Winter-flowering Winter-flowering

12 Introduction
flower in the winter months by default. This includes both plants that flower
over a long period, which may extend into early winter, and those that come
from other parts of the world, such as the grevilleas and wattles, which flower
during our winter (their summer). True winter-flowering shrubs, however,
flower in response to reduced light levels and, more importantly, a period of cold
or vernalisation (vernal is derived from the Greek word meaning “spring”); it is
this exposure to cold that triggers their flowering patterns.
Why Do Plants Flower in Winter?
Many processes, including age, circadian rhythms, vernalisation, and photo-
periodism, are necessary to induce plants to flower. Many of these complicated
cycles and processes are not yet fully understood.
Even in the harshest
weather, there is
something to see in the
winter garden.
All plants undergo a period of adolescence or juvenility before they become
sexually active and flower. In some cases, as is common with many short-lived
perennials and shrubs, this may take only a few years; certain trees, however,
including some groups of magnolias, may remain in their juvenile stage for
twenty to thirty years before they begin to flower. Luckily for us very few winter-
flowering plants fall into this group. If we were to raise new plants from seed,
they may only take three to five years to flower, but most of the plants we buy
from our garden centres or nurseries will have been asexually propagated