The first key aspect is the ANNUAL LOW TEMPERATURE. Just because it gets hot in Death Valley, or Iowa, or Paris does not mean moringas will grow well there. This is because what limits moringas most severely is the yearly absolute (not mean) LOW temperature. Moringas do not tolerate frost. More importantly, they do not grow well in places that get below 10 degrees Celsius or so, and only then when such low temperatures are rare. 15 degrees as a general low is ideal. Here on the Jalisco coast, the lowest low is 17 degrees Celsius, perfect for moringas. These are occasional lows, at 3 am at the coldest time of year. 10 degree weather for days on end is as bad for moringas as a frost. Good AVERAGE DAILY temperature ranges are in the 20-35 degree range. The ANNUAL HIGH is important insofar as it is related to the average, but is not something to worry about too much. You won’t kill a moringa from high temperature, and it won’t even drop its leaves if there is water in the soil. In any case, tropical areas have more moderate climates than deserts and other extreme places, so anywhere with the minimum that is high enough for a moringa will have absolute high temperatures that are also in the correct range.
As to RAINFALL, practically any tropical area that meets the temperature requirements will meet the minimum rainfall needs of moringa. The problem in the tropics is likely to be too much rainfall. Moringas do best in areas that receive less than 1.5 meters of rain per year and where the rain falls in one or two concentrated seasons during the year, not evenly all year round. The wet tropics, as in rainforest areas, places where things like cacao, mangosteen, tea, oil palms, or allspice grow well are usually to wet for moringas to grow satisfactorily. Moringas hate water puddled around their roots, or heavy, fine soil that keeps their roots from breathing. On the other hand, they love any sort of well drained, open soil that allows lots of pockets of air around the roots. Fast draining gravelly soil is perfect, and they will also do very well in sandy soils. However, they will do poorly even on the best soils if they remain waterlogged. For example, deep volcanic soils are often perfect for moringas, but if they are in a high rainfall area the plants will suffer anyway.
With regard to LATITUDE and ELEVATION, moringa is a tropical lowland plant. The happiest moringas are the ones growing near sea level to 500 meters above sea level or so. In some places, moringas will manage up to about 1000 meters (Tequesquitengo here in Mexico comes to mind), and will survive but won’t be as happy up to 1500 meters or so. Above 1500 meters is completely out of the question as far as serious moringa country goes. Remember that moringa is a tropical plant and these elevations apply to TROPICAL latitudes, between 23 north and south latitude or so. Moringas really don’t grow well outside of these latitudes and certainly not at higher elevations.
Yes Moringa oleifera will hang on in many marginal places, even sputtering out a flower and a fruit or two in places like southern California, the Mexican or Kenyan high plateaus, or the Canary islands. This is great; everyone who can should enjoy a moringa or two in their yard. But serious moringa cultivation, where a community, a family, or a farmer depends on it, needs a real dry tropical area: 10 degrees or so as an absolute annual minimum temperature, preferably 15; seasonal rainfall, 1.5 meters or less; open soil.
Below are some tables giving combinations of temperature and rainfall in areas where I have seen moringa growing well. These illustrate my points. Moringas like it warm, with very high low temperatures. The highs can be high, but the lows need to be high. Rainfall tends to be low, 1500 mm or often much less, and is highly seasonal, usually with 8 months or so of very dry weather. Moringa is a lowland plant, growing best below 500 m above sea level.
Work on the distribution of Moringa in Mexico is in collaboration with Dr. Leonardo Alvarado Cárdenas