Oat (Avena sativa L.) is an important self-pollinated fodder crop of family Poaceae. A field experiment was conducted at CCS Haryana Agricultural University, Hisar to study the effect of date of sowing and days to cut foliage on seed yield and quality of oat. The oat (variety : HJ8) was sown with three different sowing viz., (Normal: 6 Nov. 2016 (D1) ; Late : 2 Dec. 2016 (D2) ; Very late: 2 Jan. 2017 (D3) under recommended package and practices in a plot size of 5 m2 (4.0 m x 1.25 m) with row to row spacing of 25 cm for each treatment in three replications by using factorial RBD. The treatments also consisted of three days to foliage cut after sowing The foliage cutting was taken to make different treatments i.e. C0 (no cutting), C1 (one cutting at 50 days after sowing) and C2 (65 days after sowing) C3 (80days after sowing). The investigation resulted that delay in sowing time and days to foliage cuttings reduced the plant growth, seed yield and quality of oat. The crop without cutting of foliage gave the maximum plant growth along with highest seed yield which was followed by cutting at 50 days after sowing and lowest performance was observed in the last sowing in which cut was taken after 80 days. The delay in sowing and increase in number of days after cutting of oat significantly reduced the growth parameters of plant such as plant height, number of tillers per plant, number of seeds per inflorescence, number of seeds per inflorescence and seed yield. The best quality seed with highest value of seed quality parameters such as test weight, standard germination, seedling length, seedling dry weight, vigour index-I, vigour index-II, field emergence index and seedling establishment, was harvested without foliage cutting followed by one cutting at 50 days in normal sowing.