Melon is a little popular vegetable to grow in Poland, due to high climatic requirements. Ensuring appropriate thermal conditions for plants growth is possible with relatively late planting seedlings. However, late planting does not guarantee high yield of good quality fruit. The factor enabling the earlier planting seedlings and improving the conditions of growth is the use of flat covers. The field experiment was conducted in 2008–2010 in central-eastern Poland. The effect of planting seedlings of melon ‘Malaga F₁’ (15 May, 25 May and 4 June) and the length of polypropylene fibre 17 g·m^-2 covering (by 4 and 8 weeks from planting, until harvest, control without covering) on the yield and economic efficiency of melon cultivation in the field was investigated. Most preferably the yield level and profitability of melon cultivation were influenced by planting seedlings on the 15 May and covering by 4 weeks. However, earlier planting decreased the share of marketable fruits in the total number of fruits. The highest share in the costs structure of melon cultivation had the costs of human labour.