I visited Iceland on a Geography expedition with my school in 2024. As part of the expedition we visited Fridheimar (Geothermal greenhouse), which I found very interesting and gained the inspiration to write this article.
Greenhouse Farming in Iceland
Iceland is known for its harsh climate and inhospitable landscape which is unfavourable for the growth of plants. However, Icelanders have found a way to grow their own food. In 1924 they started building greenhouses taking advantage of warm soil in geothermal areas.
Iceland has been harvesting renewable energy for more than a century and is aiming for carbon neutrality by 2040. It has an abundance of “Green” renewable electricity from hydro and geothermal power plants providing energy for the majority of the country.
Iceland grows 90% of all the tomatoes eaten in the country and only 10% are imported, predominantly from Spain.
Fridheimar
Friedheimer is a geothermally powered greenhouse located on Iceland’s golden circle. It has 9 greenhouses with 1000 square metres for cultivation. It is a completely organic farm harvesting 2 tons of tomatoes a day. The farm grows 4 varieties and provides 65% of all Iceland’s tomatoes.
Heating:
There is a borehole (hot spring) 200 metres from the greenhouses providing an ambient supply of geothermal water at 95 centigrade (200 Fahrenheit). 60-80 litres of water is collected per second. The hot water is run through pipes in the greenhouse which exert heat. There are 25 kilometres of heating pipes in Fridheimer keeping the greenhouse at an ambient temperature of 25-30 degrees centigrade.
Irrigation/water:
The cold water is irrigated into the greenhouse for the tomatoes coming from springs in Fljotsbotnar. Since tomatoes are 90%-95% water its quality is essential. The owner says “Good quality water good quality tomatoes”
Climate control system
Each greenhouse is equipped with a climate control system regulating temperature, humidity, co2 levels and lighting which are linked to sensors throughout the greenhouse ensuring the perfect environment for the tomatoes. Photosynthesis is further enhanced by the addition of co2 into the greenhouse from a natural geothermal steam, further aiding their growth.
Lighting:
In order to maximise sunlight, the greenhouse glass panels are only 4mm thick to allow light to enter easily. However, heat can therefore escape easily so a lot of heat is needed to counter this. High sodium lights are used when there is little natural light available. The energy for the lights is from renewable geothermal resources which is minimal in cost. The lights are typically on 14-17 hours a day depending on the season. Fans are used to distribute heat and to provide air flow in the greenhouse.
Fertilisation of plants and pest control:
Iceland’s cool climate means they have little pests. However, if there are any in the greenhouses, they are taken control of naturally by spiders and other insects which are introduced by the owners, meaning the farm is completely organic and no chemicals are used.
Each greenhouse has approximately 1200 bees imported from Belgium/Netherlands which fertilise flowers of the tomato plant so they can become tomatoes. Each bee pollinates approximately 2000 flowers a day.
How the tomatoes are grown:
Tomato plants are grown from seeds in a “baby house” (nursery) until the first flower appears to ensure they are strong enough to go in the greenhouse. Plants are in their bed for nine months and reach up to 9 metres long, growing 25cm-30cm a week. Tomatoes are grown in soil mixed with minerals to ensure the plants have enough nutrients and minerals to grow. Tomatoes are only harvested when ripe to ensure the best freshness.
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