How Do Cashews Grow? From Flower to Whole Nut, Harvest and Processing

It's easy to forget how much work sits behind a handful of cashews. The tree takes years to give a good crop, the nut grows in a very unusual way, the shell hides a harmful oil, and the kernel inside is fragile. Getting it out whole, clean and pale takes a series of careful steps. This guide follows a cashew all the way from the flower to the whole nut.

A cashew tree grown from seed usually produces its first few nuts after around three to five years, and it takes longer, often five to eight years, before a farm gets a steady, worthwhile harvest from it. Trees grown from improved, grafted plants can start sooner, sometimes giving their first nuts within two or three years.

After that, a healthy tree keeps producing for a long time, often 25 years or more. That means a cashew orchard is a long-term commitment: a farmer plants it knowing the real return comes years later, and the same trees may feed the family for decades.

In Sri Lanka's dry zone, cashew trees flower from around November into the early months of the year, as we explain in our guide to where cashew trees grow. The small flowers are pollinated by insects, and once a flower is pollinated, the fruit starts to form.

From pollination, the fruit takes roughly two to three months to ripen, which is why the harvest in Sri Lanka comes mainly around March and April, and sometimes into May. The timing shifts a little from year to year with the weather.

A cashew isn't like other nuts, because it grows outside its fruit. What looks like the fruit, the juicy yellow or red 'cashew apple', is actually the swollen stalk of the flower. The true fruit is the grey-green, kidney-shaped shell that hangs from the bottom of it. Inside that shell is a single kernel, the cashew we eat.

The cashew apple is soft and juicy, with a sharp, sweet taste, and in many places it's turned into juice or jam. But the nut is the valuable part, and it's the part that needs the most careful handling.

When the fruit is ripe, the nuts are collected, many of them picked up from the ground after they fall. Each nut is twisted off the cashew apple by hand. It's slow work, because every nut has to be gathered individually, and one tree gives only a few kilograms of raw nuts in a season.

Freshly picked nuts hold a lot of moisture, so they're spread out in the sun to dry, usually for two to three days. This brings the moisture down to a safe level, so the nuts keep well and don't go mouldy. After that they're stored in sacks until they go for processing.

The soft-looking shell is the biggest challenge. Between its layers is a dark, caustic oil that burns and blisters the skin. That's why you never see cashews sold in the shell, and why raw cashews from a shop have already been heated and carefully shelled. We cover this in our post on raw vs roasted cashews.

At the processing unit, the dried nuts are cleaned of dirt and stones and sorted by size, so the next steps treat similar nuts together. They're then heated, usually by steaming, which softens the shell and makes it easier to open without breaking the kernel inside. This heating step is also part of why a 'raw' cashew isn't truly raw.

Next, the shell is cut open and the kernel is lifted out. Done by hand with a cutting tool, or with a machine, it takes skill: the shell is an awkward curved shape and the kernel sits tightly inside it, so a cut in the wrong place cracks the nut. Workers protect their hands from the shell oil while they work. This is the step where most cashews get broken, and it's why whole nuts are harder to get than pieces.

The kernel is still covered in a thin, papery brown skin. The kernels are warmed gently to dry them and loosen the skin, which is then peeled off by hand or with a machine. The kernel underneath is the pale ivory cashew you recognise.

Finally, the peeled kernels are sorted by size, colour and whether they're whole or broken. Whole kernels are graded with a W number, such as W240 or W320, and pieces and splits are graded separately. You can see how this works in our guide to cashew grades.

The graded kernels are packed in sealed bags or tins to keep out air and moisture until they're needed. From there, they're roasted for flavour, as we describe in how Sri Lankan cashews are roasted, and seasoned if they're going to become something like Deviled Cashew.

Put it all together and it's easy to see why whole cashews are not cheap. The tree takes years to mature, each nut is picked by hand, only a small part of a raw nut ends up as a kernel (roughly a quarter or less by weight), and every step after harvest can break the nut. The kernels that make it through whole are the ones that sell at a higher price. Our post on kaju prices in Sri Lanka explains the other things that move the price.

We source our cashews from farms in Puttalam, and we roast them to order in small batches. Browse the range in our shop, and you can compare the options on our price guide.

If you enjoyed this, you might also like our guides to the history of cashew in Sri Lanka, the story behind the word kaju and what burnt cashews are.