hawkeyewx:
What have your temps. been like?
What I have seen here in Bolder Colo. has been S.nemerosa is breaking ground
We had snow the other night. So Yes wait for warmer weather.
The lupins are just breaking ground here in Colorado(Zone 4b-5b)no sign
of the verbascums yet but they too will be showing later as well.
My guarantica Black & Blue is up and growing in my Austin Garden but no bloom yet. Some
of my heat loving plants have just started coming back from our 17 degree
winter temps(in Austin) so patience is important.
Art

I uncovered my non-hardy salvias around April 1st. During the first two weeks of the month we had nice weather, some 50s, some 60s, a couple low 70s, and a couple low 80s. We then experienced the coldest stretch of mid to late April weather in many years... 30s and 40s for nine straight days, including an inch of snow early in that period. Our normal high is now in the mid 60s. The last two days we finally managed to get into the 50s, although we still can't get any sunshine. The next two days will be cooler again before we finally get back to the 60s at the end of the week.

The salvias I had covered with leaf bags and tarps are greggii pink preference, greggii x cherry chief, guaranitica black & blue, and guaranitica blue ensign. One of the pink preference is putting out new growth from the old wood and the other one has a couple tiny green leaves on one node so I know it is alive, too. The other salvias haven't shown any growth, although I know the blue ensign and cherry chief are green and juicy inside the lower part of the stem and the black & blues have juicy green tubers. I didn't expect it would take so long for new growth to appear.

My Scarlet Spires haven't returned since the bags were removed so I can relate to your uncertainty. They all returned last year so there still might be some hope. Other salvia more tender ones such as Mulberry Jam and involucrata are sprouting at the base and a Silke's Dream sent up one shoot which was frosted. Another thing to keep in kind is not all plants even when they are the same cultivar sprout at the same time. A row of unprotected greggii Wild Thing has been returning one at at time for about a month now with the last of them only in the past few days. The only rule that seems to apply is the older and woodier the clump the more iffy and slower the return. This might also be true for plants protected by bags. It is only my second year employing this kind of protection and presumably there is more to learn.

Don't give up until late May. Every microclimate, soil, is different. Here, in England, many species have sprouted early, but same species in other parts of the garden, have not. OK, some may have died, but after a very warm spring, am very optimistic. For example. I always winter outside plants of Indigo Spires here with no problems, all are now re-sprouting well.......but a friend just a few miles away, always loses his plants. (JUST as well I checked this before I sent the message.........as I had written "pants" instead of "plants"!!!