Cassava can be grown almost anywhere in the tropics, but is very frost-sensitive. Cassava can survive in dry conditions for a very long period of time and still go on to produce a good crop. It can be an extremely heavy yielder.
Cassava is uniquely flexible because it can remain in the soil in a living condition for a very long period of time and can then still be used as food. However, once harvested, it has a very poor storage life; it begins to deteriorate about a week after it is harvested, so it needs to be eaten or processed very quickly.
Some cassava roots contain significant amounts of hydrocyanic acid. These are called bitter cassava. Cassava roots with relatively small amounts of hydrocyanic acid are considered not harmful and are referred to as sweet cassava.
A common way to cook sweet cassava is to peel and wash the roots, cut them into pieces and then boil them in water. Cassava can also be used to make flour or starch, a good use for the bitter varieties as they tend to be more pest and mosaic virus resistant than the sweet varieties.
The leaves are also eaten as a vegetable in some countries but care must be taken to cook them properly because they contain cyanide precursors.
Cassava is propagated from a piece of the stem about a foot long and fairly thick. The cassava stick is either buried in the soil or placed in the soil at an angle, with about a third above the level of the soil. The stem is resilient and keeps well. Even under relatively poor conditions, the stem will eventually produce roots, and some of those roots will produce cassava.
Cassava takes a long time to mature. A few varieties can be harvested in eight months, but harvest after a year is not considered excessive. Some varieties are harvested at a full year and a half.
A common way to cook sweet cassava is to peel and wash the roots, cut them into pieces and then boil them in water.
To make flour the roots are fermented before being dried and then ground to make flour used for bread and fufu. To make starch, fermented roots are grated, mixed with water, strained and then left for the starch to settle out. The starch can then be used to make tapioca. In one method, moist starch is dried over a fire on top of a metal sheet; as this drying occurs, the small grains of starch tend to accumulate and stick to each other, making little balls of tapioca. In another method, moist starch is rolled out, cut into pieces and rolled into tapioca balls.
ECHO Technical Note #81