Although we can't tell for certain from photos alone, the plant is probably dead or so weakened by the loss of most of its stems that any regrowth may be limited and not worth waiting for. (That is, replacement of the plant may be more practical instead of waiting all season to see how much recovery it's capable of.) Rosemary is at the edge of its cold tolerance in Maryland and DC, and while mild winter temperatures (both naturally and due to the warming effects of city pavement) can help it pull through, a cold snap after a mild spell can cause considerable damage. This year we have one or two of those episodes already (the first around late December) and we're already seeing lots of "winterburn" damage on other evergreen shrubs in MD and DC. Dry weather patterns can also worsen the risk of winterburn or branch dieback during such cold snaps, though rosemary is much more sensitive to good soil drainage than some shrubs and is equally at risk of dieback from soggy conditions.

If it is alive, pruning should take place once new growth has resumed so you can more easily tell how far any given stem has died back. This may be around April or so, depending on weather trends. You won't have to remove dead foliage, as they'll fall off on their own (if the stem itself is alive; they may cling on if the stem is dead). As for pruning method, you'd just be cutting off any growth which isn't producing green foliage above a certain point, even if that means trimming off most of the current branches pretty close to the ground and waiting for the plant to rejuvenate from new stems arising from the roots. How many roots survived the cold is hard to predict, though mulching in autumn with a layer about 2 to 3 inches deep can help insulate them to a certain extent.

It's a little early to trim roses yet, though if done now it's not likely to cause serious long-term problems for the plant. (When rose wholesale nursery growers ship plants to their nursery customers to pot-up for sale, they arrive already cut back, and those shipments occur in late winter.) Home rose growers usually trim around late February to early March in our region. Shrubby roses (as compared to climbing roses, which are maintained taller) tend to be trimmed down to around 18 inches off the ground, though this is not a hard-and-fast rule.

When pruning, remove spindly, weak canes (stems) and any that are crossing-over and rubbing up against each other as this risks creating wounds which can become infected. (Stems growing into the canopy instead of outwards away from it also just add to foliage crowding which also increases the risk of disease issues on the foliage during summer. Thus, they too are removed so the plant can focus on growth that will be more productive, which are canes growing outwards from the center of the plant.) Trim just above a bud (which should become more prominent on the stems the closer we get to the break of dormancy) and make sure pruners are sharp so the cuts are clean and don't result in a crushing of the end of the stem.

Miri

Thanks so much Miri! This is very helpful. I also have 2 vines (that I think are clematis, though not sure) that aren't looking too good. The first photo on the chain link fence in my front yard and the second is on the shed in myn back yard, both taken today 2/28. The third photo is when it was healthy in August. It produces small white flowers, i think in late spring. The shed vine seems to be doing better than the fence vine, but both don't look great. If you have any advice on whether i should prune back the dead folliage or leave it alone to see if it rebounds, that would be appreciated. Thank you!

You're welcome.

This looks like Clematis armandii, which is a species of Clematis that is barely winter-hardy in our area. (Due to the urban heat island in D.C., it would probably be more reliable most winters there.) It's also the only Clematis grown here that is evergreen, at least when not singed by winter weather. This damage looks like winterburn, which we're not surprised to see given the winter we've had thus far - while it's been mild overall, the two or more incidences of warm spells followed by a rapid drop to near-freezing caused damage on a range of evergreens, even if that damage took a while to manifest.

The plant will drop the damaged leaves, and if any stems themselves died back, that will become more evident as we get further into spring, when new growth appears. At that point you can trim off the dead tips so you can see how far down to cut. If the roots are otherwise healthy, rebound growth should be good and the plant will recover at least some of its former size over the course of this growing season. Since this Clematis flowers on "old wood" and would have small dormant flower buds present on the stems during winter, those might have been lost this year, so don't be surprised if it doesn't flower much (if at all) this year due to the winterburn.

Miri

Unfortunately the Clematis appears to be dead, though to be fair, it might have died earlier this season since evergreen plants can be notorious for not looking as damaged as they really are due to the slow-to-brown nature of the foliage. We've been so dry this growing season so far that, unless the vine was being checked for water, winter-weakened roots might have struggled to keep the top growth alive. If accidentally over-watered instead, since Clematis are not tolerant of saturated, compacted, or poorly-drained soils, that might have lead to stem dieback in addition to the leaf loss, since the splitting stems definitely indicate they are now dead. Clematis Wilt can kill above-ground growth but we don't know how prevalent that fungal disease is for Clematis armandii in particular since it's so infrequently grown.

It's hard to determine what killed a plant after the fact, so you can either trim back all above-ground growth and see if new sprouts appear from the roots (which would suggest enough root vigor remains for the plant to possibly rebound) or remove it and replace it. If you do dig it up, see if any roots look mushy and pull apart easily, though sometimes root decay is a secondary issue and root mushiness developed after they died instead of being the primary reason they died back.

Miri

Thanks for letting me know! It was a great plant until its demise :(

You're welcome.