Growing Cassava in Ghana: Planting to Harvest

Cassava is planted from sticks, not seed

Cassava is one of the few crops here that you plant from a stick. A cutting from a mature stem takes root, sprouts, and grows into a plant that will carry tubers for nine to twelve months. There is no seed bag and no germination test in the usual sense, which makes the choice of planting material the single most important decision on the farm.

Take cuttings from healthy stems of a mature plant, usually from a crop of about nine to twelve months. Cut them into pieces about 25 to 30 centimetres long, each with several healthy nodes. Discard the thin top part and the very woody base, and keep the middle section where the stem is firm and green inside. Get the cuttings into the ground within the day you cut them, or keep them shaded and moist for no more than a day or two. Dried-out cuttings fail to root.

In the field, the cutting goes into the ridge or mound at an angle or upright, with at least two or three nodes buried. A cutting planted upside down can still root, but it sprouts more slowly and the stand is patchy. Replace any cutting that fails within the first few weeks, while the young shoots can still catch up.

Where cassava fits in Ghana's zones

Cassava grows best in the forest, the transition belt and the coastal savanna, where the rains are reliable for most of the year. It is drought tolerant once established, but a 12-month crop asks for a long, steady season. In the north, from Tamale up to Wa and Bolgatanga, the rains are shorter and the dry season is harsh, so the crop either runs into the dry months or needs to be planted to finish earlier. Northern growers often choose shorter-duration types and accept a smaller harvest.

The forest and transition zones have the best record for cassava, with rains that fill the roots and a market for fresh roots and processed products close by. The coast has its own challenges, including sandy soils that are low in nutrients and disease pressure that can build quickly on the same land.

Before you plant, check the length of your rains against the duration of your variety. A variety that needs twelve months in a district with eight months of rain is a poor choice.

Varieties: bitter, sweet and the processing market

Choose cassava by its duration, its disease tolerance and its use. The Crops Research Institute at Kumasi releases cassava varieties for Ghanaian conditions, and recent releases have included Afisiafi, Bankyehemaa and Okyeame. Check the current recommended list with CRI and your district agric officer, because new lines are released from time to time. A variety that is tolerant to cassava mosaic disease is worth more than one that yields a little more on a clean season.

Varieties are often described as bitter or sweet. Bitter types contain more cyanogenic compounds in the root, and they must be processed before they are eaten. Sweet types contain less, and they are sometimes eaten boiled or roasted. Both need proper cooking, and both can be processed into gari, fufu flour, starch or chips. Ask buyers what they want, because a bitter variety that gives high-quality gari can fetch a better return than a sweet one that does not process well.

Do not assume a variety that does well in one zone will do the same in another. Ask for the performance record in your district, and plant a small trial block of two or three varieties before you commit a large area. A trial gives you real information about yield, root quality and disease in your own field.

Replacing the variety you grew last time

Many farmers keep planting the same variety from their own field for years. Over time it picks up virus and loses vigour. Renew your planting material from a trusted source every few seasons, and keep a record of where each cutting came from.

Clean cuttings and the diseases that travel with them

Two virus diseases matter most for Ghanaian cassava. Cassava mosaic disease, known as CMD, shows as mottled, distorted leaves and stunted plants, and it is spread by whiteflies and carried in the cuttings. Cassava brown streak disease, known as CBSD, causes brown streaks on the stems and brown, rotted patches inside the roots, and it spreads in the same way. Both can cut the harvest sharply, and CBSD can spoil roots that look fine on the outside.

The defence is clean planting material and tolerant varieties. Take cuttings only from fields you have walked and inspected, and do not use stems from a plant with leaf distortion, yellowing or brown streaks on the cut. Remove diseased plants from the field as soon as you see them, and keep infected material away from the cutting store. Plant tolerant varieties where the disease is known, and check the current list with CRI.

Cassava mealybugs and green mites are the other pests to watch. Mealybugs cluster on the tips and the undersides of leaves, and they can stunt the crop in a dry spell. Biological control is the long-term answer, and research institutes have released natural enemies for some of these pests. Ask CRI or your extension officer whether a biocontrol programme is running in your area before you consider any spray.

1. Inspect the source field before you take any cuttings.
2. Reject stems with mosaic, distortion or brown streaks.
3. Get cuttings into the ground the day they are cut.
4. Pull infected plants from the new field as they appear.

Land, ridges and the planting date

Cassava likes a deep, loose soil that the roots can enter. Clear the land, plough or hoe it to a good depth, and build ridges or mounds. Ridges work well on flat, well-drained land. Mounds suit drier sites and sandy soils where water drains quickly. Low spots that hold water after storms are not suitable, because cassava roots rot when they sit wet for long.

