Jackie French: Conquering a Walnut Tree

The walnut tree has won. ‘‘Oh yes,’’ I used to say blithely. ‘‘I know that walnuts/pecans grow massive, as big as the average McMansion. But as long as you prune them every winter you can easily keep them about two metres high, a lovely umbrella shape and loaded with nuts.’’

Ha.

Okay, I forgot to prune the walnut two winters ago. Last year knee surgery gone wrong meant that once again I didn’t get to prune it either. And now instead of a two-metre tall, obedient walnut tree we have a monster. Cutting it back to a ‘‘tame’’ size might kill it.

A few decades ago, only people who garden in winters where you need a coat and scarf, not just a cardigan, could grow walnut trees. Now there are ‘‘low chill’’ varieties that fruit even in the sub-tropics. There are named varieties of walnut to choose from, too. Some varieties are self-fertile – they don’t need another variety to pollinate them to get nuts. Others are sort of self-fertile – if you are lucky you’ll get lots of nuts, or at least a few – but mostly even a self-fertile variety does best if grown with another.

Plant bare-rooted walnut trees in winter or potted ones at any temperate time of the year, i.e. not too hot, not freezing and not dry unless you plan on watering it once or twice a week. Keep them moist for the first three years while they get their roots growing well and after that they should survive drought, hail and even the odd flood.

And prune to keep them to the size you want. And keep pruning every winter. Or plant only where you have at least ten square metres available for the walnut tree. Fully-grown walnuts are glorious, with a wide, fairly open canopy, dappled light below, bright yellow autumn leaves then bare branches that let the sunlight in each winter. Well-grown trees even repel flies, which is why cattle love to stand under them, and they are excellent to shade the chook yard.

When I first began walnut growing, the English/Persian walnut was the only commonly grown variety, with medium-sized nuts that fell in late autumn – or were guzzled up by the cockatoos a month or so earlier. English/Persian walnuts need cold winters and survive hot summers once established and must have very deep soil for the roots to extend into.

The following are only a few of the other varieties available. Ask your local nursery which varieties grow best in your area or find a supplier online and email them to see what they suggest for your soil, your climate and weather.

The Iron variety was bred from Chinese walnuts and are low chill, suitable for the sub-tropics, like Brisbane or coastal areas too, although they need to be protected from salt-bearing sea winds.

If you are in a cold climate – the long-johns, coat and beanie with matching scarf kind of climate – consider Wentworth. It’s slow growing, just like most cold-climate trees, and may not bear for eight years, but it gives an enormous harvest of large nuts. It also survives stinking hot summers.

A good dependable walnut is Tulare, self-fertile so it doesn’t need another variety to pollinate it. It grows quickly, and bears young. It’s a good choice in very frosty areas as it blooms late, so there is an excellent chance that it won’t be cut by late frosts. The nuts mature in early autumn, cockatoos permitting.

Franquette is an old French variety, fast-growing, self-fertile but bears better with another variety nearby. It also has the useful habit of flowering late in spring when, hopefully, frosts are over – unless, like us, you can get frosts right up till Christmas. The nuts are delicious.

If you are offered a black walnut, accept it only if you need an exceptionally hardy tree and aren’t particularly interested in eating many walnuts. It is used as a rootstock because of its hardiness, but the nuts are smaller and the ‘‘meat’’ harder to extract from the shell. It does give gorgeous timber though, if you decide to get rid of your tree once it has grown up – especially if you have pruned off side branches so it grows tall and straight.

Be stern with your walnut tree. If you want a perfect even canopy, trim it to the right shape when young. And if you wish to keep it tamed and short, don’t forget the heavy winter pruning and even some light summer pruning too. You might possibly get away with one year of neglect but, sadly, I’m pretty sure the walnut tree will win if you let it grow its own way for two.

This is the week to:

Try to catch a falling autumn leaf before it meets the ground – according to tradition each one you catch will mean a month of prosperity.
Water, unless some of that grey stuff starts falling from the sky again … what’s its name? … ah, I remember … rain.
Find where your cat, or next door’s cat who has decided your garden belongs to them too, is spending the afternoon – that is the best place to put your garden table and chairs for winter (if it’s on the top of the courtyard wall you may find this inconvenient unless you are an acrobat, or a cat).
Pick winter-juicy limes and, if you have none to pick, plant a tree … now.
Dig up the Jerusalem artichokes before you forget where they are buried and eat them baked, and with discretion, although they also make a stunning soup.
Ssee if the parrots have left you any pomegranates.
Buy the most flagrantly gaudy zygocactus to put on your window sill.