Vegetable · Euphorbiaceae
Cassava
Manihot esculenta
A tough tropical root crop that rewards warm, well-drained ground and demands careful processing before it reaches the table.
Full sun
Every 7–14 days
59–95°F · 15–35°C
240–360 days
Overview
Cassava (Manihot esculenta) is a woody tropical shrub in the spurge family (Euphorbiaceae), grown for the starchy roots that make it a major staple across warm regions. Native to South America and cultivated there for thousands of years, it earns its place by storing energy underground where it stays available through difficult conditions. Plants reach 5 to 10 feet (1.5 to 3 m) tall with a spread of 3 to 6 feet (90 to 180 cm), growing at a moderate pace as a perennial.
Its standout trait is drought tolerance once established, and the reason is structural: the roots bank energy and the tubers keep in the ground, so the plant can ride out dry spells that would stall other crops. That same biology sets the management rules. Give it full sun for the best root fill, since more direct light drives more of the photosynthesis that packs starch into the tubers, and keep the soil loose so the roots have room to swell.
The plant carries a serious caveat that shapes everything about handling it. Every part contains cyanogenic glycosides that release hydrogen cyanide when the tissue is damaged, which means raw or poorly processed cassava is genuinely poisonous. The flip side is well understood: peeling, grating or soaking, and thorough cooking drive off the cyanide and make it safe, which is exactly how it feeds millions of people every day.
Care
The short version: Plant woody stem cuttings in full sun on well-drained sandy loam at a pH of 5.5 to 6.5, after frost has passed and the soil is warm. Water young plants to establish them, then back off, since cassava is highly drought-tolerant once settled and waterlogging rots the roots. Feed a balanced NPK with adequate potassium at planting, hold it between 59°F to 95°F (15°C to 35°C), and harvest the roots 8 to 18 months later before any frost. Never eat any part raw.
Light
Give cassava full sun; it tolerates partial shade but the trade-off is real. More direct light means more photosynthesis, and that extra energy is what fills out the roots, so shade means thinner tubers and a smaller harvest.
Water
Water young plants enough to establish them, then cut back, because once settled cassava is highly drought-tolerant and stores its own reserves in the roots. In dry spells, watering every 7 to 14 days is plenty; let the top 3cm dry between waterings. Avoid waterlogged soil, which starves the roots of oxygen, causes rot, and reduces tuber quality.
Soil
Use a well-drained sandy loam at a pH of 5.5 to 6.5. The looseness matters mechanically: open ground lets the roots expand and swell into proper tubers, while drainage keeps water from sitting around them and triggering rot.
Temperature
Hold cassava in the range of 59°F to 95°F (15°C to 35°C). It is frost-tender, with no tolerance for ice in its tissue, so a cold night blackens the foliage. Keep the whole growing window inside the warm season.
Humidity
Average humidity of 40% to 70% suits cassava well. It copes with drier air better than most tropicals, a reflection of its drought-adapted biology, so you rarely need to take any special steps to raise moisture around it.
Feeding
Cassava is not a hungry crop. A single application of balanced NPK with adequate potassium at planting covers it, with the potassium specifically supporting root development so the energy goes into building tubers rather than excess leafy top growth.
Pruning
Keep pruning minimal. Remove lower lateral shoots to focus energy into the main growth and the roots, and cut back any frost-killed or damaged stems. At season's end, save healthy stems as cuttings for next year's planting material.
Repotting
not typically container-grown
Size & spacing
Plan for a shrub of 5 to 10 feet (1.5 to 3 m) tall and 3 to 6 feet (90 to 180 cm) wide. It grows at a moderate rate as a perennial and is outdoor only, not container-grown, so give each plant room to reach full spread.
When to plant
Cassava is a one-season warm crop in temperate gardens because it is frost-tender at both ends. Wait until frost danger has passed and the soil has warmed before planting stakes, let the tubers bulk over a long stretch, and lift the roots before the first frost of fall can kill the top and waste the stored starch.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Plant woody stem cuttings (stakes) after all danger of frost has passed and soil is warm.
- Harvest: Harvest roots 8-18 months after planting, once tubers have bulked.
Hardiness
USDA hardiness zones: 9–11
Temperature: down to -7°C
Troubleshooting
Most cassava trouble comes down to three causes: a virus carried by whiteflies and infected cuttings, root rot from soil that holds too much water, and cold injury in a plant with no frost tolerance. Reading the symptom against the mechanism below tells you whether to start clean, fix the drainage, or simply harvest ahead of the cold.
Mottled, twisted leaves point to cassava mosaic virus
When foliage turns a patchy yellow-green and leaves warp and stay small, the plant is almost always carrying cassava mosaic virus. There is no cure once a plant is infected, because the virus moves systemically through its tissue. It spreads two ways: whiteflies feeding on a sick plant and then a healthy one, and cuttings taken from stems that already harbor it. Pull infected plants and destroy them rather than composting them on site, since they remain a reservoir for the whiteflies. The reliable fix is to begin clean with certified virus-free stakes and keep whitefly numbers down so the cycle cannot restart.
Fix:
- Remove and destroy infected plants
- Use virus-free planting material
- Control whitefly vectors
Blackened, collapsed growth follows a cold night
Cassava is frost-tender, so foliage and stems that blacken and fall over after a chilly night are showing classic cold injury. The plant evolved in warm tropics and has no defense against ice forming in its tissue, which is why a single night near or below freezing can flatten the canopy. Harvest the roots before frost is forecast so the stored starch is not lost to a dead top, and protect or relocate plants where that is practical. In all but the warmest zones, treat cassava as a single warm-season crop, timing planting and harvest to fall entirely within the frost-free window.
