Experiments with kiwifruit

Thanks to exhaustive if faintly intrusive matchmaking with a ladder and a paintbrush back in October, we have a bumper crop in the kiwi arbor.

Four years ago the northern wall of the kitchen was occupied by a dank lean-to, usable only for turning your bike into the kind of rust-bucket that can be safely left overnight at train stations.  But we don’t need these kinds of amenities.  If you leave your bike unlocked outside the pub in Berowra, it might get taken by a drunk on his wobbly way home, but if it does, the bartender will recognise the miscreant on the CCTV footage and leave a friendly message on the guy’s answering machine to return it in the morning.  Even the pelotons of MAMILS leave their featherlight carbon-fibre bikes untethered at the end-of-ride coffee shop.

great sky near Berowra for crop

Blue skies over Berowa

So, with no need for a bespoke bicycle corroding zone, we replaced the corrugated iron over the frame of the lean-to with couple of precociously fruitful Sweetie kiwifruit vines, a low chill variety from Daleys Fruits in Maleny.  Last year we had a handful of fruit that the possums seemed enjoy.  If they’re planning to eat the whole crop this year they’d better be hungry.

I’m feigning disinterest in what happens to my kiwi harvest but let’s be real – the last few years have turned me from a lentil-eating hippie into an antipodean Mr McGregor, the pointlessly enraged gardener who would love to turn Peter Rabbit and his fluffy little brothers and sisters into a delicious warming casserole.

Don’t get me wrong, while I do covet the infinitely soft possum-fur jumpers that vengeful New Zealanders knit from our invasive marsupials, I’m not spending my nights under the kiwi trellis with a gun in my hand.  That said, the rugby-league style gum shield I wear overnight to stop me grinding my teeth to dust (expensive, but since it doubles as a contraceptive, probably good value) does date from about the time I started trying to grow fruit in the backyard.

No, I’m taking a less brutal and more scientific approach to harvest-management.  I have a control – the fruit I’m leaving untouched on the vine.  And I have two intervention groups – there’s the kiwis I’ve picked early, hard as furry brown rocks, and left to ripen in the fruitbowl, and then there’s the bunches I’ve put into protective custody in mesh exclusion bags.

I maintain a cautious optimism that I will get to eat at at least some ripe fruit.  This upbeat attitude has nothing to do with early success.  While commercial kiwifruit are usually picked unripe and can be kept on ice for two months or more, so far my early harvest has withered slightly but maintained a mouth puckering acidity, as evidenced by our school holiday Ph testing activity.

I can’t seem to kick the habit of growing red cabbages, despite the fact that no one in the house, myself included, really wants to eat them.  They’re just so pretty!

Purple cabbage leaves wide crop

Red cabbage abstract

So apart from feeding the leaves to the cabbage white butterflies that my 9 year old keeps in her bedroom as “pets”, what else can you do with leafy brassicas too chewy for coleslaw?  Well, you can boil them up and use the purple cooking water as a very cool litmus test.

There’s nothing kids like more than squeezing out half the toothpaste tube, making potions out of bicarb, tomato sauce and milk, or filling every single glass in the kitchen with disgusting viscous liquids.  We even ended up with a boys v girls Ph contest – boys obviously preferring alkaline household products, while as we all know, historically girls inevitably favour acids.  Including our long-cossetted kiwifruit, which turned our cabbage water a pleasing deep pink.

Litmus test from the side cropped

The results of the purple cabbage litmus tests

Early indications are the mesh exclusion bags aren’t doing much better than the fruit bowl in the protection and ripening caper. I can’t remember a pre-masticated fruit being present when I tied the bag around this bunch.  We seem to have a Houdini of the rodent world somewhere on the premises.  The outcome so far is not as dismal, at least, as 2014’s doomed attempt at protecting peaches.  The mammal and insect pests deployed a pincer movement – rats gnawing a hole in the bags and fruitflies pouring through to finish the job.

No, my optimism about getting to wrap my laughing gear around some home-grown kiwifruit sorbet is based on the barely nibbled fruit discarded the ground under the vines.  Whatever is chowing down on my crop just isn’t very keen.  Perhaps they have a sweet tooth.

