Conventional wisdom
dictates that a cold climate is necessary to grow apples. Most charts
will list apples as needing 800-1000 chilling hours to fruit, chilling
hours defined as the hours the temperature is between 32 and 45 degrees
Fahrenheit, with temperatures above 45 being deductive and below 32 not
counting. Chilling hours are said to be needed to re-set the biological
clock of the tree to blossom and fruit; without this the tree will
blossom and leaf late or sporadically.
Riverside, Southern
California is a city known for citrus, not apples, and we have the
parent Washington Navel Orange tree and the UCR Citrus Experiment
Station. It has hot summers; warm winters, and averages about 10 inches
of rain a year (last year we got 2 inches). We receive 400 chilling
hours on a good year, but often less than that. The conventional wisdom
on chilling hours means that the only apples suitable for our climate
are a few select “low-chill” apples like Anna, Dorsett Golden, and Ein
Sheimer, all of which require less than 400 chilling hours. Most other
apple varieties are unsuitable and will not fruit or produce good
quality. The only problem with this is that somebody forgot to tell the
apples.
Two years ago I
planted 100 varieties of apples as benchgrafts in order to test this
theory. More than half of them fruited for the first time this year,
and we were able to see which varieties were suited to our climate. The
first thing I can say is that the chilling hour theory for apples is
wrong. On the other hand, I’m afraid the chilling hour theory is all
too true for stone fruit, and if you plant a variety with a too high of
chilling hour listing, you will get a nice shade tree but no fruit.
Two good examples
that debunk the chilling hour theory are Pink Lady and Granny Smith. In
our climate, they never do completely lose their leaves. They slow down
a bit in the winter, but still occasionally blossom in November and
December and even start to grow a tiny apple (which I pick off). In the
spring the new leaves just push out the old ones, and they blossom and
fruit just fine. This leads me and others to believe the impetuous to
fruit may be more tied to day length than chilling hours.
Chilling hours do
have some affect on the tree’s growth habit, with a colder climate
usually resulting in a more compact bloom period on many varieties.
Some apples clearly weren’t happy here (not that I really want them to
be happy) and showed symptoms of lack of chill. Bare wood with no
leaves on the branches near the trunk was the most common symptom, as
was delayed and prolonged blossoming; but neither of these turned out to
be a good reason not to grow that variety. For instance, Arkansas Black
had lots of bare wood by the trunk, but tufts of leaves and at least two
or three apples on each branch tip, about the same productivity as in
our mountain regions. Hawaii had such a strung-out bloom that we
harvested the first apple in August and the last one in November. But
the quality of the apples was good the entire time, so is this a bad
thing?
A strung-out
blossom period in a colder climate would be disaster, exposing the tree
to late frosts and fireblight strikes repeatedly. But in our warm and
dry climate, it just means you get an apple variety over a longer
period, with ripe apples on one tree or another for seven to eight
months. Delayed blossoming also works out in our favor; it just means
the apple will ripen in late November, when our climate matches that of
Central Washington in early October and colors the apples up
beautifully. We do not have to worry about the length of the season, as
the apples can hang on the tree into January if they want.
Some trees have
also showed the ability to adapt to our climate. When I first planted
two Fujis side-by-side, they didn’t blossom until Anna was ready to pick
in late June. But every year they’ve been blossoming a month earlier
and the bloom has become more compact until now they fully blossom and
leaf out in mid-April. They also afforded me the opportunity to test
the theory that stripping leaves by hand in winter helps re-set the
clock. I stripped one in mid-December and the other dropped its leaves
late January. They budded within 5 days of each other, showing minimal
benefit.
Some have suggested
that I actually have a colder “microclimate” with low spots or
topography that helps to satisfy the chilling hours. This is nonsense,
as I tore out a big clump of bananas to plant part of the orchard, and
the neighbors Navel Orange Tree is right next to it. Avocados, olives,
loquats, mangos, guavas, and cherimoyas are the typical tree fruits and
our roses bloom year-round. This is a warm Mediterranean climate and
the only explanation is that most apples will grow just fine in a warm
Mediterranean climate.
The warm climate
does mess with the ripening times, and pollination and harvest charts go
out the window. Rome Beauty ripened in late August; Yellow Transparent
ripened three weeks later in September. We still have a dozen varieties
on the trees for Thanksgiving and a few will be there for Christmas.
Dorsett Golden and Anna will blossom in late January.
It is not a
question of which apples will grow here, but which ones are best suited
to our climate, the same question facing the rest of the country. Our
brutal summers with 115 degree heat weeds out some varieties; Ginger
Gold turned to mush and Braeburn rotted on the tree. We nicknamed
Maiden Blush “Maiden Mush” and Snow was more like “Slush” (all of these
fruited heavily by the way). But for every failure we had five success
stories. Hawaii and Williams’ Pride were our favorite late summer
apples, staying firm, crisp, sweet and juicy while ripening in the worst
heat. Wealthy showed us why it is popular for growing in the tropics,
as it was wonderful and spicy. A Swiss Cox cross named Rubinette
claimed the overall title, with a crisp, sweet/tart, complex flavor that
begged for another bite. The half-dozen varieties each of sweet
crabapples and russets did well, with Zabergau being our favorite
russet. 90% of our tested varieties are far, far better than anything
we can get from the store.
But as fall turns
to winter some late-ripening apples rise above the rest and show that
our climate is where they become world class. When grown in the local
mountains, Arkansas Black is denigrated as being rock-hard, tart, and
mediocre until they soften up a month or so off the tree. But when
picked here at Thanksgiving, right off the tree the beautifully-colored
Arkansas Black has wonderfully crisp, deep yellow flesh with a sweet,
dark, winey flavor with strong hints of cinnamon; much better than the
mountain ones. I suspect they will not keep as well, but no matter as
we will soon eat them all. I also never realized how green the Fujis in
the supermarket are until I tasted a truly ripe one; they have a
yellowish-orange flesh and much more complex flavor. Pink Lady grown in
our climate might as well be a different variety than those grown in the
Pacific Northwest as there is no comparison. Arkansas Black and Pink
Lady have also shown themselves to be impervious to heat, doing just as
well in the blast furnace of Las Vegas, Palm Springs, and Phoenix.
A wholesale nursery
salesman and I were discussing how it became so widely considered that
Southern California was unsuitable for growing apples, as we both have
found evidence that apples were once more widely cultivated here up
until the 1930’s. We speculate that small farms could not compete with
Washington State conglomerates with either quantity or color, and the
strung-out harvest times would be very undesirable for a commercial
grower. Since university programs tailor their advice to commercial
agriculture, perhaps the suitability for home gardeners was not
addressed.
Overall apples are
not much trouble to grow in Southern California, or else I’d never be
able to keep up with the orchard. Even after testing only a fraction of
the available varieties, we’ve shown that you can have outstanding
apples for most of the year and pretty much ignore the chilling hours
when choosing the varieties. We realize that one year’s testing cannot
be conclusive for ruling out varieties, as some apples may have just had
a bad year like they can everywhere. But there’s no reason Los Angelus,
San Diego, and even Palm Springs cannot be considered “Apple Country”.
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