The aim of the paper was to determine quantitatively thermal requirements of winter triticale and to define probability of reaching wax maturity within assumed dates. The paper uses the 1982-1996 data on winter tritcale phenology and the 1972-2001 meteorological data from 57 stations of the Institute of Meteorology and Water Management (IMGW). The relation between the length of interphases and the average air temperature at the interphase and also the total hours of absolute sunshine was determined with the linear regression method. The thermal requirements of winter triticale at particular development stages were determined with the totals of effective temperatures. It was found that in Poland winter triticale reaches wax maturity when the totals of the temperatures counted above 3^oC from the moment of stable revival of vegetation amount to 1158^oC. The probability of reaching wax maturity by winter triticale before July 20 varies from below 10% in the north-eastern and north-western Poland to over 70% on the area of Silesian Lowlands. By July 31 triticale reaches wax maturity all across Poland at least every other year and as for the Lowland of Poland – in each 9 out of 10 years.

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