How, I hear you ask, can you tell when to harvest your kiwifruit?  Well, apparently if you cut one open and the seeds have turned black it’s ready for harvest: its starches will turn slowly to sugar in storage. But there is a more scientific way.  Sugar solutions refract light, particularly polarised light, differently from your ordinary tap water. So your go-to-device for measuring sweetness (reported in Brix) is a refractometer.  The savvy kiwi farmer picks her fruit at a bit over 6 degrees Brix, it seems.  Let’s just hope the brush tailed possums can’t tell their pouches from their polarising light and the satin bowerbirds couldn’t track down a refractometer on ebay.

Tropic Snow

First peach blossom closeup

The first peach blossom of spring winter: TropicSnow, a low chill variety.  It has produced Cezanne-worthy fruits from its second year here – but so far I haven’t beaten the critters to them.

This year! This year! Mesh exclusion bags!  Fruit fly traps!  Pheromones!  Chooks given the run of the pepino groundcover – dig, dig my sharp clawed friends! – on the condition that they utterly exterminate all fruit fly larvae.  I’m toying with installing a band of slippery plastic (or inedible metal?) around the base of the tree to at least give the possums and the rats a bit of a challenge (or some core body exercise?).  Tiger poo??  Whatever it takes!

Peaches apparently only live for a few years, and I simply refuse to have the damn thing die before I wrap my laughing-gear around some luscious sun-warmed home-grown fruit.

Critters with kidneystones

It was all going so well.  The warrigal greens were flourishing, even without being regularly urinated on.  Deep-rooted sorrel was a stalwart when pretty much nothing else was happening in the garden at all. Both were in high rotation in the kitchen.  I’ve always been a bit cautious about using them raw, since, along with other garden staples like rainbow chard and rhubarb, both of them have a fair bit of oxalic acid, which if you overindulge and/or are unlucky can cause kidney stones (although the idea that the latest “miracle foods” might have the potential to be dangerous causes outrage in some) .  Given that rainbow chard, which is also quite high in oxalates, always has escaped animal attention, it seemed too much of a coincidence that the beasties seemed to leave these plants alone: those smarty pants critters were sensibly avoiding intestinal distress .

But look at my poor greens now:

Chewed sorrel Chewed warrigal greens

Something is clearly tucking in.

There are a number of possible suspects.  Judging from the robotic squeaks and buzzes in the undergrowth, there are satin bowerbirds still around.  Rumour has it they are fond of fresh shoots – I blame them for the tatty foliage of my now past-it Purple King beans.  It could be the chickens of course, but though the four new girls spend a lot of time in the area where the warrigal greens are (or were… *sniff*) only tricksy skinny Shyla regularly scoots through the gap in the bamboo gate into the veggie patch where I’ve planted the sorrel and, more recently, rhubarb (the leaves of which *are* toxic to humans, and have also been chewed in the last few days).  So, in the absence of an extensive literature review on comparative rodent, marsupial and human tolerances of oxalic acid (I have tried!), I’m blaming rats or possums.  I guess definitive evidence would consist of creatures with particular glossy pelts.  Or creatures rolling around with excruciating abdominal pain. Or both.

Do possums see in technicolour?

Tamarillos: what a great fruit for inept, part-time gardeners!  Stupendously quick to grow – to a couple of metres in not much over twelve months.  Producing a crop in less than two years and in a shady spot too, tucked in amongst monstera deliciosa, naranjillas and a dwarf Cavendish banana in the lee of the neighbour’s tall pine tree, with filtered light in summer and just a touch of winter sun.  The egg sized fruits are quite pleasant to eat: flesh with the texture of a honeydew melon and with an overtone of passionfruit.  I like the big bright green tropical leaves and the fact that fruit flies seem to leave them alone.  But best of all, Matimba (as our youngest named the baby tree when it went in) didn’t seem to be pestered by possums.  Since the fruits dangle  from slender pendulous branches I wondered at first if the critters couldn’t make it to where the action was.  Then I thought perhaps they hadn’t spotted them yet, remembering how my figs and beans went untouched for a year or two.