Plant with the start of the main rains, when the soil is wet enough to hold a cutting and the season ahead is reliable. In the forest and transition zones that is usually in March to April, and in some districts a second planting is made in the later rains. In the north the window is shorter and set by the first steady rains. Confirm the dates locally with your district agric officer.

A common spacing for cassava is about one metre between plants and one metre between rows. Wider spacing gives the plants more room and makes weeding easier, but it can leave ground open to weeds early on. Adjust to suit your intercrop and your equipment, and keep the rows straight so the weeding is quick.

Weeding and feeding the young crop

The first three to four months are the critical period for cassava. Weeds that establish in this window compete for light, water and nutrients, and they cut the yield more than a late pest usually does. A cassava field that is weeded at three to four weeks and again at eight to ten weeks normally closes its canopy and shades out most of the later weeds.

Hoe between the rows and hand-weed close to the plants, taking care not to damage the stems or the young roots. Do not leave weeds to grow tall between the rows, because they are harder to remove and they seed. Once the canopy closes, the weeding load falls sharply, and a single check later in the season is often enough.

Mulch is useful where you have crop residue. A layer of dry leaves or grass around the plants cuts weeds, holds moisture and keeps the soil cooler in the dry spell. Keep the mulch clear of the stems to avoid rot.

Cassava takes a lot of potassium from the soil, and it removes nutrients steadily as the roots fill. Many fields in the forest and coastal zones are low in potassium after a few seasons of cassava without any replacement. A soil test shows what is missing, and it is the right starting point before you buy any fertiliser.

Manure is a reliable partner for cassava. Well-rotted manure, including dried poultry manure applied at a measured rate, improves the soil structure and supplies nitrogen and phosphorus. Read our poultry manure fertiliser guide before you apply it, because the strength of dried manure varies from one shed to another. Apply it on the ridge before planting, and avoid putting fresh manure in direct contact with the cuttings.

Where the soil test shows a shortage of potassium or phosphorus, follow the blend and rate your extension officer recommends. Split applications are sensible on sandy soil, because the nutrients can leach out in heavy rain before the roots reach them. Keep the fertiliser off the stems, and water it in lightly if the field is dry.

Intercropping with maize, cowpea and groundnut

Cassava is often grown with other crops in its first year, and intercropping can make good use of the land while the roots develop. The right partner depends on the zone, the variety and how much shade the cassava will carry in its early months. Early-maturing companions harvest before they compete with the cassava for light, and slower crops are best planted on the outer rows or in a separate block.

Maize is the usual first companion. It matures in about three to four months, and it gives a harvest early in the cassava's cycle. Cowpea and groundnut are useful because they fix nitrogen and cover the ground, which cuts weeds and feeds the soil. Plant the companion crop in its own rows, and leave the cassava room to grow.

Keep the companion crops in a clean rotation. Cassava after a legume is usually a better bet than cassava after cassava on the same ground. Our guides to cowpea and beans and groundnut cover their own needs in more detail.

Harvest at nine to twelve months, and move fast

Most improved cassava varieties are ready to dig between nine and twelve months after planting. Some farmers leave the bitter types longer to build up starch, and the field can carry on for a few extra months with care. The plant gives a clear sign when it is close to ready: the lower leaves yellow and fall, and the stems begin to change colour. Dig a test root from a few plants across the field to check the size and the quality of the root before you commit the whole block.

Lift the roots carefully with a fork or a hoe, working around the stem so the roots do not break. Broken roots deteriorate quickly. Carry the harvest to the processing point the same day if you can. Roots left in the sun or in a heap begin to spoil within a day or two, a process called post-harvest physiological deterioration, and the spoilage shows as blue-black streaks in the flesh. Process the roots quickly, or leave the field in the ground until you are ready to dig again.

Plan the harvest so that the roots go to market or to the processing shed without delay. A cassava field that is dug in the morning and processed by evening loses very little value. A field dug on a Friday and left until Monday loses a great deal.

1. Dig a test root from several plants before you start the block.
2. Lift the roots with care, and keep the tubers unbroken.
3. Carry the roots to processing the same day.
4. Process, peel or dry the roots within one or two days.

Cyanide, processing and food safety

Cassava roots hold cyanogenic compounds that are freed when the flesh is cut, crushed or chewed. The levels are higher in bitter types, but even sweet varieties need care. The compounds are reduced by peeling, grating, soaking, fermenting and drying, and the traditional processing methods used in Ghana are designed for exactly this. Gari, fufu flour and starch are all made using these steps. Eating raw or poorly processed roots is dangerous, and it is the reason the processing methods exist.

