Monday, January 5, 2015

Cacoa, Macadamia Nut and Coffee Trees - Climate Limitations





The cacao tree evolved as an understory shade tree in tropical rainforest areas. For commercial production, cacao is best adapted for hot, humid tropical areas with evenly distributed rainfall. This would mean year-round temperatures at, or above 68°F and no freezing temperatures.

For individual trees around the home, these limitations can be stretched.
Optimum temperatures range from 65 to 90°F. Temperatures below 50°F may damage or kill the plant; defoliation and dieback will occur between 40-46°F.  Most importantly, flowering and thus fruiting only occurs when temperatures are at or above 68°F. Temperatures in excess of 90°F  may also limit plant growth. As a reference the warm subtropical climate in South Florida is very marginal for growing cacao.

Cacao is a shade plant and grows best with about 25% shade.  It is often planted with other commercial crops that protect it. In some regions it is grown in full sun, although shade is used during establishment.  For homeowners it can be planted under the canopies of tall overhanging trees or next to buildings or structures. Cacao does not tolerate windy conditions and should be planted only in wind-protected areas.



On the other hand, macadamia nut trees can withstand colder temperatures than cacao. Although they are adapted to warm, subtropical conditions, mature trees can withstand winter temperatures as low as 25-26°F for short periods with minor foliar damage. Young trees, however, are killed by temperatures near freezing. Temperatures below 28°F will cause damage to flowers and young fruit thus reducing production. In the tropics, macadamias are better adapted to medium elevations of 2100 to 3600 feet.  In Hawaii, commercial macadamia trees are not planted above 2500 feet.



                                                                                        Forest and Kim Starr
The optimum growing conditions for coffee include high humidity, protection from wind and temperatures from 59 to 75°F. Coffee plants are damaged or killed by freezing temperatures, while constant temperatures at or below 41°F may cause leaf drop and tree decline.

In the tropics or the warm subtropics, coffee is grown at high altitudes up to 3,500 feet; temperatures there are moderate and never freezing. In a few places in Kenya and Columbia, coffee is grown at elevations as high as 7,000 ft.