Two field experiments were carried out during two successive winter seasons (2016/17-2017/18) at Agricultural Research Station, Kafr El-Sheikh Governorate, Agricultural Research Center, to study the effect of twenty four treatments which were a combination of eight weed control treatments (i.e., Against, Against with hand hoeing once, Floro, Floro with hand hoeing once, Stomp extra, Stomp extra with hand hoeing once, hand hoeing twice and unweeded check) and three planting population including 120, 180 and 240 thousand plants/fad on weeds control, growth characters, onion production and its quality. All tested weed control treatments significantly increased onion growth characters and yield during the two seasons. Weed control treatment by Floro at rate of 750 cm³/fad+ hand hoeing once at 45 days after transplanting, reduced percentage of dry weight of broad-leaved, grassy and total weeds at 60 and 90 days after transplanting by (97.08 & 96.39 %), (90.50 & 90.50%) and (96.20 & 95.20 %) in the average survey in 2016/17 and 2017/18 seasons, respectively, compared to unweeded check. The same treatment  produced the highest average bulb weight, marketable and total bulbs yield per fad by about 45.67, 74.56 and 59.78 % when compared with unweeded check in the average of both seasons, respectively with best storability along with bulbs quality at low cost of onion production, demonstrate that weed control is very important in the onion fields. Also, onion plant grown at 180 thousand plants/fad revealed a very promising effect for marketable and total yield with the average of 17.89 and 20.24 % in conjunction with a great reduction in the total weed biomass/m² at 60 and 90 days after transplanting by about 25.51 and 25.77 % in the two seasons compared to 120 thousand plants/fad., respectively. The maximum values of total soluble solids, percentage of dry matter in bulbs, and remaining marketable bulbs after storage for six months were achieved under the density of 120 or 180 thousand plants/fad in both seasons. Total bulb yield/fad showed highly significant negative correlation with each of dry weight of broad-leaved, grassy and total weeds as well as culls yield/fad. Therefore, the use of integration between Floro EC 24% as post-emergence herbicide at rate of 750 cm³/fad (21 days after transplanting) followed by hand hoeing once at 45 days after transplanting plus plant density of 180 thousand plants/fad is the best choice for the onion farmers of this area to achieve maximum onion bulb yield/fad, storability and quality of onions with higher economic returns.