Walnuts 101: How to grow, store and cook walnuts

It’s technically not a nut, but Kristina is nuts for this nut.

Words: Kristina Jensen

When we returned to the property in the Marlborough Sounds where we are care-takers, we found that there was a new member of the family waiting to meet us.

Sally (originally christened Schnitzel) is an adorable little black piglet. My brother warned my husband Paul that we would never be able to eat her if she had a name.

Fortunately, the eating of the piglet is not my personal concern. While I feel concerned for Sally, she does belong to someone else who will do the dastardly deed when the time comes.

Hopefully, we won’t be here to witness it because (a) my husband really likes pigs, and (b) we are mostly vegetarian (for many different reasons).

One of the great perks of living in Clova Bay is harvesting nuts from a huge old walnut tree. According to one local, it is possibly over 100 years old, although there doesn’t seem to be a consensus on its age. Whatever the figure, it is a massive specimen.

Our bedroom looks right out onto it. We get to witness the gauntlet of seasonal change as the tree moves through its cycles of buds, leaves, catkins, green developing nuts, ripe nuts, and finally its bare skeleton through winter.

We nickname the developing lime-green nut shells ‘green bombs’. This is due to the incredible crash they make when they fall off the tree onto the roof above our heads and wake us up in the wee hours of the night.

The nuts from this particular tree are quite big and each one in its fresh green suitcase weighs around 70g. That’s about the weight of a jumbo egg.

Kristina and her favourite walnut tree.

When I first came across the recipe for a nut tart, it called for pecans. In North America, where pecans grow, people battle with squirrels to get the nuts. Here we are in a war with possums, rats, weka, and now potentially Sally.

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If it is a pesky possum (usually the reason they are falling at night), Paul reluctantly gets out of bed to shoot the blighter out of the tree.

Before you wag your finger at me, I know that my concern for the pig being eaten and lack of concern for the possum being shot are directly at odds with each other. I offer nothing in my defence. However, I can lock the pig up. Covering the tree so possums can’t get it at it is not an option.

My Canadian-born husband has very fond memories of pecan pie. Unfortunately, I find the pecans sold out-of-shell here in New Zealand are often rancid (many oils in nuts go rancid when exposed to air).

But what about walnuts? Walnut tart is a favourite in France, known as tarte aux noix. The French version is caramelised and made with cream, an over-indulgence that is so extremely rich, small portions are advised.

READ MORE: Recipe: Quick and Easy Walnut Tart

The same could be said for this walnut tart too.


Walnuts like a dry climate, with a high summer temperature and winter chilling (down to -10°C). Late spring frosts can be a problem for some cultivars. Walnuts will grow in humid areas but there is more risk of disease.

Grafted trees are more expensive to buy but will produce nuts after 3-5 years, vs 10-15 for seedling-grown trees.

1. Shannon

Height/spread at maturity: 15m x 12m
Growth rate: fast

Most blight-resistant walnut cultivar and does well in most parts of NZ. It was also the heaviest and most consistent cropper (25kg a year, 11g per shelled nut) in NZ Tree Crop trials over several years.

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2. Rex

Height/spread at maturity: 12m x 15m
Growth rate: medium

Widely planted, some blight resistance, heavy cropper of a small tasty nut that stores well, hard to crack which is good if you have rats, doesn’t tolerate wet feet.

3. Meyric

Height/spread at maturity: 15m x 12m
Growth rate: fast

Big tree that is prone to blight and doesn’t tolerate wet soils but is good in frost-prone areas (late to flower) and has good crops of easy-to-open sweet nuts that store well.

READ MORE: 10 things to know about growing walnuts for profit


• The first lot of nuts to fall will still have vestiges of their casings attached and are often diseased or just no good. Wait until they are coming down completely free of their green or blackened shell.
• Get the nuts off the ground as quickly as possible. Dry them by spreading them out in the sun for 2-3 days (on a deck or in a trailer are two good options).
• Once dry, hang them in onion sacks in a shed or garage which gets warm on sunny days. Hang them high so rats can’t get at them.
• If you have too many to crack all at once, and have the space, keep them in the freezer in their shells.
• Raw walnuts are way too acidic for my taste. Paul and I crack our walnuts throughout the winter and roast them in an oven set at 100°C for 20 minutes. They seem to stay fresh and crisp for months when treated in this way, kept in an airtight jar.

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• Technically walnuts are not nuts but drupes. A drupe is a type of fruit in which the outer fleshy part surrounds a shell or ‘pit’ with a seed inside. Other examples of drupes are pecans and almonds, peaches, plums and cherries.
• Walnuts have a dastardly little trick to prevent any competitors stealing nutrients from around their roots. They are allelopathic, which means that all parts of the plant exude a chemical toxin called juglone that inhibits the growth of nearby plants.

Blue Cheese, Pear and Walnut Pizza

The strong flavour of blue cheeses pairs well with other strongly-flavoured foods and beverages. Check out a divine gourmet pizza recipe from Whitestone Cheese here.

Roasted Walnuts

NZ walnut growers share their tried and tested walnut recipes on their website here.  This is an easy-to-make snack to serve with drinks.


2 tbsp butter
2 tbsp olive oil
300g walnut halves or pieces
3 tbsp fresh rosemary, finely chopped
1 tsp ground paprika
2 tsp salt


Preheat the oven to 180°C.

Melt the butter and oil in a large roasting pan, then add the nuts and toss lightly to coat. Spread out the nuts to form a single layer, then sprinkle with the rosemary, paprika and salt.

Bake for 20–25 minutes, shaking frequently, until they are browned. Take care not to overcook them as they can easily be scorched and spoiled at this stage.

Tip onto paper towels and allow to cool.

Source: WalnutsPlease.

Recipe: Quick and Easy Walnut Tart

10 things to know about growing walnuts for profit

NZ Lifestyle Block This article first appeared in NZ Lifestyle Block Magazine.
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