oranges

What a winter we’re currently experiencing – colder than usual, extremely wet to boot and seemingly without end, with the added misery of colds, flu and Covid circulating.  I pity those currently on holiday with children in tow, not exactly the weather to be out and about in.  It’s not good gardening weather either, thank goodness most plants are dormant and need little maintenance right now.  Today is one of those rare fine days and I should be out in the fresh air, but an approaching deadline means computer time it is.

 
The winter months are when citrus crops really begin to shine.  I think my favourite thing about mid to late winter is seeing the New Zealand oranges begin to appear on the supermarket shelves (or at your local market, if you’re lucky).  These golden globes are like beacons of hope – “hang in there, spring is almost here!” they announce.  Their tart, bright flavour is just the thing to awaken jaded palates and I think citrus gives us the perfect example of why eating in season really is the way to go.  I eschew imported citrus at all costs – the look, smell and taste of imported oranges and lemons (be they either from the Northern Hemisphere or just across the ditch in Australia) has always been accompanied by a whiff of tired decay when met by my senses.  Lots of people complain that the New Zealand fruit is too sour – if your palate is used to less tang, just wait until later in the season, or try slicing a peeled orange into chunks and either drizzle it with runny honey or add a handful of raisins or dried cranberries.  Let’s support our local growers!
 
I’ve never actually had an orange tree to call my own, but one is definitely on my wish list.  When I still lived at home, the local conservation group in our area would have a bulk order of organic oranges shipped down from up north each winter.  A 20 kg carton kept my Mum and I, avid orange fans, well satisfied till the following season.  Orange trees are highly ornamental as well as useful on the culinary front – their glossy dark green foliage, highly scented blossom, general good looks and manageable growth habits make them an excellent choice for the home garden.   
      
Oranges: a short family history
Oranges belong to the Rutaceae, the rue or citrus family, along with their lemon, lime and grapefruit kin.  An orange in our everyday vernacular usually refers to the sweet orange, Citrus x sinensis, but amongst its stablemates, you will also find the sour orange (Citrus x aurantifolia, the sour/bitter or Seville orange, now mainly popular for marmalade production), Citrus aurantifolia var. bergamia (bergamot, which bears slightly pear-shaped fruit with highly aromatic peel, the oil from which is used to scent Earl Grey tea) and Poncirus trifoliata, trifoliate orange, a fiercely spiny number with three-lobed leaves, which is a common commercial rootstock for many citrus varieties.  If you’ve ever noticed vigorous shoots coming away at the base of a citrus tree in your garden, with foliage that looks nothing like the fruiting part of the plant, it’s likely you have a rootstock running rampant – cut these off before they take over!
 
Native to China, Northeast India and Southeast Asia, there is no actual ‘wild’ type orange, so the fruit as we know it was likely selected for domestication in one of these native regions.  It is a natural hybrid between the pumelo (Citrus maxima) and the mandarin (Citrus reticulata).  The earliest reference to oranges in Chinese literature dates from 2400 BC, with later mentions in Sanskrit in 800 BC.  From its native climes, the orange spread via trade routes to the Mediterranean by the 1400s, with the Spanish to South and Central America in the mid-1600s and was also widespread in Europe by this time.  Sweet oranges were considered a luxury fruit and the wealthy cultivated trees in large purpose-built conservatories known as orangeries.  They likely reached North America with the French when they landed in Louisiana.  King Louis XIV of France was a great fan of oranges and as a result, they were cultivated en masse, with a large-scale royal orangery built at the Palace of Versailles to ensure year-round supply.  
 
In modern times, oranges are now the most widely cultivated fruit worldwide and are an important commercial crop throughout the Mediterranean, the Far East, South Africa, Australasia, North and South America and parts of the Caribbean.  A significant proportion of the crop goes into juice production, the rest as fruit for fresh consumption, for preserves or for the production of essential oil from the skins.  The orange tree is particularly useful in that three distinct essential oils are produced from it: neroli, from the blossoms; petitgrain, from the foliage and sweet or bitter orange from the peels.  The latter is exceptionally useful as a natural insecticide and cleaning agent (I’d be lost without De-Solv-It® for removing sticky labels off jars and bottles) and terpenes extracted from the rind are also used to produce paint and resins.  Orange blossom water is a by-product of the bitter orange flower oil distillation process and is used to flavour cakes, beverages and desserts in a similar fashion to rosewater.  Oranges are famed for their vitamin C content, but most of it is contained in the peel and pith, which are not usually consumed.  Lesser known is the fruit’s folate content – the average orange contains approximately 20% of an adult’s RDI.  If your orange tree ever gets too old and decrepit, rest assured that its hard, yellow wood is useful for cabinet-making and woodturning.   
          