Peel the roots fully, because the peel carries more of the compounds than the flesh. Grate or chop the roots so that the cells break and the compounds can escape. Soak or ferment the pulp for the time your traditional method calls for, then press and dry it. Dry cassava products out of the sun and off the ground, and keep them dry until they are used. Cooking alone is not enough for bitter roots unless the processing has been done first.

Keep children and visitors away from the processing area when fresh roots are being handled, and warn family members not to eat raw roots from the field. If anyone develops symptoms after eating cassava, seek medical help straight away.

Cassava products and the poultry side

Cassava products can enter a poultry ration in limited amounts once they are dried and processed correctly. Dried chips and leaf meal are used in some rations, and peels can be included after drying, but each has a limit set by the level of cyanogenic compounds and by the rest of the mix. Our cassava in poultry feed guide covers the inclusion rates and the risks in more detail, and the cassava leaf meal guide covers the leaves separately.

The safest rule for a home flock is to rely on a commercial starter or grower ration for the early weeks, and to introduce any cassava product only after you have dried, checked and tested it. Never feed fresh peels, raw roots or wet pulp to birds. Keep the dried products in a clean, dry store, and check them for mould before each use.

If you already keep birds on a cassava farm, the peels and the leaves are a free resource that would otherwise go to waste. Use them carefully, and treat the poultry side as an add-on to the crop rather than a replacement for a sound ration. For a starter plan, begin with our day-old chicks page.

Planning the nine-month cash gap

The hardest part of cassava is not the planting or the weeding. It is the wait. A household that plants in April may not see a root until the following year, and the money has to come from somewhere in between. Plan that gap before the first cutting goes in, and decide how the household will cover it.

A flock of birds is a useful bridge. Layers give eggs every week, and broilers come to market in a few weeks. Maize or cowpea sown in the same season can bring in an early harvest. Trading or a small business alongside the field can cover basic needs. None of these replaces the cassava, but together they keep the household steady until the roots come up.

I will not quote prices for cuttings, labour, fertiliser or the roots. They change with the season and the market. Check your local market and your suppliers, and use the table to build your own figures. Our poultry business plan guide uses the same method for the birds, and the record keeping guide explains how to keep them honest.

A year-round calendar for cassava

This sequence suits a forest or transition zone cassava crop. Tie the weeding to the age of the plants, not to the date on the calendar.

In the north, a cassava crop planted at the start of the rains will reach maturity in the dry season, so plan the harvest and the processing with the dry weather in mind, and with a shorter-duration variety if you can get one.

A checklist for cassava from cutting to store

Use this checklist at planting, at weeding and at harvest. Each stage has a few points that are easy to forget, and each one costs money when it is missed.

• Confirm the variety and its duration against the rains in your district.
• Take cuttings only from an inspected, healthy field.
• Plant the cuttings the same day, with at least two or three nodes buried.
• Keep weeds out of the field for the first three to four months.
• Scout weekly for mosaic, brown streak and mealybug, and remove infected plants.
• Apply manure and fertiliser to the rates your soil test gives.
• Test-dig a few roots before you start the full harvest.
• Process the roots within a day or two of lifting.
• Plan the cash gap before you plant, and write it down.

Keep the list in the field notebook, and review it after each harvest.

Who to ask for clean stems and a patient loan

Begin with the Crops Research Institute at Kumasi, which releases cassava varieties and runs the work on clean planting material. Ask them where certified stems can be sourced in your region, and whether there has been a recent survey of mosaic and brown streak in your district. A clean source saves a season of losses.

Your district MoFA office and agric extension officer can point you to local source fields and tell you whether the virus diseases have been reported nearby. They also know whether any input support, through Planting for Food and Jobs or otherwise, covers cassava in your district this year. Check the current terms, since programme inputs change from one year to the next.

The nine-month wait is the real financing problem. A loan that runs out before the first harvest leaves you short when the roots need digging. Ask the district assembly and rural banks about repayment periods, and whether a GIRSAL-backed facility can match the timing of a root crop.

A flock fills the gap well. Layers give eggs every week and broilers reach market in a few weeks, so the household has income while the cassava grows. Our breeds page lists the types that suit a farm like this, and you can order chicks through the order form or message us at +233 24 915 1503.

For a starter plan, begin with our day-old chicks page. For the rice and sorghum guides that share a rotation with cassava, use the rice guide and the sorghum and millet guide.

Questions farmers ask