Perennial plants are an important factor in stabilising the environment. Their above-ground parts reduce wind erosion and the roots act as soil anchors. Edible perennials provide a greater variety in the diet, and usually provide food even in years with poor rains, where the annuals fail. They also often provide food during different periods of the year than the millet, which can be very helpful if the food reserves run low. They are less likely to be chopped down or uprooted when farmers obtain food from them.
Perennials have a positive effect on the annual crops as well.
By intercropping them, which means to cultivate them in the same fields, they can protect the annuals from desiccating winds. Eden has a field station where plant species are tested. Species that germinate reasonably well and that have good survivability rates are considered for introduction to farmers. The species are tested with varying sowing depths and seed treatments to find the methods that give the best results. When Eden started, local farmers removed perennials from their fields as they considered them to be in the way of their annual staple crop, millet.