I once read a survey in an Australian landscaping magazine that listed the top five things you could expect to find in the average Aussie backyard – they were: a barbecue; a Hill’s Hoist (washing line); a dunny (outside toilet); a dog and a lemon tree – that’s a couple of living things and only one of them in the ground!

It tells you a lot about Australians and their way of life – and that, generally,  gardening was not top of their list!

One of the upsides of the recent COVID pandemic is that more people are getting out there and growing something. 

I am, however, fortunate that my life as a horticulturist has been full of gardens and enthusiastic gardeners, and their passion for citrus trees is evident .  Citrus are always top of the clients’ ‘must have’ list and questions about citrus, over the past forty years, have always outnumbered any other gardening questions.

LET’S START AT THE BEGINNING – PLANTING:

We are at the start of citrus fruiting season – autumn and winter – and just about every variety imaginable grows in my area – but to have healthy, productive trees a few simple guidelines should be followed right from the start.

CITRUS TREES NEED FEEDING –  it stands to reason really for they do a lot in a season – put on large flushes of new leaves, a heady covering of gorgeously fragrant flowers and, if you have cared for them, a bumper crop of delicious, juicy fruit – they are very busy little trees.  The nurturing of citrus pays great dividends and I couldn’t put it better than Jackie French, one of my favourite gardening authors, in her book Organic Gardening in Australia (1986).

“When we first came here (Braidwood, in the Southern Highlands of NSW) we inherited about twenty old citrus trees.  They were buried in ink weed and blackberry, had been rubbed to bits by cattle and were totally defoliated except for a few yellow leaves.

Ten years later, we’ve lost two of them, but the others are dark green, bushy and good bearers.

To cure our trees we mulched them to the drip line about half a metre high, using old lucerne hay, hen manure, stable sweepings and old sawdust.  The first lot took nearly nine months to rot down.  Then, as the soil became more active we mulched heavily three times a year, with organic matter and nitrogen rich additions (like chook poo and urine).

The first year there were more yellow leaves.  The second there were some tiny fruit.  After about five years the trees were green and healthy and the fruit reached its maximum size” 

• Pick a healthy tree – one that is disease free and a healthy looking.  Also check that it is not root bound and that the graft area is firm and healthy (all citrus are grafted – a top bit is grown onto a different bottom bit).  Choose the right variety for your area.  I use a lemon just about everyday and realized, very early on, that even on my small suburban block that I needed two lemon trees – in fact, I have three if you count the Lemonade.  In the subtropics the best varieties of lemon are Eureka and Villafranca (almost thornless).  The Meyer does well too, but I am not fond of it’s less than lemony flavour – it’s almost perfumed skin and juice are a result of it being a cross between a lemon and a mandarin.
• Choose an open, sunny position, preferably north to northeast facing, with shelter from strong winds. Plant in late winter to early spring.  Choose the right variety for your area. (Check with your local specialist nursery for appropriate species.) 
• A fertile, well-drained soil with a pH between 5.5-6.5 – which is slightly acid – is what they prefer. Citrus are vulnerable to root-rot so care must be taken to avoid badly drained areas. Checking the pH of the soil is important so it can be corrected, if necessary, before planting. (see UNDERSTANDING SOILS PAGE)
• The planting hole should be just a little deeper than the plant but twice as wide.  Do not put fertilizer in the planting hole – this will burn the roots.

FEEDING:

• Citrus trees are very hungry feeders and will benefit from a tri-annual complete soil fertiliser in autumn, winter and spring.   Always water the tree well after fertilising. Never place non liquid fertiliser close to the trunk or in heaps, spread it as evenly as possible to just past the drip-line of the tree. Compost or animal manures are ideal or a pelleted fertilizer available from most garden stores – like Organic Life or Dynamic Lifter.  Make sure you mulch after fertilizing.

• . A regular foliar spray (liquid fertiliser applied directly to the leaves) with a seaweed based fertiliser will go a long way to keeping your citrus healthy by providing the essential macronutrients of nitrogen, phosphorus and potassium + trace elements. SEE Making Your Own COMPOST TEA.  A foliar spray also has the added benefit of being immediately taken up by the plant and is a fantastic way to increase the plants resistance to pest and diseases.  This can be done monthly.
   

TOP TIP.  Don’t overfeed with NITROGEN rich fertilizers – you will end up with lots of leaves and little fruit.

My lemonade tree after feeding it for a year – it’s worth it!

WATERING: Citrus are thirsty plants.

• If you neglect to water them during dry periods the fruit will also be dry.
• Continual water stress leaves the tree weakened and less productive.
• Citrus need regular watering from flower bud formation through to fruit set to retain a good crop. Water stress is usually the cause of fruit drop.  Mulching will alleviate this.

MULCHING: Do not plant citrus (or any tree) in the middle of a lawn without having a grass-free mulched area out to the edge of the canopy.  Use whatever you can get hold of – thick straw, spent sugar cane and coarse wood chips are good.

• Grass and weeds compete with your tree for water and nutrients – if left to grow  under the tree they also encourage collar rot of the trunk.
• Grass around trees also equals the dreaded whipper-snipper!  I have seen more young trees damaged and ring-barked by thoughtless ‘whipping’ than I have had hot dinners!
• Wet newspaper, at least 10 sheets thick, can be used to kill weeds and grass under the tree and then topped with mulch regularly to prevent weeds returning.
• Always mulch past the drip-line of the tree as this is the area where most of the feeder roots are found.

TOP TIPS:  A lot of folk have problems with brush turkeys and say that they are reluctant to mulch under trees for this reason – the critters just dig it up.  A way to overcome this is by planting a green manure crop in the mulch (they put back into the soil as well as anchoring the mulch) with something like nasturtium – non-invasive, hardy and very pretty.

HOW TO SPOT COMMON NUTRIENT DEFICIENCIES IN CITRUS

IRON – a common deficiency in citrus with dieback of the new growth and intra-veinal mottling of the leaves.  If you are feeding regularly you may need to do a pH test to check the acidity/alkalinity levels as the iron in the soil can become unavailable if the pH is out of kilter.  Citrus prefer slightly acid soils of 5.5-6.5.  If the pH is OK, correct the iron deficiency with chelated iron diluted in water (rate on packet).

TOP TIP:  Iron deficiency in citrus acts like an early warning system for the rest of your food garden.  If your citrus look like this then it’s a good indicator that all of your garden probably needs a feed.

 

 

Iron deficiency of citrus leaves

 

 

NITROGEN – Overall pale yellow leaves and lack of vigour.  This is not to be mistaken for ‘winter yellowing’ where some of the leaves will turn yellow in the winter because the nitrogen in the soil is unavailable to the plant in cold and dry soils.  The leaves will turn green again with the spring rains.

 

 

Nitrogen deficiency of citrus

 

ZINC– Yellow tipping of leaves.

 

COPPER – Dieback and dry patches inside fruit.

 

MANGANESE – Intra-veinal mottling and lumpiness of leaves

 

MAGNESIUM – Very common and similar in look to iron deficiency ending up with a triangular patch of green at the base of the leaves leaving the rest yellow.  This can be fixed simply with a dose of Epsom Salts (magnesium sulphate)

 

 

 

• Choose an open and sunny spot to plant them – out of the wind.
• Mulch out to the drip-line.
• Feed regularly – not forgetting the essential trace elements.
• Prune to shape regularly.
• Ensure they are getting adequate water – particularly when the fruit is setting – dry plants mean dry fruit.
• Enjoy the beautiful flowers and perfume in the springtime.