An experiment was carried out at Dubreuil, commune of Ducis, to assess the response of onion (Allium cepa L.) growth and production parameters to the use of organic mulch and planting density. The study was conducted using a complete randomized block design, with the six treatments repeated three times. The mulch factor included three modalities (control without mulch, vetiver root, wood chips) and the planting density factor included two modalities (4-row beds i.e. 285714 plants/ha, 6-row beds i.e. 428571 plants/ha). The data collected were subjected to analysis of variance and Tukey's 5% error test. The results showed that yield increased with the mulch of wood shavings and vetiver root compared with the non-mulch control and then with the six-row planting density. These results confirmed the effectiveness of mulch in suppressing weeds, increasing leaf length and also in retaining water in the soil.