HOW TO GROW CITRUS

Citrus are amongst the most popular and successful fruit trees for the home and garden.  The wide range available and their adaptability to many different climates ensures that they remain highly desirable.  Lemons are firm favourites and a must for every garden.  Their fruit is so useful in the kitchen and around the home.  Oranges, along with Mandarines and Tangerines also feature highly in many parts. 

Some of the lesser known citrus types are becoming more available, both as fruit and as ornamental garden plants.  Most citrus types can be grown as pot or container plants.  The larger the pot and the greater the volume of soil, the better the trees grow, perform and last.  Potted citrus is both productive and decorative in the landscape.

PLANTING PROCEDURE

  • Dig square planting holes one third deeper than the height of the nursery container and twice the width.
  • Add compost and superphosphate to the bottom of the dug hole at the recommended rates and mix them in with the soil.
  • Firm down the soil in the base of the hole to prevent post-planting subsidence.
  • Carefully remove the nursery pot or bag from the rootball of the tree and place the rootball into the hole.
  • The top of the rootball should be 2cm to 3cm above the surrounding soil level.
  • Fill in the soil around the rootball, firming down as the level rises, until it is level with the surrounds.
  • Create an irrigation basin with the remaining soil 30cm to 50cm away from the stem of the tree in a circle.  This prevents water from draining away.
  • Water in thoroughly, then check for further soil subsidence.  Top up soil if necessary.
  • Mulch around the tree, extending to the irrigation basin with pine bark or dry straw.
  • Check watering regularly to ensure that the young tree doesn’t dry out.
  • Insert a strong stake (wooden, bamboo or metal) next to the tree and tie the tree securely to the stake.
  • In extremely hot climates, young trees may need shade protection during summer to prevent sunburn to exposed stems.
  • Do not allow the soil to build up around the base of the stem.  
  • In cold climates, young trees may require protection from the winter frost.

FERTILISING AND CARE

  • Keep weed and lawn grass growth away from the citrus tree extending from the stem to the drip line (the imaginary line on the ground at the furthest edge of a tree’s canopy).  Surface roots are compromised by competing plant growth.
  • Maintain a mulch layer over the root zone.
  • Fertilise every 3 to 4 months with a balanced, blended plant food.  5:1:5 slow release nitrogen is recommended.  Apply at the recommended rate relative to the age and development of the tree.
  • Apply L.A.N. in early spring at the recommended rate.
  • Apply an annual application of Trelmix, either as a foliar spray or a soil drench in spring or summer.  This corrects trace element deficiencies.
  • Check plants regularly for rootstock re-growth (Rootstock is the base and root portion of grafted plant).  Cut out any rootstock growth immediately to prevent this from dominating the cultivated tree.
  • Citrus in pots or containers will need additional nutrition.  Use 2:1:2 water soluble plant food every 4 to 6 weeks for this purpose.
  • Citrus require little pruning.  Any growth that may cause the tree to look unbalanced or misshapen should be cut back.  Old, unproductive trees can be pruned back hard to rejuvenate them.

PESTS AND DISEASES

  • Check stems, branches and leaves for citrus scale – tiny red to brown flaky insects.
  • Citrus psylla causes bumps on the upper surface of leaves.  Trees need to be sprayed with an insecticide when new leaf growth emerges.
  • Aphids are often found on new growth tips.
  • Poor drainage around the root zone can result in phytophthora, or root rot disease.  This is often detected by dead patches of bark on the stem or trunk close to the ground, exuding a gummy sap.
  • Black sooty mould occurs on leaves where honeydew is prevalent.  It’s usually secreted by aphids.  Treat the insect infestation.
  • Orange dog caterpillars feed on the leaves and can be damaging to young trees.
  • For further information and advice, call in at your nearest Blackwood’s.

GARDEN USES

  • Plant citrus in fruit orchards or kitchen gardens
  • They are attractive in ornamental landscapes
  • Useful evergreen hedges – especially kumquats or Bearr’s limes
  • Great in pots or large containers, especially in formal garden styles
  • Fragrant blossoms enhance the garden ambience.

SUMMARY

  1. Citrus are relatively easy to grow in most areas, except the coldest, frosty parts
  2. Well drained soil is vitally important for growing citrus
  3. Full day sunshine on the north or west facing aspects is ideal
  4. Adhere to an annual fertilising programme
  5. Check for pests and diseases regularly

SHOPPING LIST

  • Tools for preparing planting hold
  • Pots or containers if needed
  • Selected citrus plants
  • Mulch for soil surface
  • Compost and superphosphate
  • Potting soil or growing medium
  • Stake for tying the young tree
  • Water or irrigation equipment