If they are already outside they are perfectly safe to transplant whenever you want to do it. They'll get a better head start on the season the sooner you do, actually. You've already hardened them off (or never let them get tender if they spent all winter out). Being the ground is actually easier on them than in pots, because the ground insulates.

Most herbs like well drained soil, and like to be fairly high & dry so i wouldn't over mulch them. Also, note that fresh wood will likely leach nitrogen out of the soil the first few months (part of the decomposition process), so it might be beneficial to allow it to mellow first. I'm not positive how long that takes, but would leave it longer than 2 mos. Anyone?

I think I'll spread the mulch to keep the weeds from growing back in and let that sit for a while. I'll put the herbs in a different part of the garden and use a different covering. How would they fare with pine straw? Or should I just not mulch them at all? Thank you so much for your quick and informative reply.
Lastly, what about a hydrangea that is still dormant? Would you transplant that now, or wait until after the last frost? I bought and planted 10 of them two years ago and with the drought I only had about 6 survive. So I have one hydrangea that's all by it's lonesome in the corner, barely noticeable and I want to give a more prominent position.

Thank you!!

I'm not sure about the hydrangea- i'll pass to someone more knowledgeable.

As for the herbs, if i mulched, i'd do it with a thin- 1/4" layer of regular mulch or some people even use pebbles, voleblock/permatill or pea gravel. The extra warmth of stone helps the herbs and it gives good drainage. If you get some of that horse manure, don't give much to your herbs. they really prefer very lean soil- and you'll get too fast growth with little oil concentration if you feed too much. For leafy herbs like parsley it's fine, though, as is mulch. It's the mediterranean ones that like high & dry & lean.

Spreading the ground wood should work fine- when you start noticing weeds growing you know the nitrogen effect is gone! I think it will age faster spread out like that too. If left in a pile it'll tend to begin to compost in the center.

I live in Portland and want to know if it is possible to transplant a feverfew once it has started blooming

It should be, but you'll have to baby it a lot more.