part 2 - The Maple Society

Record low: -38,5°C
Ume
Cold
This is the northernmost
location known to me where
Japanese maples are growing
More than peak cold, late frosts
and the short growing season
are the big limitations
The last spring frost is around
June 4th and the first frost in
autumn comes in mid September
Early March
Early April
September 3rd
Japanese maples
can indeed be
grown successfully
in Umeå, zone 4
Average snow
coverage seem to
give adequate
protection against
extreme cold
Late frosts, cold
winds and late
winter sunscald
are the main
threats for
Japanese maple
welfare in Umeå
The short (in days)
growing season is
partially
compensated by
the long (in hours)
duration of the
daylight
•
•
•
•
•
•
•
•
•
Acer japonicum
Acer japonicum ‘Aconitifolium’
Acer amoenum ‘Osakazuki’
Acer shirasawanum
Acer shirasawanum ‘Aureum’
Acer shirasawanum ‘Yasemin’
No palmatums
No matsumuraes
Most snakebarks perish
Maples successfully grown in
the ground for about 5 years
with winter temperatures
down to -30°C (-22°F)
•
•
•
•
•
•
•
•
•
•
Acer platanoides and its cultivars
Acer pseudoplatanus + cultivars
Acer triflorum
Acer tegmentosum
Acer sieboldianum
Acer pseudo-sieboldianum
Acer rufinerve
Acer tataricum
Acer carpinifolium
Acer campestre
The Umeå maples belong to a private
collector
200 km north, in Piteå, there is a public research center
where they study plant hardiness and have started planting
some Japanese maple species
It would be interesting for the Maple Society to establish a
link with them.
?
Acer shirasawanum
Acer palmatum
Acer japonicum
Acer amoenum
?
• It would seem puzzling, from the
distribution map, that A. shirasawanum
could grow in zone 4 in Sweden
• However a careful reading of Ogata’s
work shows that:
• In Shikoku it grows in the highlands of Mt.
Akaishi, Mt. Tsutsujo and Mt. Tebako
• In the Kanto district from 1200 to 1500m
• In the Hira mountains (Shiga Pref.) from 700
to 1100m
• In Omine mountains (Nara Pref.) from
1500m.
Acer shirasawanum
• Therefore this is a tree of colder
locations even though its range does not
extend northwards for reasons not well
understood.
Toulouåe
Summer drought, Low
rainfall and hot sun
Rainfall
Year
(mm)
Rainfall
June
(mm)
Rainy
days
June
Rainfall
July
(mm)
Rainy
days
July
Rainfall
August
(mm)
Rainy
days
August
Rainfall
Sept.
(mm)
Rainy
days
Sept.
Tokyo
1466
165
20
161
20
155
17
208
20
Toulouse
668
64
7
45
5
50
6
52
7
Sunshine
Year
(hrs)
Average
High
June
Sunshine
hours
June
Average
High
July
Sunshine
hours
July
Average
High
August
Sunshine
hours
August
Average
High
Sept.
Sunshine
hours
Sept.
Tokyo
1847
25
120
29
147
30,8
177
26,8
113
Toulouse
2009
24,2
207
27,6
245
27,5
238
24,2
195
Heat is not a
problem
Sunshine is a
problem
Low Summer rainfall
is a big problem
• Too much
sun
• Lack of
rainfall
• Too much sun
• Lack of
rainfall
More ‘beautieå
It is simpler to cope with the handicap of too much sun and
inadequate rainfall than with inadequate temperatures
To grow Japanese maples in Mediterranean conditions it is thus
necessary:
To provide protection from
afternoon sun
To provide protection from
afternoon sun
To cope with
low summer
rainfall you
have to water
Watering should
mimic conditions in
Japan which include
frequent rain and
good drainage
Keep soil moist
by watering
little but often
To avoid water
logging you must
improve drainage
Generous
yearly
mulching with
organic matter
Improves soil
structure,
drainage,
moisture retention
and acidifies soil
Maples could be successfully grown in Toulouse
50% wetter than Toulouse, albeit with some summer drought
which should require watering,