Pot or Root Bound: Australian native plants have adapted to surviving and thriving in a dry environment where rainfall is often sparse and the soil is sandy and well-drained.
When native seeds germinate their taproots grow down rapidly in order to reach sub-soil moisture. When grown in pots the taproot still develops rapidly and hits the base of the pot where it proceeds to grow around the circumference. If left too long then the roots will literally tie themselves in knots. These plants are pot or root bound and this condition is virtually horticultural constipation.
Drastic surgery is required on these twisted roots when planting. Sometimes plants do not survive this drastic surgery. If the roots are left without surgery then usually the plant will expire suddenly some time down the track.
The native plants prone to constipation are those grown from seed and include Acacias, Casuarinas, Eucalypts and Hakeas. Seed grown natives should be planted as tube stock. They are ready for planting when roots appear at the base of the tube.
Plants grown from cuttings are less prone to horticultural constipation as they develop a fibrous root system with no tap root.
Sometimes plants are initially grown in small, 50 millimetre thumb pots before potting on into larger pots for sale. If these plants are pot bound in the thumb pots then only a few roots will make their way into the soil of the larger pot. The days, of these plants, are frequently numbered.
The photograph shows the root system of a plant that expired suddenly in one of our gardens. This plant was purchased in a large pot. An autopsy revealed that the root system was almost totally confined to the area of the initial thumb pot. Fortunately cuttings had been struck, from this plant, before its expiration.
All the plants we propagate are potted on into tubes and then planted. Tube stock plants do look rather small when compared to advanced plants in large pots. In the long term tube stock grows faster and has a much higher survival rate than their advanced and more expensive cousins.