One more pic that really doesn’t do it any favors:

Depends on how cold it was. Annual vinca is a subtropical plant and will not tolerate very cold temps. Anything below about 40F will not be to their liking and much below that could kill 'em. Or at the very least, seriously set them back.

Coverings like bed sheets will only provide a few degrees of cold protection, so if it dropped below freezing on any of those nights, you are lucky the plants are still alive.

Not to mention vinca HATE cold/cool soil -- they tend to rot out. I would recommend pulling back the mulch temporarily to allow the soil to warm faster, that might help some.

not surprising you lost actual flowers ... they hate cold even more than the rest of the plant ...

all you can do now.. is give them a couple weeks.. and see what happens ...

its hard as the pix are pretty far away .. but it looks like there is significant unaffected leaves ... and if so... in those few weeks.. you ought to see new unaffected growth ...

i have seen much worse damage.. and had success ... but i also had patience to wait for them to take care of it themselves ...

they are injured.. not hungry.. fert is not a response at this time ...

im trying to be optimistic for you .. lol.. keep us posted ...

ken

I’m not familiar with all varieties of vinca, but we had perennial vinca ground cover in our yard in central NH and it is fine with very cold temps, snow cover, etc. if that is what you planted and you covered it, I think there is a good chance it will bounce back.

The plant in question is not the groundcover, Vinca minor, but annual vinca, Catharanthus roseus. Very different plant, very different growing requirements.