Which came first, the fruit or the colour?  For a bit of trivia that may be of use down the pub, the colour was named after the fruit, with the first recorded reference of orange as a colour name being from 1512.
 
Suitable climates and growing conditions
Oranges are subtropicals, and as such do not require winter chill to set fruit.  They crop well in warmer climates, but they do not tolerate very high temperatures.  Their low-temperature tolerance limit is -2 to -4°C, depending on age.  They will grow well throughout the North Island and produce into the upper South Island, provided they are planted in a sheltered position – basically, the further south you go, the greater the level of protection required.  Oranges can be container-grown successfully, as long as they are supplied with a growing media rich in organic matter, some fertiliser and adequate moisture – just make like King Louis and move your plant inside for the winter months.  You can expect grafted trees to produce a crop within two to three years, but as is usually the case, seedlings take longer to produce fruit (at least five and up to 10-15 years).  
 
Oranges are self-fertile, monoecious with hermaphrodite flowers, which are pollinated by insects.  This is excellent news as you are ensured a good crop with just one tree in the garden.  They are also interesting in that they produce seeds via the normal process of cross-pollination, giving rise to genetic variation in the offspring and also form seeds via the process of nucellar embryony, which effectively results in seedlings that are exact clones of the parent tree.  Not a fan of seeds in your citrus?  Some orange cultivars produce fruit even if they haven’t been pollinated, resulting in completely seedless fruit.  This handy mutation is called parthenocarpy and can occur naturally or be artificially induced.  It is a useful tool for modern fruit breeders keen to please ever-picky consumers!  It takes six to eight months for fruit formation from pollination to harvest, with the trees beginning to bloom again the following spring while there are still likely ripe fruit on the trees.  
 
Oranges can be propagated from seed, cuttings or by budding and grafting.  For the home garden, save yourself the fuss and purchase a grafted plant of the desired cultivar from a reputable nursery – that way you can also choose a rootstock to suit your climate and soil type.  For those that like to tinker, by sowing fresh seeds in the spring you have the advantage of genetic variability within seedlings and potentially additional hardiness and fruitfulness in the offspring.  Bear in mind that a reasonable proportion of seedlings will be nucellar (clones), usually differentiated by the speed of germination, which is faster than that of cross-pollinated seeds.  If you want to take cuttings, collect semi-hardwood material during summer.       
    
Site selection and planting
A site with full sun is ideal, but a semi-shade can also work.  Avoid exposed locations as orange trees do not tolerate wind.  The cultivar and rootstock also have an influence on overall hardiness, so choose a variety to suit your locale.  The most common commercial rootstock used for citrus in New Zealand is trifoliate orange, P. trifoliata, which suits our cooler climate.  ‘Flying Dragon’ is a slower-growing P. trifoliata mutation which confers dwarfing characteristics.  C. aurantium is sometimes used in fertile, well-drained soils and rough lemon (Citrus limon) is suitable for sandy soils in warm climates. 
 
Oranges are tolerant of a reasonably wide range of soil conditions, but as for most fruit crops, do best in fertile, deep soils with adequate drainage.  The heavier and wetter the soil type, the more likely your tree is to struggle.  Avoid waterlogged sites, as most of the tree’s roots go deep and exposure to waterlogging results in increased susceptibility to diseases such as Phytophthora root rot.  Avoid alkaline soils, as these can induce iron deficiency, which leads to interveinal chlorosis of the leaves.  Plant your tree during winter or early spring, favouring the latter if you live in a frost-prone district.  The planting hole should be wide enough to allow bare-rooted trees to have their roots spread without bending and allow a gap of 10 cm free space around the root ball of container-grown plants.  The soil surface level after planting should equal the depth of which the plant was growing in the nursery bed or planter bag/container.  The bud or graft union must be above soil level to prevent Phytophthora infection at the union.  Water the young tree in after planting so the soil settles around the roots.  Orange trees will reach around seven or eight metres at maturity, possibly higher if allowed.  If you are planting more than one, allow a between-tree spacing of five to seven metres.   
  
