I know for sure shasta daisies like to be divided in the spring. You can't do anything to hurt the BES, so divide or move away! I'll let others comment on the rest.

I would divide all of them except the Columbine. I've never had to divide those. They usually just come up from seed all over the place. In fact, you can remove the seeds and put them in the freezer in a zip lock bag until Fall. In the Fall take those seeds out and throw them in the flower bed where you want them. You'll be surprised how well that works.

You definitely should not divide (not even cut it back) Russian sage in the fall. Leave it standing all winter, and cut it back and/or divide in the spring after new growth emerges. You stand an excellent chance of losing it if you do this in the fall.

Shasta daisies can be divided almost anytime, but the BEST time is right after they bloom.

I make a habit of dividing coreopsis in the fall. It always seems to do much better if divided every year.

I don't recommend moving or dividing the lavender then, either, especially in your zone. In fact, since lavender is much more shrub-like than perennial and tends to emerge from a single woody trunk/stem, I don't recommend dividing it at all. It can be propagated from cuttings or layered stems.

Thanks to all of you for the help. I obviously don't know much about all this. I'll report back next summer on the results of my fall/spring dividing and sowing.

Much appreciated!

An easy way to make more Lavender plants from your existing one is to select a low growing branch with abundant growth on the end and bury the stem with soil where it is closest to the ground. Place a rock on top of the point where it's buried. Leave it that way till next Spring. At that point it should have developed roots where the stem is buried and the new plant can be severed from the Mother plant, and moved to it's new location. Kathy

Columbine and lavender cannot be divided. The rule of thumb for dividing perennials is fall for spring blooming ones, spring for fall and summer blooming ones. Russian Sage (Perovskia) definitely doesn't want fall dividing--in fact, it often doesn't make it through the winter if planted from a pot in fall.