Fertilising guide

How to fertilise Cassava (Manihot esculenta)— schedule & NPK

Also called Manioc, Yuca, Tapioca plant, Brazilian arrowroot.

More about cassava

About Cassava

Manihot esculenta · also called Manioc, Yuca · edible

Cassava is one of the world's most important starchy root crops, providing a calorie staple for hundreds of millions across Africa, South America, and Asia. Woody-stemmed shrub with large, palmate leaves and thick, starchy roots. Critical safety note: raw cassava contains cyanogenic glycosides and is toxic to both humans and pets until properly processed.

Growth habit: Upright, branching woody-based tropical shrub

Watch for — Mealybugs: Colonies on stems and root crowns stunt growth. Introduce parasitic wasps (Anagyrus lopezi) as biological control; use neem oil for minor infestations.

What fertiliser cassava actually wants — and why

Cassava feeds in two distinct phases — balanced to build the plant, then high-potassium the moment flowering starts to set and fill a heavy crop.

For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for cassava: match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.

How often to feed cassava, and which months

Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For cassava:

The dormant-season rule matters more than the exact interval: skip feeding entirely when cassava is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.

What strength to mix for cassava

Follow the crop-feed label rate for cassava — these are calibrated for hungry vegetables. Consistency through fruiting matters more than strength; erratic feeding causes problems like blossom-end rot.

Feeding always goes onto already-damp soil, never dry roots — water cassava first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the cassava watering schedule.

Signs you are over-feeding cassava

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for cassava:

Vigorous dark-green leafy growth but few flowers or fruit (excess nitrogen).
Lush foliage hiding the crop; soft growth prone to pests and disease.
Salt crust on the soil and scorched leaf edges in containers.

Signs you are under-feeding cassava

Pale, yellowing lower leaves and stunted growth.
Small fruit, poor set, and a quickly exhausted plant.
Blossom-end rot and weak cropping from erratic or insufficient feeding.

If the symptoms point at watering, light or roots rather than nutrition, the full cassava care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

In containers, fertiliser salts build up fast — water cassava thoroughly so excess drains from the base each time, and flush pots with plain water every few weeks to prevent a damaging salt build-up.

Organic vs synthetic feeds for cassava

Organic options

Garden compost or well-rotted manure dug in before planting, plus a liquid comfrey or seaweed feed once fruiting starts. UK: comfrey feed or organic Tomorite; US: Espoma Tomato-tone or Neptune's Harvest. Builds soil and feeds in one.

Synthetic / liquid feeds

A balanced feed at planting then a high-potash tomato feed in fruiting — UK: Growmore at planting then Tomorite (Levington) or Phostrogen; US: a balanced 10-10-10 then Miracle-Gro Tomato or a bloom booster.

Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.

Fertilising cassava — frequently asked questions

What fertiliser does cassava need?

Balanced (even N-P-K) at planting for roots and frame, then switch to a high-potassium ("high-potash") tomato-style feed once the first flowers open — potassium is what sizes and ripens fruit, not nitrogen. Cassava feeds in two distinct phases — balanced to build the plant, then high-potassium the moment flowering starts to set and fill a heavy crop.

How often should I feed cassava?

Cassava grows in poor soils but benefits from a moderate application of balanced NPK fertiliser (avoiding excess nitrogen) at planting, and a potassium-rich top-dress midway through the growing season to support root bulk. Over-fertilising promotes leafy growth over root development. Cassava grows in poor soils but benefits from a moderate application of balanced NPK fertiliser (avoiding excess nitrogen) at planting, and a potassium-rich top-dress midway through the growing season to support root bulk. Over-fertilising promotes leafy growth over root development. So: a balanced feed or compost at planting, then a high-potash liquid every 1-2 weeks from first flower through harvest across the main season (spring through early autumn).

What strength of feed for cassava?

What does over-feeding cassava look like?

Vigorous dark-green leafy growth but few flowers or fruit (excess nitrogen). Lush foliage hiding the crop; soft growth prone to pests and disease. Salt crust on the soil and scorched leaf edges in containers. Staying on a high-nitrogen feed once cassava starts flowering is the classic error — you get a huge leafy plant and a disappointing crop. Switch to high-potash the moment flowers appear.

Should I flush the soil of cassava?