Culture and care
The moisture requirements of orange trees are highest in the spring and taper off again towards autumn.  Overwatering can result in disease issues and watery, insipid fruit that is pale in colour.  Drip irrigation close to the trunk is ideal – or a gently trickling hose.
Orange trees are heavy feeders.  During the establishment phase (years 1-3), allow 1-2 kg of a balanced general or specific citrus fertiliser, split into two applications (two-thirds in late winter/early spring and the remaining third in late summer) per year, spread around the tree’s dripline and watered in well.  Increase the amount applied by half a kilo each year until a maximum of 5 kg is reached at maturity.  You can also apply a layer of organic mulch out to the dripline in winter, but take care to avoid the area directly around the trunk. 
   
Pruning
Oranges are easy-care in terms of pruning, naturally taking on a tidy, compact shape.  In the early years, concentrate on shaping the tree, removing suckers from the rootstock and any particularly low-growing branches to achieve good ground clearance.  If you have a vigorous cultivar, thin out some of the branches to allow good airflow through the canopy and adequate light penetration to assist with fruit ripening.  After that, keep an eye out for the usual pruning candidates – dead, diseased or damaged wood.  Bear in mind that as an evergreen species, the orange stores the resources required for flower and fruit production in its leaves and if pruned too heavily, the yield will drop.  Carry out pruning in the winter months to avoid ingress by the lemon tree borer, 
Oemona hirta, which lays its eggs from October to January and has a penchant for freshly-cut wood.  Seal all pruning cuts immediately with a paint containing fungicide such as Yates Bacseal®.
 
Pests, diseases and what to do about them
Verrucosis (citrus scab) is a fungal disease, and while in terms of fruit production the damage is largely cosmetic, over time the infection can cause a decline in tree vigour, so if your tree is badly affected, you are best to treat it.  Brown rot, another fungal disease, can cause significant fruit loss, and its spores will overwinter in mummified fruit and in cankers on branches, so establish a good crop hygiene regime and remove these sources of inoculum from the tree as you find them during the growing season and again at pruning time when the main crop has been harvested.  Diseased plant material should be collected up and burned or disposed of with your household waste, not composted.  A copper spray timed to coincide with when the petals have fallen and fruitlet formation has taken place in late spring or early summer, and again in late autumn or early winter should take care of both of these diseases.
 
In terms of insect pests, orange trees are commonly affected by leafroller caterpillars, mealybugs, various scale insects and thrips.  An application of summer oil in February and again in May can assist with scale insects, while Yates Nature’s Way® Citrus, Ornamental and Vegie spray is an organic pyrethrum and oil combination spray that can be applied to combat thrips, mealybugs and leafrollers.  Follow the label directions.  Any sooty mould fungus that develops on fruit as a result of feeding by sucking insects is purely ornamental – just scrub the fruit with a nail brush and some soapy water after harvesting. 
    
Varieties: My top picks
The New Zealand orange harvest extends from approximately mid-June to late February.  Blood oranges were originally natural mutations of C. sinensis with varying levels of skin and flesh pigmentation, the degree of presence is affected by climatic conditions.  Many of the more recent cultivars are hybrids.  They often have a distinct flavour and are favoured for their aesthetic value and are widely utilised in specialty product lines including juices and desserts.  
 
Early season cultivars
 
Washington Navel – a major commercial strain worldwide, with large, well-flavoured fruit.  Ripens July-November. 
Navelina – early-ripening navel type (mid-June to September), bearing smooth-rinded, oval fruit which are seedless, juicy and sweet.
Tarocco – thin-skinned, medium-sized seedless blood orange, quoted to have the highest vitamin C content of all oranges, ripe from June to September.    
 
Mid-season cultivars   
 
Best’s Seedless – a New Zealand navel selection from Marlborough.  High yielding, bears semi-seedless fruit in the spring months.
Ruby Blood – semi-vigorous blood cultivar, produces small fruit with variably-mottled red skin and red-streaked flesh from September to November. 
 
Late-season cultivars
 
Valencia – a vigorous tree with good yields of medium-size, juicy, well-flavoured fruit.  Ripens November to February.   
Harwoods Late (sometimes Harward Late) – a New Zealand Valencia seedling, best-grown on P. trifoliata rootstock for good results.  Forms a large tree with high yields of thin-skinned, juicy fruit with good flavour. 
Moro – blood orange of medium size and vigour, productive, with a spreading growth habit.  The fruit is medium-sized, with few seeds and juicy flesh that is often well-pigmented and holds well on the tree.
 
