The soil performs three basic functions for plants:
- The soil should give the plants a chance to root down and hold firm.
In cultivation, this means the soil must not be too dense and prevent
the roots penetrating. Furthermore, the soil must be well-drained
so that surplus water can run away and so avoid root rot.
- The soil needs hold a certain amount of moisture for use by the
- Finally the soil should provide the plants with necessary nutrients
for the growing season. Plants in pots rapidly exhaust the soil and
need regular feeding or repotting when required.
After repotting, plants get all the nutrients they need
from the new soil, but they soon use them up and need feeding. There are
two main groups of fertilizer which differ in content. The so-called complete
fertilizers contain nitrogen (N), phosphates (P) and potash (K). It is
preferable to choose fertilizers with a low nitrogen content, but as the
composition of all fertilizers varies considerably, it is best to vary
the brand from time to time to avoid a deficiency of any particular component.
Complete fertilizers also contain trace elements besides the normal components.
These are required by plants, but with sufficient use of complete fertilizers
and regular repotting, it is rarely necessary to use special fertilizers
with these trace elements. However if you feel the need to use trace elements,
please carefully follow the instructions, as an overdose can kill the
plants. During the growing season regular but light fertilizing is recommended.
Repotting small or slow-growing species is not necessary every year. Faster-growing
species, however, can exhaust the soil after a year, despite regular feeding,
although increasing the dose can delay the necessity to repot. However
the danger of this system is that the plants can become torpid and susceptible