The purpose of this thesis is to describe and analyse the reception and development of the orangery in the county of Uppland, Sweden, during the 18th century. A main obstacle for the gardeners and their governors must have been the local climate in Uppland, a county at the south border of Norrland, the very north part of Sweden. The local climate during the 18th century in Uppland was rather cold with yearly temperature averages well under the “normal” during Baroque and Renaissance time. Two questions are discussed in the thesis. First question is: could the orangery buildings serve the purpose to protect fruit-trees from the harsh climate in Uppland i.e. had the orangeries built during the 18th century in Uppland at Walloon furnaces the expected capability to allow Asian fruit-trees like Citrus to pass the winter? The second question is: were the gardeners capable to force citrus blossoms to fruit? The study is based on sources of different kinds, such as gardening accounts from Walloon furnaces, contracts of service, inventories, wage bills, estate inventories, gardening manuals, horticultural handbooks and travelogues. To be able to go more closely into the matter I have done simulations of some orangery buildings thermal behaviour by using a building performance simulation software called IDA. The answer to the first question is that the orangeries served their purpose, at all events during normal winters. But during extreme winters the citrus trees must have been damaged. And the problems with importing rare Asian fruit-trees via the Netherlands, Portugal and Italy were overwhelming. The ambitions to acclimatize the trees to the harsh climate north of Stockholm, at the borderline to the north part of Sweden, were admirable. The whole idea of creating gardens of central European style and to build and maintain orangeries at high costs in the severe climate of county Uppland must have been a central European idea of lifestyle, or more likely the pleasure of the governers own satisfaction. The answer to the second question in the thesis is that I have not found any proof for production, even in a very small scale, of any citrus fruits in orangeries at Walloon furnaces in Uppland during the 18th century. / QC 20100714