PA256833 s Pandrea


Encouraging new plants to extend their root-ball

The potting mix in most plant pots is very light, with many large spaces created by the sand/pine fines used. It also needs to be watered often as it drains rapidly. This is nothing like the soil in most new gardens, especially in Canberra where it is tightly packed (dense) clay and very dry after the drought.

When you plant a new plant, you need to encourage the roots to spread out of the original root-ball shape of the pot and extend into the surrounding dry hard ground.

Some ways of achieving this are:

  • Fill the planting hole with water, and let the water drain away into the soil before planting. Do this twice. This stops dry ground from sucking the water from your new plant's root-ball, as well as providing moisture for the new roots to find.
  • Make the back-fill soil into an introductory zone to the garden soil. This zone should have properties intermediate between the potting mix and the garden soil. The back-fill soil will be less dense than the surrounding soil because quite a lot of air will have been included through the digging process. A little added humus at a ratio of 1 humus to 5 back-fill soil would be beneficial. If you have no compost, then some coconut peat soaked in water is suitable. The new roots will then encounter a 'softer' soil with more air pockets and some water-retaining humus.
  • Add an inorganic, rock chip or pebble mulch from the trunk to about 15cm out from the plant, to prevent water loss and to shade the root area. Do this even if the garden bed has an organic all-over mulch. The new plants should enjoy your attention to detail, and thrive.

[Jan Simpson]