microbiology
posted by micro .
How do i plot a semi log graph for OD vs. time? The values for OD are under 1

adjust ur scale and use Eve
numbers
try using ln instead of logs
dont be afriad to start ur graph later...instead of at 0 or 1 
There are semilog graph papers that you can use.
The time scale is probably linear, and the diameter is in log scale (or the other way round).
The log scales are in cycles of 10, in your case, would be 0.001 to 0.01, 0.01 to 0.1, 0.1 to 1, etc.
If you don't have semilog graph paper, then you can take log and plot the value of log. The cycles can be adjusted accordingly.
See, for example:
http://course1.winona.edu/sberg/307s09/Labs/documents/SemiLog_files/SemiLog_22632_image001.gif