Quinoa is gaining importance globally owing to its nutritional quality and its adaptability under variety of conditions. However, limited information is available on the impact of planting techniques on growth, morphology, and yield and biomass accumulation under irrigation conditions. To the date, no ideal planting technique (sowing method) has been reported for the flat irrigated land for better adjustment of quinoa in a crop rotation. To test the hypothesis, a two-year field study (2013–14 and 2014–15) was carried out at University of Agriculture, Faisalabad, Pakistan. The experiment comprised of four planting technique bed sowing (BS), ridge sowing (RS), flat line sowing (FLS), and sowing in standing water (SSW) in main plots, and two quinoa accession (A7 and A9) in subplots. The results showed that BS method improved the morphological attributes viz. stem thickness, main panicle, main panicle, thousand grain weight, grain yield, and harvest index as compared to SSW. Regarding the quinoa accessions, A9 performed better than A7 for morphology, biomass, and yield. Panicle number per plant was positively correlated with harvest index and main panicle weight in 2013–14, while 1000-grain weight and harvest index had a stronger correlation during 2014–15. The average and maximum biomass production rate of A7 in BS plants were relatively higher than other sowing techniques either for A9 or A7. Our data suggest that the BS method is a relatively better planting technique and A9 quinoa accession is a suitable genotype to obtain a high targeted grain yield under irrigated conditions.