need lavender tips, thanks for your help!

hi there,
i have several outdoor lavender plants-a few in the ground, a few in pots, including a french lavender in a pot that i love.
how do i encourage new colorful blooms? it seems that once a bloom has died and turned brown, it stays there and at least with my in-ground plants, very few new purple blooms have come up. i have been thinking that nature must eventually take care of those and they drop off, but i am awaiting purple flowers and they are few and far between (except with the french lavender, it looks great). the others are Madrid and something that looks like spanish lavender-rounder than longer, (not english lavender).
do i prune the dead blooms off?
i know this is a very remedial question, but i appreciate your advice as to how to keep having flowering lavender for most of the year. i'm in northern california, where it seems possible, at least i see flowering lavender all year round. thanks!