GROW FOOD slow food Have your garden and eat it too. A practical guide to organic gardening in the sub-tropics with step-by-step instructions and delicious seasonal recipes. Come with me too on some of my travels in Australia, Europe, Asia and beyond.

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 is not top of their list!  However, I’m fortunate that my life as a horticulturist in Australia 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.

  • 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 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: If you feed your citrus regularly they will be healthier, more resistant to pest and disease attack and bear more fruit.

 
  • 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)
 
In previous posts about citrus I have discussed caterpillars on citrus and how to deal with common pests (scale, sooty mould and aphids).
 
 
 
 
 
A NOTE ABOUT CITRUS IN POTS:  Citrus have always made fantastic pot plants and have been grown this way for hundreds of years with large greenhouse conservatories or ‘orangeries’ a part of a lot of the stately homes of Europe, where the potted citrus would be wheeled inside to overwinter.
 
The roots of citrus in pots cannot go foraging for water and nutrients and require particular attention to keep them looking as healthy as the orange tree in the above photo.  Enough water, but not too much and the right kind of food, but not too much – and don’t forget to foliar spray with liquid seaweed, compost tea or worm juice.
 
 
 
TO SUM UP CITRUS
 
  • 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.