The objective of the research is to justify the geometric parameters of tunnel type temporary coverings for growing early seedlings of cucumber using drip irrigation in the Lower Volga Region. As a working hypothesis of the study was accepted a proposition about the ability of using the advantages of drip irrigation for effective cucumber growing from seedlings in plastic tunnels providing to obtain the planned yield of 50-90 t/ha while optimizing water and nutrition soil regimes and the geometric parameters of plastic tunnels. The experiment results showed that the use of 1-meter wide tunnel coverings allowed optimizing the thermal conditions of air and soil, which provided a good survival of cucumber seedlings, strong growth, and early coming of fruiting phase. In 1-meter wide tunnel coverings the transition to fruiting phase has occurred by 4-5 days earlier. The earliest coming of fruiting phase was observed at the fertilizing dose of N100P60K0 and the pre-irrigation soil moisture of 70 % of field capacity (FC), which allowed beginning the first harvest at the third decade of May and the bulk deliveries of production at the first decade of June. At the fertilizing dose of N240P140K200 and the pre-irrigation soil moisture of 90 % FC, photosynthetic productivity has increased up to 3.67 g/m² per day at the crop yield of 81.8 t/ha in 1-meter wide tunnel coverings, against 3.16 g/m² per day and 43.3 t/ha in 0.5-meter wide tunnel coverings respectively. Using of plastic tunnel coverings by the width of 1.0 m provides an opportunity to get planned yield of seedling cucumber at the level of 70 t/ha. This requires applying mineral fertilizers at the dose of N170P100K100 and maintaining the pre-irrigation soil moisture at the level of 90 % FC by conducting 24-32 irrigations of 90 m³/ha.
