A Greenhouse in Iceland has the Answer
By Wendy Diaz EMGV
We were surprised when our New Year’s Eve trip to Reykjavik wasn’t cancelled due to the surge of the Omicron variant in late December, 2021. So, after several Covid-19 tests and a detour through Toronto, Canada we ended up having an enjoyable and very interesting trip thanks to the high vaccination rate in the tiny island nation of Iceland.
Our tour included lunch in a tomato greenhouse at the Fridheimar Farm[1] in the village of Reykholt on New Year’s Eve. Immediately after walking into the greenhouse from the cold outdoors, and after my eye glasses defogged, I was excited to share my experience with my fellow tomato-loving gardeners with photographs of the rows of towering tomato vines. Powered by abundant geothermal energy, the greenhouses grow a variety of vegetables for Iceland residents year-round but specialize in tomatoes. The farm also depends on visitors, 180,000 in 2019 alone, to their Little Tomato Shop and a Greenhouse Restaurant with a tomato-themed menu. The story of this family-owned farm (they also breed and show Icelandic horses) and of how they adapted during the pandemic and retained their entire 48 person staff during the covid-caused tourism shutdown was told in a recent Icelandic Times magazine article[2]. Twenty-five years ago, when they purchased the original farm of two greenhouses and a house it had already been using natural hot water for horticulture since 1946. The farm is located about 100 km west of Reykjavik by road and takes one hour and 20 minutes to get there from the capital city, and is well worth the trip!
Greenhouse Operation
In Iceland, thirty public district heating systems supply heat from geothermal energy to 90% of homes, but the Fridheimar Farm produces its own heat from its own hot water production well located only 650 feet (200 metres) from the greenhouses (one of 200 individual production well systems on the island)[3]. Hot groundwater enters the greenhouse at 203oF/95oC. The relatively thin 4 mm greenhouse glass is used to maximize sunlight entering the greenhouses, so about 200,000 tons of hot water is needed to heat the greenhouses each year. The irrigation water is pure water from the family’s own water supply. About 2.5 megawatts of electrical power (equivalent to the needs of a town of 7,000 people) for artificial lighting is required to grow plants year-round and in the long dark winter months this close to the Arctic Circle. It is supplied by electricity generated from public hydro and geothermal power plants. The artificial lighting is automatically switched off by the climate-control computer system when natural sunlight levels are optimum. The system also monitors temperature, humidity and carbon dioxide and with the latest technology is linked to a mainframe computer connected to the internet which can be adjusted remotely.
Plant photosynthesis is promoted by adding carbon dioxide (400 tons annually) which is transported by a tanker truck to the greenhouse storage facility and derived from nearby natural geothermal steam source. They use locally derived pumice (from the Mount Hekla volcano) as a growing medium, which is used for several years, and allows for simpler control of moisture and fertilization than traditional soil mixtures. Their production is pesticide free but they use biological control such as the predatory mirid bug Macrolophus pygmaeus. It consumes all the main tomato plants pests.
They grow a variety of tomato cultivars such as Flavorino cocktail, Piccolo, Sweetdor and plum tomatoes. The plants are started from seed in the nursery greenhouse and then transplanted into the harvest greenhouse after about six weeks when they start to flower, and in 7 to 8 weeks the first tomatoes start to ripen.
About 1,200 Bumble bees imported from Holland pollinate the tomato plants. Plants are planted twice per year using the method of interplanting where young plants are planted between the older tomato plants for continuous harvesting. At Fridheimar, two tons of tomatoes are produced every day in 11,000 m2 (118,000 ft2) of greenhouse space. They do not export their tomatoes for quality control reasons.
Rows of tomato vines of Piccolo (red) and Sweetdor (yellow) tomato cultivars in the Restaurant Greenhouse. Photos taken by Wendy Diaz
Unique Geology of Iceland
Iceland’s unique geology makes growing these amazing tomatoes possible, even in an environment that is cold and dark for much of the year. The Mid-Atlantic spreading ridge, where Iceland is situated, separates the North American and the Eurasian tectonic plates. Magma migrates upwards to the earth’s surface through 30 volcanic systems throughout the island. Water filtrates through fissures and faults in the bedrock until it comes near hot magma intrusions in the earth’s crust where it is heated up. The resultant hot groundwater is extracted through production wells and is used to produce electricity and hot water for domestic and commercial use. The deeper the production well the hotter the water. Pumice (growing medium) is volcanic rock that is highly porous and typically of a silicic composition. It is formed when molten magma has been frothed up when gases in it escape. It then cooled and solidified quickly during the volcanic eruption[4]leaving abundant vesicles within the harden rock.
Lunch
The large bowl of homemade tomato soup made from their freshly grown tomatoes was served buffet-style with sour cream, cucumber salsa, butter, fresh herbs and delicious home-baked bread along with a yellow cherry tomato and an Icelandic cheese kabob. The bread in Iceland is excellent by the way. They even have other dishes and beverages made from tomatoes such as tomato beer[1]. The Green-tomato and apple pie a la Fridheimar with whipped cream was delightful.
Lunch in the greenhouse restaurant included tomato soup and home made bread with Icelandic cheese and cherry tomato kabobs, cucumber salsa, butter and sour cream. Apple pie and whipped cream dessert. Photo by Wendy Diaz
We thoroughly enjoyed our lunch at Fridheimar Farm. We also appreciated learning about this very special farm that provides fresh produce to fellow Icelanders on this very unique Island. Iceland leads the world in sustainability by using wisely their geothermal energy resources and clean water. We left wanting to come back (in the summer) to the ‘Land of Ice and Fire’.
References:
[1] https://www.fridheimar.is/en
[2] https://icelandictimes.com/wp-content/uploads/2021/08/IT-English_45.pdf
[3] https://www.south.is/en/service/on-geothermal-exhibition-at-hellisheidarvirkjun
Extension Master Gardener Volunteers of Durham County 