Seed Guide 2007 pgs 01/41 - McKenzie Seeds

G R O W I N G I N F O R M A T I O N
year or more has passed, so never be too
hasty in discarding a seed container.
Pre-chilling was traditionally done by
standing the pots outside in a cold frame
during the winter. It is often quicker to
adopt the following technique using a
domestic refrigerator and this is of
particular value if you obtain your seed
outside the winter months.
To pre-chill, first sow the seed on
moistened seed compost, seal the seed
container inside a polythene bag and
leave at 60-65F (15- 18C) for 3 days then
place in a refrigerator for the
recommended period. For convenience
large seeds can be mixed with 2-3 times
their volume of damp seed compost,
placed direct into a polythene bag which
is sealed and placed in the refrigerator.
However; there must always be sufficient
air inside the bag and the compost
should NEVER become either too dry or
over wet, After pre-chilling these seeds
can then be spread with the compost on
top of a seed container and firmed down.
The seeds must be moist whilst being prechilled,
but it will harm them if they are
actually in water. During the period in
the refrigerator; examine the seeds once
a week and remove all the seeds into the
specified warm conditions if any of them
start to germinate.
Light also seems to be beneficial after
pre- chilling, so pre-chilled seeds should
have only the lightest covering of
compost, if any is required, and the seed
trays or pots, should be in the light and
not covered in paper.
Double dormancy
Some seeds have a combination of
dormancies and each one has to be
broken in turn and in the right sequence
6
before germination can take place; for
example some Lillies, Tree paeonies,
Daphne etc need a warm period during
which the root develops followed by a
cold period to break dormancy of the
shoots, before the seedling actually
emerges. Some seeds need a cold period
followed by a warm period and then
another cold period before they will
germinate. In all cases the times and
temperatures have been provided in the
sowing instructions.
Outdoor treatment
The above mentioned methods accelerate
the germination process and help to
prevent seeds being lost due to external
hazards (mice, disease etc) but outdoor
sowing is just as effective except longer.
The seeds are best sown in containers of
free draining compost and placed in a
cold frame or plunged up to their rim
outdoors in a shaded part of the garden,
preferably on the north side of the house
avoiding cold dry winds and strong sun.
Recent tests show that much of the
beneficial effects of pre-chilling are lost if
the seed is not exposed to light
immediately afterwards. We therefore
recommend sowing the seeds very close
to the surface of the soil and covering
the container with a sheet of glass. An
alternative method especially with larger
seeds, is to sow the seed in well prepared
ground, cover with a jam jar and press
this down well into the soil so that the
seeds are enclosed and safe from
predators, drying out etc.
Sowing
Where outdoor sowing is recommended
moist soil which is weed free and has
been raked down to a fine tilth is
essential. For hardy annuals and
perennials sowing can be carried out
from late winter onwards as soon as the
ground is workable and has warmed up;
half hardy annuals after all danger of
frost is passed and when the soil has
warmed up.