The presented experiment was conducted at the horticulture nursery of college of agriculture, Gwalior, during the rabi seasons of 2019-20 and 2020-21 with same treatments and same site. The experiment was laid down in factorial randomized block design with two factors viz., Seedling age and bio fertilizers combinations along with 15 treatments combinations and three replications. The factor one have three levels viz., S-1 6 weeks, S2-7 weeks and S3-8 weeks whereas second factor BF1- un-inoculated (control), BF2- Azotobecter, BF3- Azotobecter+ PSB, BF4- Consortia (Azotobecter+ PSB + KMB) and BF5- Arka Microbial Consortium (Azotobecter+ PSB + ZSB). Based on pooled analysis maximum available zinc (0.55 mg kg-1) was recorded with 8 weeks old seedling and evaluation of different biofertilizers the maximum available of zinc (0.61 mg kg-1) was recorded with Arka Microbial Consortium (Azoto+ PSB + ZSB). Thus, the onion seedling of 8 weeks old transplanted with inoculation of Arka Microbial Consortium (S3 x BF5) recorded significantly higher available zinc (0.69 mg kg-1) than rest of treatment combinations.