Manihot

( MAN - ee - hoat )

At-A-Glance Information

This genus produces trees, shrubs, and a few herbaceous plants native to the Americas, spanning a range from Arizona, United States down through Argentina and Uruguay in South America. The best-known member of the genus is the widely cultivated crop species Manihot esculenta, commonly called Cassava. Grow these for a tropical accent in shady mixed beds and borders or as crop plants in edible gardens. Take care when planting Manihot in the landscape, as plant parts are toxic if ingested by humans or pets; in order for roots to be edible, they must be cooked.

Manihot Species and Varietals

The genus Manihot is a member of the Milkspurge plant family, Euphorbiaceae, and includes about 117 species. Both the scientific genus name as well as the common name 'Manioc' are both derived from the Guarani (Tupi) name mandioca or manioca for the plant. The best growing zones for Manihot plants are USDA zones 8-11. To find your zone, click here: Zone Map.

Manihot esculenta (Cassava, Manioc, Yuca, Tapioca, Bitter Cassava, Mandioca)
This species is native to South America, and is a perennial plant that is often cultivated as an annual crop for its tuberous root system. Cassava root is typically boiled and processed to make Tapioca. There are variegated cultivars of this species that make great garden ornamentals, as well. Plants in this species reach up to between 6 and 10 feet tall when mature. In tropical environments, they can reach up to 15 feet. Evergreen in USDA zones 10-12; these plants need 8-9 months of warm weather (temperatures above 60 degrees Fahrenheit to grow well.

Manihot grahamii (Hardy Tapioca, Graham's Cassava, Graham's Manioc)
This is a fast-growing species that reaches up to 10 feet tall when mature, and forms a treelet with large, green palmate leaves. Flowers are bell-shaped and pale green, blooming in summertime. This species is native to South America, and will die back to the ground each winter in most climates. Will re-seed if allowed to mature and conditions are right. This species is considered invasive in warm temperate and subtropical regions, including the southeastern United States, Italy, and New Zealand.

Caring for Manihot

Take care when planting Manihot in the landscape, as plant parts are toxic if ingested by humans or pets; in order for roots to be edible, they must be cooked. Manihot, or Cassava, plants are typically either grown from seed or purchased as starts from a reputable nursery. Cassava plants cannot be propagated using roots purchased from a grocery store. They are simply underground storage organs, and lack the necessary buds and nodes to sprout new growth when planted. Space plants about 3.5 feet apart for best coverage and airflow. Choose a space in the landscape that receives full sun; ideally, they should get between 6 and 8 hours of sun each day for best harvests. In warmer climates, late afternoon sun can cause leaves to sunburn; provide some shelter from rays in these situations when temperatures are at their peak (typically between 2 and 3 PM). Ensure that the soil profile is deep in the area you will be planting Manihot, as they have large root systems and prefer not to have hardpan layers or large rocks in their root zone. Soil should be well-draining, fertile, and have a pH of between 5.5 and 8.0 (acidic to slightly alkaline). If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Apply a layer of mulch around the planting area to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water new plantings regularly as they establish a strong root system in their new home. At maturity, Manihot plants appreciate consistent moisture, but not boggy conditions, which will cause issues with root rot.

Fertilize yearly in early springtime with an application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. As long as soil is rich in nutrients and organic matter, this feeding will be enough to carry the plant through the growing season. Prune regularly, removing leaves every so often to encourage a shorter, bushier form. This will also prevent the plant from becoming leggy, especially if it is grown in more of a shaded location. Crop plants grown as annuals are typically pulled at the end of the growing season in late summer or fall for harvesting roots. Manihot can stay in the ground and handle mild winter weather, but will not survive freezing temperatures. If you live in a cooler climate, you can save cuttings to plant the following season. Take a few 8-12 inch stem cuttings and pot them in sand with the bud side up. Keep the pot in a frost-free location and water every two weeks. Plant the cuttings out into the garden the next springtime after the last frost has passed.

Growing Manihot in Containers
These plants are perfect for adding tropical vibes to patios, walkways, and balconies when grown in containers. Container growing Manihot is recommended for gardeners in northern climates, as containers can be easily moved to a more sheltered location for overwintering. Most species of Manihot will not grow well in containers; though there are some more compact (to 2-3 feet tall at maturity), typically variegated types that can be grown successfully indoors. Ensure that the pot is large enough to accommodate the plant; they will need a pot that is at least a foot in diameter that has adequate drainage holes to allow excess water to escape. Keeping the pot on a tray filled with pebbles can create a more humid environment for these subtropical plants. Use a well-draining potting soil amended with plenty of organic material. Apply a layer of mulch to the top of the pot after planting to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water on a regular basis, keeping the soil moist. As a general rule of thumb, irrigate whenever the top inch or two of soil feels dry to the touch. As plants increase in size, they will need to be either divided or potted up.

Harvesting Manihot
Take care when planting Manihot in the landscape, as plant parts are toxic if ingested by humans or pets; in order for roots to be edible, they must be cooked.
Manihot roots are the source of Cassava and Tapioca products. There are sweet and bitter Cassava varieties; make sure when choosing a variety to grow for root cultivation that it is a sweet variety with low HCN (Hydrocyanic glucoside) content. These plants will be ready to be harvested at any time after the roots become established (as early as eight months after planting). The harvest time depends on the desired size of the roots; the longer they stay in the ground, the larger they will get. However, very big roots tend to become woody and inedible (this typically happens if they are grown for more than one season). The best indicator to harvest is at the end of the first growing season when the leaves begin to fall from the plant. To bring the root out of the ground, gently work your way around the outside of the root system, lifting it gently out of the soil. Once the entire plant is up, cut off any above-ground foliage using a sharp, clean knife.

Handle Cassava root gently, as it bruises easily. These roots have a short shelf life, typically only one or two weeks. Keep roots in a cool, dark, dry place to extend freshness as long as possible. To store it for extended periods of time, peel the root and cut it into pieces. These pieces can then be frozen and used at a later date. Peeled Cassava root can also be stored in water in an airtight container for up to a week if water is changed out daily. Cassava must be cooked to be edible; never eat raw Cassava roots. They are typically boiled, roasted, or turned into flour. They are also used to make the popular dessert Tapioca.

Disclaimer: Information contained on this website is strictly and categorically intended as a reference to be used in conjunction with experts in your area. Foraging and consumption of plant parts should never begin without the guidance and approval of a local plant specialist. The providers of this website accept no liability for the use or misuse of information contained in this website.

Propagation

Manihot, or Cassava, can be propagated by cutting or seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant, especially if you are propagating a hybrid cultivar. To propagate your Cassava plant, follow the instructions below:

Propagating Manihot by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
Harvest your seeds. The seed heads on plants are pretty easy to spot, they're left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will continue to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
Get your container prepared. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 2-6 weeks from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 65 and 72 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.

Propagating Manihot by Cutting

Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. A good substrate for propagation of cuttings is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
In early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 3-4 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new plant.

Manihot plants produce woody capsules that emerge green and smooth and mature to brown and dry. They explode when fully ripe to disperse seeds.

Manihot seed pods contain between 1 and 3 seeds each. Seeds are small, hard, and oblong, often with a mottled brown, grey, or black patterned seed coat.

Problems and Pests

Certain species of Manihot are considered invasive in some regions; see the species descriptions above for more information. Check with local authorities before planting. Manihot, or Cassava, plants are susceptible to developing issues with the following pests and diseases in the landscape: