash together. Recent studies also show companion planting to be an effective method for disrupting pest host-finding and increasing yields.