Whole and ground spices

[AmandaN]

I have a stupid question.....

I have some whole cumin and coriander.  I know when you use them for say, Indian dishes that you dry roast them prior to grinding.
But I have ground spice jars as well for other dishes. 

If I wish to grind my whole spices to replenish my ground spice jars, do I just grind them, or should I roast them as well?

I am thinking that the ground spices are just that......ground only.

[Katya]

The reason for grinding whole spices when cooking is that you get a much better flavour.   When ground spices are kept for a time, they tend to lose their flavour.    The smell you get from newly-ground spice is so much stronger.

Pre-ground spice is easier to use, but if you are going to grind some and store it, I would suggest you don't do a big quantity.