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and mobile plastic tunnels; and the mobile greenhouse technique 

 will not be discussed here. 



Plants scheduled to be covered by cold frames or plastic tun- 

 nels are planted in the field in late July or early August, These 

 are rooted runner plants from growers own propagation fields , 

 from a nurseryman, or from cold storage. Plants from cold storage 

 are planted a month earlier than fresh-dug plants. Cold storage 

 plants, which were dug and stored the previous winter, produce 

 flower buds which must be removed. Otherwise, the flowering would 

 restrict plant growth, and an extra month of growth would then be 

 needed to produce plants equal to those produced by rooted runners 

 freshly dug from propagation beds. Although the use of cold stor- 

 age plants is more expensive, they frequently produce bigger plants 

 and the fruit quality is better because they produce fewer (but 

 sufficient) flowers. 



In late December or early January (earlier when there is a 

 threat of frost) , the cold frames are placed over the strawberry 

 plants to protect them against frost, wind and other unfavorable 

 weather conditions. This procedure advances harvest about 3 Aveeks. 

 There is more danger from frosts under plastic tunnels than under 

 cold frames. Thus, the plastic tunnels are not placed over the 

 plants until late February or early March. They advance harvest 

 about 10 days. 



Harvest advancement under cold frames and plastic tunnels is 

 slight in comparison to heated greenhouses. Therefore, production 

 of plants with shortened flower and leaf stems because of insuffi- 

 cient day-length and low temperatures is of no concern. If plants 

 do develop with shortened flower and leaf stems, they are less pro- 

 ductive, and this is of concern where heated greenhouses are used. 



The fruit ripened in cold frames and under plastic tunnels 

 are lighter-colored and softer than fruit of the same varieties 

 ripened in the open field. 



Growing in Fixed-Greenhouses 



Prior to planting in the greenhouse, the soil is fumigated to 

 prevent the transfer of soil-borne diseases to strawberries from 



Virus-free plants are frequently multiplied in propagation fields 

 by the gro\>fers. The grower may have his own field or with other 

 growers maintain a "collective" propagation field. Propagation 

 fields also are used as a source of runner plants for production 

 fields and "waiting beds." "Waiting beds" are special plants 

 that receive the best possible care in order to grow large plants 

 with numerous roots. Plants from waiting beds are used in green- 

 houses. 



