Know your site
Getting to know the environment where you live is the best way to begin the process of growing food. Knowing about your soil, rainfall, elevation, wind direction, and other environmental conditions will help determine what to plant and what might need to be done to improve conditions for plants and animals.
Soil
Soils vary tremendously across the island, from sandy clays to coarse soil in lava rock. A soil test can help determine the nutrients available in your soil. The USDA also has detailed soils maps that can help determine your soil type.
Rainfall
Precipitation ranges from almost none to over 200 inches (5,000 mm) per year on Hawai‘i Island. Rainfall maps based on historical data can give you a good average value for your region, although actual rainfall can vary widely from year to year.
Elevation
Average temperature varies with elevation above sea level. In general, the higher the elevation, the cooler the average temperatures are.
Aspect and terrain
Aspect is the direction a slope faces (e.g., south, west, etc) and partly determines the amount of sunlight exposure on a site. Knowing the terrain features, such as degree of slope, peaks and valleys, and unusual land forms, such as lava tubes, will help determine the most advantageous areas to plant different crops.
Wind direction
The prevailing wind direction, particularly on the windward side of the island will help determine where windbreaks should be planted.
History
The history of the land includes native fauna and flora from the area, as well as human impacts and cultivation of the land.
Neighboring land
Neighboring plantings are good indicators as to what grows well, and what does not grow well in a certain area. Neighboring lands can also have a big influence, for example, in animal intrusion, rainfall runoff, and chemicals.
A survey of all environmental factors is the foundation for any sustainable farm design.
Craig Elevitch is director of Hawai'i Homegrown Food Network and an educator in agroforestry. His books include Agroforestry Guides for Pacific Islands (2000), The Overstory Book: Cultivating Connections with Trees (2004), Traditional Trees of Pacific Islands: Their Culture, Environment, and Use (2006), and Specialty Crops of Pacific Islands (2011) all of which promote diverse agricultural systems that produce abundant food.