Bùi Thụy Đào Nguyên, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=16703632

This month, it’s time for something completely different as we step away from the ordinary and take a look at the much-maligned but eager-to-please choko.  You may or may not have heard of this strange pear-shaped “is it a fruit, is it a vegetable?”  Those in New Zealand’s northern climes are perhaps more likely to be familiar with this outlandish member of the Cucurbitaceae or gourd family.  Maturing in late autumn to early winter, and with good storage potential, it is a handy substitute for cucumbers and zucchini in the months when these vegetables are absent.  With this gap-filling potential, I believe chokos deserve a higher profile – and they may help dispel the frustration experienced when you read a recipe in the newspaper in July that calls for out-of-season produce. 

Chokos: a short family history

The choko, Sechium edule, hails from Central America and from there made its way around the world, assisted by the ‘Columbian Exchange’ as many plant species (among them tomatoes, potatoes and maize) travelled from the Americas to new continents following Christopher Columbus’ 1492 voyage.  Now widespread and a mainstay of multiple cuisines, it is known by a number of common names in different countries: the most common outside of Australia and New Zealand is chayote, from Spanish.  Things get a little more interesting in Haiti and the state of Louisiana in the USA where it is known as mirliton, pipinola in Hawaii, christophene in the Caribbean, brionne in France and Buddha’s palm or hands in China (owing to the lobed fruit looking like hands folded in prayer).

Suitable climates and growing conditions

Choko vines have a few characteristics that set them apart from their other cucurbit cousins.  The plant is actually perennial, rather than a summer annual like pumpkins or cucumbers.  The foliage will die back after being hit by frost in late autumn and winter but will re-sprout from the dormant crown region in the spring.  In milder, frost-free climates or years with mild winters the degree of die-back will vary, and in warmer years you may find growth is simply knocked back rather than killed off completely – giving the plant a head start in spring.  In the lower South Island, you will probably need to grow chokos in a covered environment to bring fruit to maturity, but given the amount of space required, this may not be a practical exercise!  The legendary garden columnist Jonathan Spade (pseudonym of Noel Chappell) advises gardeners to “warn their neighbours” after planting a choko, as “Indeed, were it given garden room there would be little about the place that it would not embrace, like an octopus, or a python”.  Plants will live for up to eight years, but there is a noticeable decline in fruitfulness over time, and to maintain production it is recommended that you replace the plants every three years – in my experience, it also takes plants two years to produce fruit, but this could be a regional effect (upper South Island).

Plants do best situated in a sheltered spot in partial shade or full sun, but are not overly heat tolerant in the height of summer, instead thriving when temperatures are between about 15-20°C.   Like other cucurbits, chokos need plenty of space to ramble.  Due to the large size of the plant, and also its susceptibility to root rots, chokos are not suitable for container culture.  The vines are vigorous and require some form of support – a fence is ideal, and they will also happily grow to a height of ten metres or more up a tree, with little detriment to the host.  My plant has happily scrambled along a fence and up a nearby willow tree this year, and I’ll harvest the remaining fruit when I cut and pull down the aerial stems.  Under cultivation overseas, the vines are often trained on wires and pergola trellises for ease of harvest. 

Like many cucurbits, chokos are sensitive to fungal diseases affecting the plant’s roots, and will therefore struggle if planted in heavier clay soils.  They are best planted in well-drained soil types. Loams and sandy soils are ideal, but care must be taken to avoid water stress in the summer months with regular watering.   

Propagation and culture

There are three options for propagating choko plants:

The most common method is by planting a whole fruit – if you leave one on your bench or windowsill before long several sprouts will emerge from the broad end of the fruit (the end that looks like the mouth of a sock puppet).  This can be turned into a fascinating biology lesson for kids – the seed quite happily germinates from within the fruit, with the flesh providing moisture and nutrients.  In the spring, after the danger of frost has passed, and before the vine takes over your kitchen, prepare your planting site and dig in some compost, rotted manure or blood and bone.  Place the sprouted choko on its side and cover with about five centimetres of soil.  The broad end should be angled slightly lower than the stem end, which should be left exposed. Water well.

You can also take shoot tip cuttings in spring or summer, planting them in compost and placing them on a heated bed to ensure a good strike.  If you are digging the tubers, these can be broken into pieces – make sure there are a couple of leaf shoots on each, plant them into compost and keep watered.  Once established, side dress with fertiliser once or twice throughout the growing season – my preference is to use sheep pellets and a few doses of liquid seaweed foliar feed.                

Don’t panic if you can’t see any flowers on your choko vine well into the growing season - choko flowering is initiated by shortening day length, and as such in the New Zealand climate the flowers may not appear until late summer or early autumn.  In the top of the south, flowering occurs around mid-April and harvest starts about a month later.  As with other cucurbits, flowers are male or female and are insect pollinated.  In favourable seasons, the rate of fruit growth can be dramatically fast and specimens can reach close to 1 kg in weight.  The optimal harvest size is 10-20 cm in length, with less mature fruits being less sweet and more suited to savoury dishes.  Mature vines can produce 50-100 fruit.  Depending on the variety, the resultant fruit may be completely smooth or covered in small spines – most New Zealand types are green, but others found overseas can also be yellow to cream in colour, and some are covered with longer, chestnut-esque spines.

