Dear Ejaz!

Please You see in this guidlince (p19,

http://tools.thermofisher.com/content/sfs/manuals/Insect_Cell_Lines_UG.pdf

Maintain mid-log phase cell density. When Sf9, Sf21, and High Five™ cells reach a density of 2 × 106 to 4 × 106 cells/mL, they should be passaged at 3 × 105 to 5 × 105 cells/mL. (page19)

Page 23-26

Sf9 80% Grace's Insect Medium, Supplemented 10% FBS, heat-inactivated

Thank you Debasish Kumar Dey

Yes, The initial cell density was low.

The cell is growing very slowly.

I am changing the media after 3 to 4 days and checking the cells under the microscope.

This article can be helping you

Thank you Rawaa Aswad

I am already following the same guideline/protocol.