Southern Hemisphere Plants
Many plants from Australia, New Zealand and the Southern part of South America are hardly known here. (South Africa is somewhat better represented) Only a few years ago many people didn't know that some Eucalypts are much hardier than the well known E. gunnii.
And also little known was the fact that the hardiness of these splendid trees largely depends on the provenance of the seeds.
The form 'Divaricata' (shown on this picture), is a very hardy and extra blue form. There are however even hardier species, in Australia known as "snowgums". ("gum" is a common name for Eucalyptus). For example Eucalyptus debeuzevillei is hardier, as is E. niphophila.
But much more remains unexplored! A promising plant for coastal areas in Northwestern Europe is Cordyline australis "Zuidland", a more frost resistant selection than the plants we currently find in the trade. "Zuidland" has a provenance from an area about 1500 km further to the South, and that makes all the difference! This plant is already available as a seedling (which is still too young to plant in your garden).
Another interesting novelty is Blechnum magellanicum, which has already sustained 10 degrees of frost
without any damage and 20 degrees of frost covered by a big container for shelter. This is very promising! Of course, we need a few more years of observation before we can make a sound estimate about the real hardiness of this fern.
A weakness of all plants from the Southern Hemisphere is their sensitivity to very dry and cold air. Under the influence of increasing wind the effect of sub-zero temperatures increases rapidly. For example, wind force 6 at 0 degrees Celsius has the same effect as 9 degrees of frost without wind! This explains why so many plants died in the winter of 2002/2003; they might have survived the frost alone, but not in combination with the extremely high winds we had in february.
If you are anxious to explore the exciting possibilities that plants from "down under" offer you, then the first step is providing shelter for them.
windchill table
|
Windvelocity |
Airtemperature in °C |
| Bf |
kts
|
Km/u
|
M/s
|
+8
|
+6
|
+4
|
+2
|
0
|
-2
|
-4
|
-6
|
-8
|
-10
|
-12
|
| 2 |
4
|
7,2
|
2
|
+8
|
+6
|
+4
|
+2
|
0
|
-2
|
-4
|
-6
|
-8
|
-10
|
-12
|
| 3 |
8
|
14,4
|
4
|
+7
|
+5
|
+3
|
+1
|
-2
|
-4
|
-6
|
-8
|
-11
|
-12
|
-15
|
| 4 |
12
|
21,6
|
6
|
+6
|
+4
|
+2
|
-1
|
-4
|
-6
|
-9
|
-10
|
-13
|
-15
|
-18
|
| |
16
|
28,8
|
8
|
+5
|
+3
|
0
|
-3
|
-5
|
-8
|
-11
|
-12
|
-16
|
-18
|
-21
|
| 5 |
20
|
36,0
|
10
|
+4
|
+2
|
-1
|
-4
|
-7
|
-10
|
-13
|
-15
|
-18
|
-21
|
-23
|
| 6 |
24
|
43,2
|
12
|
+3
|
+1
|
-2
|
-6
|
-9
|
-12
|
-15
|
-17
|
-20
|
-23
|
-27
|
| |
28
|
50,4
|
14
|
+2
|
0
|
-3
|
-7
|
-10
|
-13
|
-16
|
-18
|
-22
|
-25
|
-29
|
| 7 |
32
|
57,6
|
16
|
+2
|
-1
|
-4
|
-8
|
-11
|
-14
|
-18
|
-19
|
-23
|
-27
|
-31
|
| |
36
|
64,8
|
18
|
+1
|
-2
|
-5
|
-9
|
-12
|
-16
|
-19
|
-21
|
-25
|
-29
|
-33
|
| 8 |
40
|
72
|
20
|
0
|
-3
|
-5
|
-9
|
-13
|
-16
|
-19
|
-22
|
-26
|
-30
|
-34
|
Stastically Once every 10 years ...
there is a serious risk of loosing some plants from the Southern Hemisphere because of prolonged freezing weather. For me this means replant and start again to have at least (statistically) another 10 years of joy again with an increasing chance for long term survival because our climate keeps getting warmer and warmer.