How to Grow and Care for Cassava

Cassava is a woody shrub that grows in a warm, tropical or subtropical climate. The large, green leaves add some ornamental interest to a garden landscape but cassava is primarily grown to harvest the leaves and tubers. The tuberous root is a popular starchy carbohydrate food source in South Africa and Southeast Asia. For a strictly ornamental plant, choose the variegated variety; it has attractive palmate leaves with creamy-yellow centers and bright red stems.

In its uncooked state, the roots of cassava are toxic to humans and pets.

How to Plant Cassava

When to Plant

Plant cassava in the spring after there is no more danger of frost. The plant needs at least eight months of warm weather to produce a crop.

Selecting a Planting Site

Give cassava a location with full sun and deep, fertile, and moist soil. Cassava is a large plant so make sure it has ample room to grow.

Spacing, Depth, and Support

Cassava cuttings should be spaced 20 to 30 inches apart and planted 2 to 8 inches deep, depending on their size. Placing the cuttings upright (vertically) is preferred over horizontal planting because it can help prevent root rot.

Cassava does not require any support.

Cassava Plant Care

Light

Although cassava plants produce their best harvest if they get extended exposure to sunlight, intense direct sunlight may cause leaf burn. In these instances, a partial shade environment would be better.

Soil

Cassava is highly tolerant of a wide range of soils and pH levels, providing it is well-drained. For best results, however, a sandy, loamy soil works well.

Water

Part of the cassava's appeal is its ability to tolerate periods of drought and also heavy summer rains. Some cultivars, however, are more drought-tolerant than others, so you should do your research before planting. Standing water can cause root rot, so if you live in a rainy region, the soil needs to have excellent drainage.

Temperature and Humidity

To ensure a good crop year-round, cassava needs a frost-free climate. The plants don't tend to do well in temperatures below 60 or above 85 degrees F.

Fertilizer

The fertilization requirements of cassava are similar to those of the sweet potato. The fertilizer should be higher in potassium to prevent elongated, straggly roots. If you intend to harvest the leaves, a fertilizer with more nitrogen will work better.

Sweet vs. Bitter Cassava

There are sweet and bitter cassava varieties. Bitter varieties contain a higher amount of hydrocyanic glucosides (HCN), which is toxic but destroyed during cooking.

The amount of HCN determines whether it is bitter or sweet. Low HCN means sweetness. Plants are identified as bitter or sweet by their taste and smell. When planting cassava for consumption, make sure it is a sweet variety with low HCN content.

Harvesting Cassava

Cassava is ready to be harvested any time after the roots are established, which can be as early as eight months after planting. The harvest time depends on how large you want the roots to be. However, the core of very big roots that have grown for longer than one season tends to become woody and inedible. For that reason, cassava roots should be harvested at the end of the growing season when the leaves begin to turn yellow and drop. If you are growing cassava as a perennial, don’t pull the entire plant but only as much as you consume and leave the rest in the ground. The plant will regrow after its winter dormancy, which typically lasts two to three months.

How to Grow Cassava in Pots

Only the variegated form of cassava, Manihot esculenta 'Variegata', is suitable for container growing. because it is much smaller than the species, reaching a height of 2.5 to 3 feet. Use a large container, at least 1 foot in diameter, and fill it with well-draining potting mix. Make sure the container has large drainage holes. Potted cassava needs more frequent watering and fertilization than cassava in the garden.

Repot the plant to a larger container with fresh potting mix when the roots have filled the container.

Pruning

Regularly harvesting the leaves automatically takes care of the pruning and encourages shorter, more bushy growth. If you don’t use the foliage, the plant benefits from light pruning to prevent it from becoming leggy.

Propagating Cassava

Cassava is commonly propagated from cuttings, not seeds. 

1. In the spring, after all danger of frost has passed, take hardwood stem cuttings about 1 foot long. Remove all the leaves. 
2. Dig a hole deep enough to place the cutting in the soil in an upright position with one node (the point where a leaf was attached to the stem) above the soil level. 
3. Water it well and keep it moist until the cutting is established, at least for the first two months.

Overwintering

If cassava is grown in a frost-free zone, it does not need winter protection. Placing a 3-inch layer of mulch around the base of the plant helps to protect the roots from the winter cold.

Common Pests and Plant Diseases

Cassava is not often affected by serious diseases or pests. The plants may get mosaic virus and bacterial diseases. Potential pests include locusts, beetles, and aphids.