Having
returned
from
garden
visits
this
summer
to
places
such
as
Portland,
Vancouver
and
England,
I feel
compelled
to
write
about
a
common
frustration
of the
weekend
gardener:
zones.
It's
hard
to
pick
up a
seed
packet,
read a
plant
tag or
browse
a
garden
article
without
being
a
victim
of
"zone"
talk.
"Hardy
to
7B,"
"Grows
in 8,
9,
12-24,"
"Heat
Zones
7-9,"
"Perennial
in
Zones
21-24,
annual
elsewhere,"
etc.
Palm
trees
do
grow
in
Vancouver.
Bananas
are
regular
components
of
gardens
in
London.
Lilacs
and
redwoods
do
grow
in
Orange
County.
Nonetheless,
gardeners
in
Orange
County
can't
grow a
decent
peony,
lily
of the
valley
or
aspen
tree.
Don't
zones
have
something
to do
with
this?
In
1960,
the
U.S.
Department
of
Agriculture
published
its
first
zone
map. A
few
years
later,
it was
significantly
revised.
In
1990,
in
cooperation
with
the
National
Arboretum,
the
USDA
updated
its
zones
again.
The
USDA
uses a
one-to-11
numbering
system,
which
is
further
divided
into
A's
and
Bs.
In
1967,
after
30
years
of
publication,
"Sunset
Western
Garden
Book"
introduced
its
own
plant
zone
system.
Likewise,
"Sunset's"
zones
have
been
revised
several
times,
essentially
every
time a
new
edition
is
published.
Sunset's
zones
are
numbered
from
one to
24,
but
recently
five
more
zones
were
added
to
cover
Alaska
and
Hawaii.
Are
you
confused
yet?
The
point
of all
this
zone
stuff
is
supposed
to let
you
know
what
plants
you
can
grow
in
your
yard
and
which
ones
you
can't.
It's a
simplistic
shortcut
to a
complex
topic.
Gardeners,
like
most
people,
like
simple,
straightforward,
black-and-white
answers.
Here's
another
overly
simplistic
shortcut
— a
15-30-15
fertilizer
is a
better
value
than a
5-10-5
fertilizer,
right?
Not
necessarily.
At
best,
plant
zones
are a
guide.
Probably,
everyone
reading
this
column
is,
according
to the
USDA,
gardening
in
zone
10A or
10B.
If
you're
a
"Sunset"
reader,
you're
almost
all
gardening
in
zone
24.
This
is
certainly
true
of the
communities
of
Huntington
Beach,
Costa
Mesa,
Newport
Beach
and
Corona
del
Mar. A
handful
of
residents
in the
canyon
bottoms
of
Newport
Coast
might
drift
into
zone
23 or
even
22.
Now
that
you
know
your
USDA
and
"Sunset"
zone,
plant
selection
will
be
simple,
right?
Not
exactly.
Consider
this:
Orange
County
shares
the
same
latitude
as
Lubbock,
Texas,
or
Charleston,
S.C.
Surprisingly,
we
share
the
same
plant
zone
as
Orlando,
Fla.,
whose
latitude
is 10
degrees
less
and is
almost
500
miles
farther
south.
In
addition,
Orange
County
receives
no
summer
rain,
while
summer
is the
wettest
time
of the
year
in
Orlando.
Are
Orlando
gardens
and
Orange
County
gardens
really
that
much
the
same?
Consider
that
Orange
County
gets
only
13
inches
of
rain
per
year,
while
Orlando
receives
a
torrential
60
inches
each
year.
You
are
beginning
to see
a few
of the
problems
with
plant
zones.
It
gets
worse.
One of
the
biggest
factors
affecting
plants
is
summer
heat.
Many
plants
from
the
north
are
not
able
to
handle
Southern
California's
hot
summers.
Also
nighttime
heat
and
humidity,
not
just
during
the
day,
has a
significant
effect
on the
suitability
of
many
plants
for
local
gardens.
Compounding
the
situation
even
further,
the
fluctuation
between
night
and
day
temperatures,
in
many
cases,
also
affects
plant
health.
During
the
day,
plants
store
up
energy.
If
nights
are
cool,
this
energy
goes
into
the
growth
of the
plant.
But if
the
nights
are
too
warm,
this
stored
energy
is
lost.
Now
let's
introduce
another
factor:
heat
dormancy.
Hostas,
for
example,
will
usually
decline
in
USDA
zones
9 and
10 and
"Sunset"
zones
21
through
24.
Our
problem
is
that
temperatures
do not
drop
far
enough
in the
winter
for a
hosta
to go
completely
dormant.
Hostas,
like
many
other
plants,
need a
dormant
period
at a
specific
temperature
in
order
to
start
growth
again
in the
spring.
In
summary,
whichever
zone
system
you
follow,
use it
only
as a
guide,
not a
rule.
Many
factors
are at
play
when
deciding
whether
a
plant
will
be a
good
choice
for a
garden.
Yes,
our
gardens
are in
USDA
zone
10 and
"Sunset"
zone
24,
but
don't
stop
there.
There's
much
more
to
know
before
deciding
whether
a
plant
will
grow
well
in
your
garden.
After
all,
remember
that
gardeners
are
like
doctors:
They
bury
their
mistakes.
RON
VANDERHOFF
is the
Nursery
Manager
at
Roger's
Gardens,
Corona
del
Mar.
ASK
RON
My
Western
garden
book
does
not
address
how to
handle
a
divided
clivia.
Cut
leaves
back?
How
much?
Prune
roots
lightly?
Heavily?
What
type
of
soil
and
any
soil
additives?
There
is
very
little
soil
remaining
in the
pots,
mostly
roots.
(It
was
largely
adobe
originally.)
Thank
you
for
your
help.
BARBARA
Newport
Beach
I have
found
clivia
very
easy
to
divide
and
replant.
Once
the
clump
is dug
up,
the
individual
divisions
can be
broken
apart
from
one
another
by
hand,
even
when
rather
small.
Knock
off
most
of the
soil;
rinsing
the
roots
with
water
works
well
for
me.
Leave
the
attached
roots
intact,
only
removing
dead,
broken
or
decaying
parts.
Remove
any
dead,
brown
leaves;
otherwise
do not
cut
back
the
leaves.
Allow
the
divisions
to
air-dry
in a
shady
spot
for a
few
days.
Clivia
like
an
organic,
slightly
acidic
soil,
so mix
in
liberal
quantities
of a
quality
planting
mix,
as
well
as
some
acidic
azalea-camellia
mix.
After
replanting,
keep
the
area
dry
for
another
week,
then
add
water
sparingly.
In
Orange
County,
clivia
can be
divided
any
month
of the
year,
but
fall
or
spring
is
probably
best.