What to do with your crop
Harvest your oranges when they are well-coloured as little ripening takes place after picking.  Taste test a fruit prior to harvesting any great quantity to make sure they really are ripe.  Use snips or secateurs instead of pulling the fruit off, to avoid damaging the branch or the peel of the fruit.  Cool winter temperatures enhance colour development in the skin – hence oranges grown in the tropics maintain their green skin colour, even when fully ripe.  Oranges are non-climacteric fruits, which means they do not ripen internally in the presence of ethylene after harvest, although this treatment can be used commercially to cause external ‘de-greening’ of the skin.
 
An orange tree in the garden means a steady supply of fresh juice, fruit for eating out of hand and flavourful rind for adding to baking, drinks and even savoury dishes – oranges work well with high-fat meats such as pork and duck, or try Nigel Slater’s Marmalade Chicken for a quick weeknight fix: Nigel Slater's midweek dinner: sticky spicy chicken drumsticks | Food | The Guardian
 
For out-of-season use, freeze squeezed and strained orange juice in cup portions or ice cube trays for free-flowing later.  For baking, grate the rind, mix it with some juice and freeze in ice cube trays as above.  With a little patience, you can even make your own candied peel for fruit cakes and Christmas baking – try a traditional boiling-in-sugar-syrup method or see Your Backyard Fruit Bowl: Beyond the Meyer Lemon for a cheat’s refrigerator method.  This article also contains a lemon squash recipe that you can substitute oranges for.
 
Here are two of my favourite orange-tinted recipes for you to try:
 
Orange curd
Adapted from a recipe by Nigel Slater
 
A twist on the traditional lemon curd – less tart, but in no way lacking in flavour.  Try a large spoonful with Greek yoghurt or a slice of chocolate cake.  Freezes well – spoon manageable amounts into plastic tubs and freeze for up to 12 months.  Defrost and store in the refrigerator and use within five days of thawing. 
 
Place 200 g granulated white sugar, 100 g butter (cut into cubes) and the zest and juice of three medium (preferably unsprayed) oranges into a glass or stainless steel mixing bowl and set it over a saucepan of simmering water on the stove.  Stir occasionally until the butter is melted.  Whisk four eggs together in a separate bowl, then add to the sugar/butter/orange mixture.  Whisk the mixtures together and let it all cook for approximately ten minutes, gently turning with the whisk until thick.  This is essentially custard made with fruit juice and butter instead of milk!  If storing in the fridge for immediate use, I like to sterilise a few glass jars (rinse in hot soapy water, place in the oven at 125°C for 30 minutes, remove and place on a wooden chopping board prior to filling, boil lacquered metal lids in a saucepan of water for ten minutes) and spoon the warm curd into these.  Seal.  If freezing, spoon into well-washed plastic pottles and seal. 
 
Orange liqueur
Adapted from a recipe by Peta Mathias
 
A handy stand-in for Cointreau, Triple Sec and the like.

Sterilise a 1-litre glass preserving jar with a screw-top lid using the method in the curd recipe above, but just briefly dip the lid in boiling water if it is plastic.  Remove jar from oven, place on a wooden chopping board, cover with a clean tea towel and allow to cool down.

Place 6 medium-size unsprayed oranges in a heatproof bowl, cover with boiling water and leave to stand for an hour.  

Place 200 g granulated white sugar and 350 ml water in a saucepan, bring to the boil, simmer for five minutes until sugar dissolves and forms a clear syrup.  Remove from heat and let it cool.  

Drain the oranges (the water you drain off will be beautifully scented – I’m always trying to think of a use for it rather than pouring it down the drain – cordial, poaching chicken…?) and remove the zest using a floating blade vegetable peeler.  Place zest in the sterilised preserving jar.  

Pour 700 ml vodka over the orange zest and then add the cooled sugar syrup.  Screw on the lid, shake well and store in a cool, dark place for one month, shaking daily for the first week.  

Sterilise some small bottles with metal screw-cap lids using the previous jar method, strain the liqueur through a tea strainer or small sieve set over a funnel into the prepared bottles and seal.  This will keep indefinitely in your grog cabinet.  It is an excellent addition to homemade ice cream and adds excellent flavour to bottled fruit, pairing especially well with plums and cherries. 

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/

 

Image credits

Orange grove – Hans Braxmeier, via Pixabay

Orange flowers and foliage – Pascal Bondis, via Pixabay

Orange fruit – Pixel2013, via Pixabay