Evening star., 1951-08-26
Hardness in Plants
Term Embodies Several Foctors Including
Health, AccIimotizotion and Protection
By w. n. Younomon

oun9muH
hardness Of plants that is most
commonly overlooked Is the i'm
portance of keeping q plant
Thousands Of rose bushes,
weakened by blackspot. are lost
each winter and the loss Is usually
blamed on the weather. rather
than upon the weakness Of the
plants. Healthy plants of rasp-
berries will survive our winters
without loss but most paintings,
weakened by disease, have heavy
mortality.
Feeding our shrubs, If carelessly
done, Is another factor contribute
ing to winter injury blamed on
the lack Of hardness. The box
wood, If fertilized during the sum-
mer, does not have time for the
new growth to properly mature
before freezing weather. II the
feeding were done ct the proper
season-January to March-the
wood has time to mature. The
same applies to feeding roses. No
fertilizer after the first Of August
is the standard recommendation.
However, there are seasons when
roses escape injury, although fer
tilted in August. occasionally in
September. To feed then is to
take a chance.
Summer pruning that stimu-
lateS new growth late in the sea-
son has much the same effect as
feeding on roses. and other tender
plants. These cultural practices
should be started early enough
in the season so that new growth
will have ample time to mature
before sharp freezing weather is
to be expected.
Too Much Protection.
Too much protection is another
factor that encourages winter in
jury. An abelia planted on the
southeast corner of a house in
Takoma Park suffered freeze in
jury each winter. In an exposed
situation in Silver Spring. similar
bushes seldom lost a twig. The
same applies to plants common to
the South. such as the crepe
myrtle, cahellia and Nandina.
Coddling is to be avoided because
it keeps the plants from maturing.
The common fig tree will suffer
injury and probably die if kept in
a protected situation. but where
exposed to wind and GOODNESS. it
will thrive and reach good size.
The most devastating winter in
jury, however. is one that we can
do very little about. Last fall a
sharp freeze passed through the
South, as far down as Mobile.
Ala, at a time when all plants
were in tender growth. The re-
sultant loss to almost every kind
of plant was depressing. Magno-
las and azaleas were killed to the
ground. Winter wheat. clover,
grasses and many other crops suf-
fered severe injury. Here in Wash
ington. the plants had reached
maturity (dormancy) and were
uninjured. We can do very little
beyond withholding moisture and
plant food to force a plant into
dormancy. The addition Of pot
ash has been reported helpful to
roses, although that plant food
might increase the plants resist
ance to disease which would have
the same end effect.
Acclimated Plants Best.
No doubt acclimated plants are
better able to Withstand unfavor'
able areas. Several years ago
local gardener, wishing to grow
the Yaupon Qlex vomitoria), a ma
tive of the deep South. bought
plants from several nurseries
Those obtained from nursery II
Oklahoma withstood local condi.
tions satisfactorily and the plant:
are still living, while plants OBJ
tanned from a Norfolk nursery
failed to thrive. The Norfolk ares
has climate tempered by the near
ness of the ocean and is les
rigorous than that of Oklahoma
Gardeners Of yesteryear. recog
nizing the value of acclimatet
plants, recommended the purchas'
of plant material from a mor'
northerly point. Today. we appl.
that rule to the more tender plan
material-plants that tend to grow
late into the fall and whose wooC
does not mature early.
For hardy plants from the north
the area of production makes littl'
difference. Canadian hemlock
grown in the south. where a lonl
growing season produces addet
size per year Of growth. still hav'
their inherent genetic hardness
This factor is widely recognized b.
the nursery trade and there ar
many large wholesale nurseries il
the South that supply Northern
retailers. The growing of varietie
adapted to this area in the Soutl
does not make them any less de
sirable-but, some gardeners suf
fer disappointment when they bu
Southern adapted varieties tina
are not acclimated and try then
here. Sooner or later they suffe
winter injury and are lost.