Wait. Are they potted or in the ground? When did you plant them? I planted some of mine the first week of April and they are just now starting to bud out. If you were caught by the freeze at Easter that could have set them back a bit too. Also, how warm are your day/night temps now? If you're still getting into the 40s at night and not up into the 70s during the day they may just be waiting for warmer weather. I'd give them more time.

Most are slow to break dormancy because of this wierd weather pattern thing this year. Be patient and if necessary bag them to save their precious inner moisture.
John

Two are in pots. One is planted. Today one in the pots put out two tiny little stems! Cheers! So you guys are probably right. :D

I'm in a way warmer winter zone than you are and I have 3 roses that are only just now putting out growth. Patience! it's still early.

would a root stimulator help?