And then recently I spotted a green but nibbled fruit under the tree.  Obviously the contents weren’t to the liking of the thief – not quite ripe enough, perhaps.  It might well have been an optimistic bird that did the dirty work.  But given that tamarillo fruits quite distinctly change in colour as they ripen – gold in the case of Matimba and red in the case of her as yet non-fruiting little sister Molly – this evidence of mid-snack mind-change made me wonder: “Do possums have colour vision?


I realised only recently that primate colour vision is actually pretty unusual amongst mammals, whose ancestors swapped technicolour for better night vision while hiding amongst the shadows, waiting for dinosaurs to leave the party.  Humans, primates and monkeys have a kind of gerry-rigged third cone that gives us an in on the neat seed dispersal system fruit-bearing plants sorted out with birds and their dinosaurian tetrachromatic eyes.  Like parrots, we can spot a ripe fruit against a canopy of green leaves (although we don’t get to see the UV spectrum, which is disappointing).  Okay, there are other explanations for primate colour vision – like spotting tasty red-hued fresh leaves – but I’m sticking with this one for now.  Interestingly, colour-blind humans, primates and monkeys (particularly males) are still unusually common.  It seems that colour-blind individuals are great at seeing through camouflage, so a sprinkling of dichromatic members of the group serving as predator-spotters does a mob of monkeys or apes no harm at all.

Pulling out of the fascinating vortex of animal colour vision research and returning to my original question, what about possums?  With the ubiquity of brushtailed possums in suburban houses and gardens in Australia, surely someone would have a definitive answer on this one.

It turns out that marsupial colour vision has been a hotbed of academic research over the last fifteen years.  Until the early noughties it was assumed that marsupials, like most placental mammals, were dichromats, with pretty limited colour vision.  But then researchers identified that some marsupials, like the fat-tailed dunnart, the honey posssum and the quokka, were trichromats (as indeed were the ancestors of platypus and echidnas, the monotremes).  Some marsupials, like the poor old tammar wallaby, do seem to have the same rather average colour vision as the placentals.

Brush-tailed possum vision is so cutting edge that Lisa Vlahos’ PhD on it, completed in 2013, hasn’t even been published in science journals yet.  But, based on the annual reports at the Vision Centre at ANU (sadly I haven’t been able to access her endearingly named PhD thesis “Possum Magic”) it look like brushtails can see part of the UV spectrum, but can’t distinguish between white and green light: more like dogs than chickens, they’re red-green colour blind.

Which might explain my chewed and rejected green tamarillo fruit. Or not.  But it was fun finding out anyway!

An inexpert Anglo’s guide to identifying bush foods in the garden

Step 1. Come up with a list of possibilities through the interweb or other trusted source.

Step 2. Purchase, potentially with some difficulty, from a suitable vendor of native plants.

Step 3. Bring finds home and situate them carefully in the garden, giving appropriate thought to aspect and drainage.

Step 4. Wait. If, after some time, you find a patch of thoroughly excavated soil or even a few macerated fragments of greenery where your precious purchase was previously located, congratulations!  With the help of your hungry non-human assistants, you have identified an edible native plant!

Okay, it doesn’t always work that way, but I’m feeling slightly embittered since a second generation of bulbine lily has bitten the dust courtesy of the advanced culinary sensibilities of our trusty flock of brush turkeys. Thanks, guys!


The apple berry vine was, I think, cleaned up by the possums.  The chocolate lily has suspiciously vanished from its new spot sheltered in the fringes of the prolific and obviously insipid tasting blue flax lily.  Dormant in summer, perhaps it will pop up again next year, but after reading descriptions of its “delectable” aroma and tubers that are edible both raw and roasted, I am not optimistic.  I have a strong suspicion, based solely on the fact that the regularly nibbled growing tips of the specimen outside my kitchen, that the Fraser Island creeper may also have some undocumented uses as a pot herb.  Don’t try this at home, though… unless you are a brush turkey, in which case, help yourself.