Abstract: The paper presents the results of a study conducted during the years 2000 – 2002 at the Production and Experimental Station in Bałcyny (53^o35’ N; 19^o51’ E). The objective of this study was to determine the suitability of two maize hybrids, Wilga (FAO 190) and Bzura (FAO 239), for the production of silage as dependent on sowing time (the last ten days of April – early sowing, the first ten days of May – sowing delayed by two weeks) and density of sowing (8, 12 or 16 plants per m²). It was demonstrated that the yield of silage raw material was determined by weather conditions in particular years of the study. The mid-early hybrid Bzura was found to be more suitable for silage production under climate conditions of the Province of Warmia and Mazury, due to a higher yield of both green matter and dry matter, and a higher quality of raw material. Sowing in the first ten days of May, as compared with sowing in the last ten days of April, provided more favorable conditions for plant growth and development, which resulted in a significant increase in the yield of green matter, dry matter and total protein, and in gross energy value. The density of sowing of 16 plants per m² ensured attaining the highest yield of green matter, while the highest yield of dry matter and total protein as well as the highest gross energy value were reported for the density of sowing of 12 plants per m².

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