Fertilising guide

How to fertilise Cashew (Anacardium occidentale)— schedule & NPK

Also called cashew, cashew apple tree.

More about cashew

About Cashew

Anacardium occidentale · also called cashew, cashew apple tree · edible

Cashew is a spreading tropical evergreen tree producing a swollen, juicy cashew apple topped by the kidney-shaped nut. The raw nutshell contains caustic urushiol-type oils (it is a poison-ivy relative), so nuts must be roasted before eating. Fast-growing, drought-tolerant once established and frost-tender, it is a productive lowland tropical orchard tree.

Growth habit: Low-branching, spreading evergreen tree with a dense, broad, often umbrella-like crown; fast-growing and capable of fruiting within a few years.

Watch for — Caustic nutshell oil (CNSL): The raw shell oozes urushiol-like oil that burns skin and must never be inhaled when roasting. Always roast nuts before handling or eating; wear gloves when processing.

What fertiliser cashew actually wants — and why

Cashew 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 cashew: 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 cashew, 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 cashew:

Feed with a balanced fertiliser through the growing season, increasing potassium and phosphorus to support flowering and nut fill. Young trees respond to nitrogen for canopy growth; mature trees benefit from organic mulch and micronutrients. 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).

The dormant-season rule matters more than the exact interval: skip feeding entirely when cashew 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 cashew

Follow the crop-feed label rate for cashew — 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 cashew first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the cashew watering schedule.

Signs you are over-feeding cashew

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

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 cashew

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 cashew 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 cashew 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 cashew

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 cashew — frequently asked questions

What fertiliser does cashew 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. Cashew 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 cashew?

Feed with a balanced fertiliser through the growing season, increasing potassium and phosphorus to support flowering and nut fill. Young trees respond to nitrogen for canopy growth; mature trees benefit from organic mulch and micronutrients. Feed with a balanced fertiliser through the growing season, increasing potassium and phosphorus to support flowering and nut fill. Young trees respond to nitrogen for canopy growth; mature trees benefit from organic mulch and micronutrients. 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 cashew?

What does over-feeding cashew 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 cashew 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 cashew?