Life in the sloe lane
How does this English foragers’ favourite perform under New Zealand conditions?
Gin lovers, here’s the plant for you!
If you get a chance to visit the South Tyrol Museum of Archaeology in Bolzano, Italy you will no doubt meet its most famous resident Ötzi the Iceman. Ötzi, to whom the museum is devoted, is a hunter or possibly a shepherd who lived roughly 5300 years ago and who caused something of an archaeological sensation when he was discovered, perfectly preserved along with his clothing and equipment, in 1991. One of the things found in his stomach was the pits of the fruit of the blackthorn ( Prunus spinosa), commonly known as sloe berries. Sloe berries, the museum display notes, would have been rich in vitamins and minerals, and helped Ötzi ward off thirst as he wandered across various glaciers.
This is the first recorded instance in history of the human use of this fruit. An ancestor of the modern cultivated plum tree, Prunus spinosa, aka the blackthorn or sloe, is still a common hedgerow plant across Europe but particularly fetish-ised by English foragers, who make jams, jellies, liqueurs and – most famously – an infused gin with the small purple highly astringent fruit.
The fondness with which this plant is regarded by many British expats is something of a mystery to Neville Chun, a Lower Hutt orchardist and nurseryman, who has sold sloe trees on Trade Me for the last five years.
“Blackthorn is absolutely nothing to look at,” he admits. “It looks like a whole lot of thorny branches with small leaves. Even the white flowers, which form before the leaves appear, are small and you might miss them.”
Neville, who grows the Japanese citrus ‘Yuzu’ commercially, was selling a variety of other unusual edible plants online, including finger limes, Buddha hand citrus, pomegranates and wasabi. A customer enquired if he had blackthorn and he tracked a couple down at a now defunct Auckland nursery. These plants, which Neville suspects had been grown from seed, were a wiry tangle, with a lot of thorny growth coming as suckers from the base. The natural habit of this plant is to grow into a dense thicket – one of the reasons it is so widespread across Europe is because it fairly quickly forms a stock-proof hedge. Suspecting this growth habit would make harvesting more challenging, Neville sent budwood to Harrisons Trees in Palmerston North, and had it grafted onto plum rootstock.
“Grafting gives blackthorn a different form,” he says. “It has a nice strong leader and a nice head, and it doesn’t send up growth as suckers like it does when grown from a cutting or as a seedling grown tree.” The spinosa in the botanical name is Latin for spiny, and this plant is well named, he says. Plant carefully, away from thoroughfares, and prune regularly to keep the centre open. “If you just let it grow naturally as a hedgerow, you’d put your arm in to pick berries and never get it out!” But blackthorn is fairly easy to grow here: prolific, once they start fruiting, and self-fertile, he says. The berries or sloes form in autumn and stay on the tree until early winter. Birds do not seem to notice them, he says – perhaps because of their mouth-puckering bitterness when raw. (Although English garden and food writers wax lyrically about how the fruit sweetens up after a few frosts, and apparently then it can be eaten straight off the tree.) Neville still propagates it through grafting – he has tried cuttings for the last three years and so far has been unsuccessful at getting any to strike. It can also be grown from seed, although the seed needs to go through first a warm spell then a cold spell to break their dormancy. Naturally found growing in forest margins and open woodlands across much of Europe, this plant seems to thrive in most situations and soils in New Zealand, Neville says, although you are unlikely to get fruit in regions where it does not get enough winter chill. It seems untroubled by pests and diseases here too, he says. The wood of this tree is exceptionally hard, and prized for making walking sticks – it’s the traditional material used to make shillelagh, the stout Irish clubs sometimes used for fighting. The flowers and petals are used in various ways, both medicinally and to make teas and syrups. But it is the fruit that is the main draw for gardeners wanting to grow this plant in New Zealand, Neville admits. It can be used to make jams, jellies and preserves, and to infuse vinegar. In various European countries, sloe berries are used in pastries and they are also an ingredient in the traditional Basque liqueur patxaran, served as a digestif in some parts of Spain. But mainly, Neville admits, Kiwi gardeners seem keen to use the sloes for only one thing – to make that famous sloe gin! “I find that mainly they are bought by English expats who talk about making gin,” he says. “A few people who have bought from me mentioned they plan to use the sloe berries to make jam. But they are few and far between!”