Our coordinates at Iso-orvokkiniitty in Karjalohja are lat 60° 13.985′  lon 23° 41.966’. So we are in South-West Finland 85 km west from Helsinki.

60° North is pretty north if you look at the world map. Apart from Helsinki and southern Finland, other places that are roughly at 60° North are Stockholm (59°), Oslo (59°), St Petersburg (60°) and Anchorage (61°). However if you would travel around the world on the 60° latitude circle, for the most part you wouldn’t encounter a lot of fellow people.

The thick circle on the map is the Polar Circle. 60° north is the circle that passes the south coast of Finland, south tip of Greenland and south coast of Alaska. 60° north is about 800 km south of the polar circle.

The reason why we can live and farm up here is the Gulf Stream which brings warm water from the Mexican Gulf over the Atlantic to North-West Europe increasing the temperatures in f.ex. Norway up to 10 degrees Celsius compared to other regions at the same latitude. While Norway has a very oceanic climate, Finland is a bit more continental and the more east you go on the same latitude the more continental it gets. If one is frustrated with the lousy winters we have nowadays in southern Finland – caused by climate change – one could obviously go 1000 km north to Lapland. However going 1000 km east would have pretty much the same effect. Only it’s more difficult to get there and there are no ski resorts…

The Gulf Stream by RedAndr – self-made, used map from http://www.ngdc.noaa.gov/mgg/image/2minrelief.html, GFDL, https://commons.wikimedia.org/w/index.php?curid=3492801

While we are pretty north in Finland the climate is better than you might expect. But we are definately north in terms of light. Due to the high latitude day lengths vary dramatically between summer and winter. Day-length at 60° at mid-summer is 19 hours but considering twilight it doesn’t become pitch-dark at all. In the winter it is of course the opposite situation. The annual amount of solar energy is roughly the same as in Central Europe or South England but the difference between summer and winter is bigger. Solar panels produce in December only 10% of what they produce in June.

According to Köppen’s climate classification, Finland belongs wholly to the temperate coniferous-mixed forest zone with cold, wet winters. The mean temperature of the warmest month is no lower than 10°C and that of the coldest month no higher than -3°C. Rainfall is moderate in all seasons. South-western parts of Finland including Karjalohja belong to hemiborealic mixed forest zone including hazelnuts and blue anemone.

Monthly average temperatures (green line) and rainfall (blue pillars) in Karjalohja.

For annual plants the main limiting factors in Finland are length of growth season (>+5C) and effective temperature sum (cumulative temperature sum over +5C also called GDD – Growing Degree Days above 5C). The thermal growth season in Karjalohja is over 185 days and the effective temperature sum is over 1400 degrees putting Karjalohja into the most favourable part of Finland in terms of climate.  The temperature is in average permanently over 5C by 22nd April and until 27th October. Rainfall per year is 700-750 mm and during growth season 380 mm.

Growing Degree Days above 5 C in Europe.

For perennial plants winter temperatures are critical as a single cold winter can kill perennials that are not adapted to cold. Looking at the two maps you can see that in terms of winter hardiness similar winter conditions to the south-west Finland can be found far more south in Balkans or north of the Black See. But in terms of temperature sums those regions are far warmer in the summer than Finland. Also in North America regions with similar winters to south Finland are far more south and far more continental, i.e. far warmer in the summer. It is difficult to find an other region with similar climatic conditions.

The map divides Europe into 11 hardiness zones. Karjalohja is just barely in zone 6 – the Hemiboreal zone which in Finland is often called the “Oak zone” –  together with a big chunk of Eastern Central Europe south from us. However the map does not factor in rainfall, summer highs or the temperature sum – it focuses on winter hardiness. The map is from https://www.gardenia.net/guide/european-hardiness-zones
Precipitation (left), evaporation (center) and surplus water (right) in Finland. While rainfall is low by European comparison, evaporation is even lower and therefore there is a lot of surplus water (300-400 mm/year in South Finland). That’s why large parts of Finland were naturally wetlands until drained by humans. Nevertheless spring and summer draughts are possible because most of the evaporation happens in the summer and the autumn is the more rainy season.
For the purpose of planting perennials, Finland is divided in 9 zones based on the length of the growing period, temperature sum and winter cold temperatures. Karjalohja is in the most favourable 1B zone.

The average wind speed (at 50 m height) is 5,5 m/s and the prevailing direction of winds is west /south-west.

Forest and trees

Even though South-West Finland, including Karjalohja, belongs to the hemiboreal “oak  – hazel nut zone”, forests are composed by far mostly by pine (Pinus sylvestris), spruce (Picea abies) and birch (Betula pendular – also B. pubescens). Actually 97% of timber in Finnish forests is pine, spruce or birch. Other tree species natural in Southern Finland include:

  • Populus tremula – Aspen
  • Alnus incana and A. glutinosa – Alder
  • Sorbus aucuparia – Rowan
  • Salix caprea – Goat willow (and other Salix sp.)
  • Prunus padus – Bird cherry
  • Corylus avellana – Hazel
  • Juniperus communis – Juniper
  • Querqus robur – Oak
  • Acer platanoides – Maple
  • Tilia cordata – Linden
  • Fraxinus excelsior – Ash
  • Ulmus glabra and U. laevis – Elm
  • Larix decidua – European larch

Oak, Maple, Linden, Ash, Elm and Hazel are in Finnish called “jalopuut” which literally means noble trees.

Most forests in Finland are managed in a rotational system of several decades ending in clear cutting and replanting. Only the new Forest Act, which came into force at the beginning of 2014, makes using continuous-cover silvilculture legal. (1)

Soils in Finland

Coarse mineral soils and organic soil types are common in Finland. Glacial till is the most widespread deposit in Finland and is primarily covered by forest vegetation and they are podzol soils. Almost all land, which can be cultivated, has been cleared for agriculture (8% of land area in Finland). Few clayey or silty soils exist under forest vegetation but are reclaimed for agriculture and have artificial drainage (2). One third of the fields contain clay soil types. The clay soils concentrate in Southwest Finland. The share of peatland in the arable land areas of Lapland, Northern Ostrobothnia and Kainuu is 20–40%. A quarter of arable land in Ostrobothnia and Southern Ostrobothnia consists of organic soil types. The pH levels of topsoil are naturally low everywhere in Finland, meaning that Finnish soil is acid. A low nutrient content is typical of Finnish arable land.

The main soil type in Finland and the Nordic countries is podzol soils (spodosols in “American”). http://culter.colorado.edu/~kittel/soilmap_eropsls_umn.jpg
Soil types in Finland: Yellow areas are glacial till ( unsorted glacial sediment).
Brown areas are eskers.
Red areas are sandy soils.
Most fields in South Finland are clay soils (grey areas).
Sorted soils consist of sand (hiedat + hiekat) (2 mm – 0,02 mm), silt (hiesu) (0,02 mm – 0,002 mm) and clay (saves) in different compositions.

(1) https://www.smy.fi/en/forest-fi/forest-facts/forestry/

(2) Problems encountered when classifying the soils of Finland.
YLI-HALLA, Markku and MOKMA, Delbert L.

This article is part of my Permaculture Diploma Portfolio.

[Erkki’s DPA main page][The Portfolio]


Created 24.1.2018