Once established, chokos are easy-care – though they may require judicious trimming to keep them trained and contained to the space available.  As long as the water is kept up during dry periods, and adequate fertiliser is applied, a bountiful crop should follow.  Pest and disease issues are minimal to non-existent, apart from the aforementioned root rots.  When the plant dies back in winter, you can cut back the old, dry stems and mulch the root zone.     

What to do with your crop

This should probably be more accurately headed “what CAN’T you do with a choko?”  The choko’s popularity worldwide no doubt stems from its versatility: virtually all parts of the plant are edible.  Most obvious are the pear-shaped fruits, which can be eaten raw or cooked in both sweet and savoury dishes.  What do they taste like?  The way I describe them to the uninitiated is that they taste like the smell of a freshly mown lawn – grassy, but not unpleasantly so.  Many say bland, and it is true that chokos are a good bulking agent and tend to take on the flavour of whatever they are cooked with.  Urban legend has it that chokos, which grow astoundingly well in Australia, were utilised by McDonald's in that country as an inclusion to stretch the apple content in their pies.  The fruit is best peeled before use and has a crisp but not overly hard texture.  The large single seed inside the centre of the fruit is also edible, the young leaves and stems (best harvested to the second leaf on the growing tip) can be steamed or stir-fried and the starchy tubers can be boiled, fried or roasted much like a potato.  I’ll be trying the latter this year for the first time, as my plant has reached replacement age, hence it’s a good time to harvest some tubers.  Older leaves and the tubers are also useful stock fodder, and the dried stems have been used to make a type of twine for various uses – when you cut back your vine at the end of the growing season you’ll understand why they take a bit of getting through. 

What to do with a bumper crop?  Work your way through young fruit sliced raw in salads and with dips, and in anything that calls for cucumber.  Include in stir fries, as a substitute for zucchini in other hot dishes, and lightly cooked as a side dish with butter, salt and pepper.  Use more mature, sweeter fruit to bulk up jams and preserves – Aunt Daisy provides at least half a dozen suggestions in her popular Cookery Book #5.  Chokos never go out of fashion!  Many people have successfully preserved chokos in their own right as a substitute for pears...and lived to tell the tale.  Chokos also make great pickles, which retain the fruit’s crisp texture (see recipe below).  Trawl the internet for ethnic specialties from practically every country under the sun.  And if you still have leftovers, as one pithy entrant in a New Zealand Gardener call for ideas on how to use up a choko glut suggested, you can “throw them at your neighbours”. 

Chokos have a strong diuretic effect, so much so that excessive consumption can lead to hypokalemia, where excessive amounts of potassium are lost from the body resulting in too low a concentration in the blood.  So consume them with restraint.  In the past, the plant was used in the treatment of kidney stones, and the well-preserved nature of mummified bodies (still in existence today) of the choko-phile residents of San Bernardo in Colombia is attributed to the fruit’s purported cell-regenerative qualities…take from that what you may!

CAUTION: Don’t confuse S. edule with the noxious weed moth plant, Araujia hortorum, sometimes referred to as false choko – more information here: https://www.weedbusters.org.nz/what-are-weeds/weed-list/mothplant/

Pickled choko spears

1 kg choko fruit (4-6, depending on size)
2 tbsp plain salt
3 cups cider vinegar
½ cup raw sugar

1 tsp pickling spice OR 1 tsp yellow mustard seed plus a sprig of dill per jar OR one bay leaf and a few whole peppercorns per jar.

Peel chokos, remove the seed and slice into quarters, then thumb-thick spears. Place in a glass, plastic or stainless steel bowl, sprinkle with salt, mix well, cover, and leave for an hour to dry brine.

Heat six clean glass jars (approximately 400 ml capacity) in the oven at 125°C for 30 minutes and boil their lids in a saucepan of water on the stovetop for 10 minutes. 

Bring the vinegar, sugar and spices to a boil in a large saucepan and simmer for 5-10 minutes.  Drain the liquid from the chokos, but don’t rinse.  Using tongs, remove the jars from the oven and place them on a wooden board or tea towel.  If using dill or bay leaves, add these directly to the jars.

Pack the choko spears evenly into the jars and ladle over the hot vinegar mixture.  Screw on the boiled lids and seal tightly.  Store in a cool dark place, and wait for at least three weeks before consuming.  These should store well for two years.

Anna-Marie Barnes is an active member of the New Zealand Tree Crops Association who endeavours to grow and preserve as much of her own fresh produce as possible.  When the weather’s no good for gardening, she can usually be found inside working on a batch of homemade cheese or soap.    

The New Zealand Tree Crops Association is a voluntary organisation promoting interest in useful trees, such as those producing fruit, nuts, timber, fuel, wood, stock fodder, bee forage and other productive crops.  Find out more about the NZTCA here: https://treecrops.org.nz/