For some strange reason, some of the most delicious fruits are almost impossible to find in Aussie greengrocer shops. Lemonade fruit, for example – lemon flavour but without any acidity, as sweet as the sweetest mandarin.
However, although you won’t find the fruit in vegie shops, lemonade trees have been available from specialist growers and garden centres for at least a decade in South Australia. Another delicious citrus fruit that I’ve never seen available fresh in greengrocers (although it’s advertised as a frozen product) is Australian native Finger Lime, Citrus australasica (syn Microcitrus australasica).
This shrub or small tree is native to rainforest areas of north east New South Wales and southeast Queensland and grows 6-10 metres in its native habitat, but usually less than that in cultivation. Like many other citrus, native limes also have thorns, but their leaves are tiny, and they form intricately branched, prickly shrubs that are more open and less lush in effect than your usual citrus because of the size of its leaves.
Hundreds of small, pale pink to white flowers smother the bush in spring – quite lovely. The fruit is about the size and shape of my ring finger, and comes in a range of colours. The fruit on my ‘Rainforest Pearl’ cultivar is meant to be purple, green or pink, but they are actually an unfortunate dull brownish-purple hue, so that they look disconcertingly like something a small dog might leave on your front lawn! Come to think of it, perhaps that’s why greengrocers don’t stock this fruit!
But please, don’t be put off by my description, because what’s inside is just so exceptionally yummy you won’t care that you have a bush apparently festooned with dog poop. When you open the thin skin you find translucent, shiny green, pink or white pearls that are the size and texture of caviar. But when you bite them, instead of a fishy flavour, there’s an intense burst of tangy lime. The little beads are fantastic for cocktails, or with oysters or salmon, or for garnishing desserts and canapes, or in Thai salads. The taste is a bit different, but you can substitute for most recipes that call for lime, or even ruby grapefruit segments. The skin is edible too, like that of a cumquat, so you can slice the limes across and use them that way, and actually the skin has even more flavour than the beads. You can also make preserves, but this seems like a bit of a waste to me, because so much of this fruit’s appeal lies in its texture – I use my Tahitian limes for marmalades instead.
I bought my tree five or six years ago and until recently it’s lived happily in a very large pot, under the eaves on the north side of my house in a spot where it receives morning sun only. Chris Perry has a magnificent potted specimen in filtered light at his nursery, on the eastern side of a building. Mine loses some of its leaves over winter and looks a bit scrappy in early spring, but bounces back with plenty of new growth by summer.
As a tropical rainforest species, native finger lime won’t handle heavy frosts, but Louis Glowinski in his “The Complete Book of Fruit Growing in Australia” reports that it tolerates light frosts. My garden is quite sloping and completely frost free, and in a sheltered position it manages winters in my area just fine: that’s temperatures of only a few degrees at night, 9 – 14 degrees during the day, and lots of mist and drizzle.
I potted my tree into native mix, and fertilised in spring and summer with slow release Osmocote for Native Plants. Pests seem to be much the same as for other citrus – scale and caterpillars mainly, easily controlled organically with eco oil or Dipel or, as I did, physically removed on a modest potted specimen. Small spiders love living amongst its prickly, protective branches, so it has its own insect control!
This spring, I planted my tree into the new area, preparing the soil as I described previously for good drainage, and adding a very small amount of garden lime (Annette McFarlane in her excellent book”Organic Fruit Growing” suggests they prefer a pH of 6 – 8). Native Finger lime needs protection from afternoon summer sun in my climate, which I’ve provided, but it may receive too much midday sun until my espaliered fruit trees to the north grow a bit. I’ll see how it goes, and transplant it to a more sheltered spot if necessary.
As for most native plants, it’s essential to choose fertilisers low in phosphorous – commercial growers use NPK 15:4:11 - but well-rotted composts, manures and pelletised chicken manure can form the basis for growing in the home garden, supplemented with trace elements and potassium for a decent crop. Native finger limes need only about one quarter the fertiliser of conventional citrus, and over-feeding can cause dieback. Lots of open mulch (I use pea straw) keeps the roots cool, and I water this tree like my other citrus – once every 7 – 14 days, depending on the weather.
For more information about this terrific Australian fruit, this NSW DPI article has plenty.