Fix:
- Harvest roots before frost
- Protect or relocate if possible
Soft, foul tubers and wilting trace back to root rot
Soft, discolored roots that smell of decay, paired with a wilting top, are the signature of root rot driven by standing water around the tubers. The mechanism is straightforward: saturated soil starves the roots of oxygen, which kills tissue and lets decay organisms take hold, so the energy stored in the tuber is lost. Dig and inspect a root to confirm the soft, foul-smelling collapse and check whether water is pooling. Plant on ridges or a well-drained site to keep the swelling roots above wet ground, ease off watering, and lift the roots promptly once they have bulked so they are not sitting in cold, wet soil any longer than needed.
Fix:
- Improve drainage
- Avoid overwatering
- Harvest promptly once mature
Toxicity
This is the part of cassava that demands respect. The whole plant holds cyanogenic glycosides (linamarin and lotaustralin) that release hydrogen cyanide the moment tissue is crushed or chewed, so raw roots and leaves are dangerous to people and animals alike. The toxin is removed by proper processing, but until then keep raw plant material away from children and pets.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Severe
A cat that chews raw cassava can release hydrogen cyanide internally, and you may see heavy drooling, vomiting, and labored breathing. As the cyanide blocks the cells from using oxygen, watch for dilated pupils, weakness, convulsions, and collapse. Treat any of these as an emergency and get veterinary care at once.
Dogs Severe
In dogs the early signs of cyanide release are drooling, vomiting, and breathing trouble, since the toxin interferes with oxygen use at the cellular level. Staggering and seizures can follow as the nervous system is starved of oxygen. Do not wait for the picture to worsen; a dog showing these symptoms needs a vet immediately.
Horses Toxic
Horses that ingest raw cassava tissue may show fast, distressed breathing and trembling as the body fights to compensate for blocked oxygen use. Stumbling follows as muscles and nerves fail, and a large dose can be fatal. Any sign of cyanide exposure in a horse warrants urgent veterinary attention.
Rabbits Toxic
Because their small bodies handle cyanide poorly, rabbits are at serious risk from even modest amounts of raw cassava. Expect weakness, gasping, and twitching as the toxin takes hold quickly in a small animal. Keep all raw plant material well out of reach and seek help fast if exposure is suspected.
Livestock Severe
Cattle, goats, and sheep that graze on raw cassava can absorb enough cyanide to show rapid breathing, drooling, and staggering. As oxygen use is blocked throughout the body, muscle tremors, convulsions, and collapse can follow quickly. Suspected poisoning in any of these animals is a veterinary emergency.
Birds Toxic
Poultry and pet birds react to cyanide with labored breathing and sudden weakness, and their small size makes even a modest amount serious. The toxin works fast in a small body, so there is little margin for delay. Remove access to raw cassava and contact an avian vet right away.
People Caution
Cassava feeds millions safely, but only after peeling, grating or soaking, and thorough cooking drive off the cyanide. Raw or half-processed roots and leaves release hydrogen cyanide that causes vomiting and dizziness, and steady reliance on under-processed cassava can lead to konzo, a lasting paralysis. No part of the plant should ever be eaten raw.
Proper processing (peeling, grating/soaking, and thorough cooking) drives off the cyanide and renders cassava safe to eat; the raw plant and unprocessed roots/leaves are dangerous. Keep raw plant material away from children and animals.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
Cassava splits into two practical groups defined by where the cyanide-forming compounds sit and how much of them there are. The distinction matters because it sets how hard you must process the root before it is safe, so know which type you are growing before you cook.
Sweet cassava
This group carries fewer cyanide-forming compounds, and most of what it does hold sits in the peel rather than the flesh. That does not make it safe to eat as is; peeling and cooking are still required before any of it reaches the plate.
Bitter cassava
Here the cyanide-forming compounds run throughout the root, not just the skin, so the flesh itself is dangerous until treated. Safe use demands heavy processing: grating, soaking, fermenting, and cooking to drive the cyanide out.
How to propagate
Cassava is propagated from woody stem cuttings rather than tubers or seed, which keeps each new plant true to its parent and gets growth started fast. The method is easy and well suited to home growers as long as you take sound stakes and plant them into warm soil.
Stem cuttingsEasy
Plant mature woody stem cuttings (stakes) at the start of the warm season after frost danger has passed. · 2 to 4 weeks for sprouting and rooting
Cassava is grown from stem cuttings called stakes, not from tubers or seed, because the woody stem reliably carries dormant buds that break into new shoots. Take stakes 20 to 30 cm long from mature, healthy stems, plant them as the warm season begins, and expect new shoots and roots in about 2 to 4 weeks.
Myths
A quick boil makes any cassava safe to eat.
A brief boil leaves far too much cyanide behind, especially in bitter types. Those need peeling, grating, soaking, and a long cook to release the bound cyanide, and relying on under-processed roots over time leads to cyanide poisoning and konzo paralysis.
Only the roots of cassava are poisonous.
The leaves carry the same cyanide-forming compounds as the roots, so the danger is not confined below ground. Both the roots and the leaves must be properly processed before any person or animal can safely eat them.