ON THE PLOT
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experience the first frost
around 19 May and 80% of
the province will have frost by
1 June.
In terms of the last days of
frost, 20% will have the last
frost on 15 August, while 80%
of the province will have the
last frosts by 3 September.
These are of course averages
and used as a guideline, for
frost is notoriously erratic.
There are other factors within
your property that will also
affect your choice of planting.
There can be a noticeable
temperature variation within a
few hundred metres in most
areas of Gauteng.
The cold collects in valleys
and depr essions. If your
smallholding is in a flat area, it
means your land is more
exposed to cold winds in
winter.
If there a number of buildings
on your or your neighbour's
plot, you may be sheltered
from cold winds or the
buildings may channel the
exposed surfaces, such as
foliage and lawn, forming
dew.
When temperatures drop to
below freezing, the water
vapour changes the ice
crystals, which is known as
frost.
In winter, frost is most likely
to occur on wind-free,
cloudless nights as both wind
and cloud cover can keep the
air temperature warmer.
In some regions the air is too
dry for ice crystals to form.
Nevertheless the belowfreezing temperatures
Plants covered with lightweight frost cloth.
wind into your garden.
so that you can feel where the damage plant structure and
such frosts are known as
cold collects, where it flows
There will also be temperablack frosts, so-called because
ture variation within different and where it is warmer and
of the colour of the damaged
more protected.
parts of your smallholding.
plant foliage and stems.
These 'zones' can change over Knowing this will enable you
Frost damage occurs when
time as buildings and plants
to better plan where to plant
the cell sap in plants freezes.
within and surrounding your
hardy plants to screen your
This causes the sap to expand
land change.
garden and veggie patch.
and the cell walls rupture,
One way to find the cold
What actually happens to
thereby destroying the plant.
areas in your property is to
cause frost? During the night
Some plants cannot survive
walk around your garden very both the soil surface and the
frost – these are commonly
early on a cold morning,
air cools, until water vapour
Continued on page 27
preferably dressed minimally, in the air condenses on
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