No response from anyone in your area so I'll give it a go, although in my climate rosemary is totally hardy. Firstly I would not prune it, either now or in the spring. Using it for cooking will prune it until it is a large bush and needs some renovation. I would not mulch over it but mulching around it won't hurt. I would not cover it with anything unless a deep freeze threatens. If the site is windy a screen a little way from the plant might help. No idea about anti desiccant but I don't like the sound of it.

I've never successfully overwintered rosemary though some in the area that have just the right microclimate are able to. I'm in the crossover area between zones 6a and 5b. I am sure I would have been able to overwinter it last year as our winter was the most mild in years - with the exception of April when all the fruit trees were blooming. Some tree fruit crops here, like cherries, were a total loss. Others like plums and apples were severely damaged as well.

I agree with flora. Don't prune. Mulch generally only fosters mold and rot damage and attracts small rodents in my opinion. If it survived last year in that location, see how it fairs this winter with the same care you gave it last year. You could, however, take some heel cuttings and bring them inside to see if you can propagate some new plants this winter.

FataMorgana

From the linked in article below:
Heel cuttings are made from side shoots produced on stems two or more years old. To make the cuttings, pull the side shoots from the main stem. Pull directly away from the tip end of the main stem. This usually leaves a heel of older, main-stem tissue attached to the basal end of the side shoot. The heel cutting also can be cut from the main stem with a knife.

FataMorgana

Here is a link that might be useful: propagating trees and shrubs

Thank you all for the suggestions. It is now a very bushy, healthy looking plant about three feet high. Actually there are two of them planted side by side. A few nights ago, we had eight (8) degree f temperatures with no discernible damage noted. We are in for a week of 40 degree plus weather and so I think I will jut leave them alone in their cozy little corner and hope that the added size and strength will bring them througf another winter. I do have a great supply of grilling skewer! Perhaps the Dept of Ag. knew what they were doing when they recently changed our zone designation from 6B to 7A!
Victor

I've come across some very hardy rosemary. Took some cuttings from a rosemary plant that has survived 3 winters here in zone 5. While it hasn't got extremely cold here yet this winter, we've been down to about -5F a few times, this rosemary is looking good so far.

The local nursery was selling arp rosemary with tags claiming hardy to -18F. Maybe rosemary is getting hardier.

Just a theory. Might be the variety. For years, I could not keep one alive. Came to find that the 'experts' steered me too far in 'no wet feet'... they DO like moisture, just not too much. I keep one on my sunporch winter and summer... move to shady part of the porch in summer. Spritz it, water it when the soil feels a little dry, and ignore it. Doing great. I think what they're most vunerable to is SHOCK... just my two cents' worth. They also might be like bay laurel, cold is okay, but windy spot is the kiss of death... I'm zone 6b.

"Arp" is the most hardy variety I know of if you are looking to try one in the northern reaches of its hardiness.

FataMorgana

I have 10+ plants of "arp" around my zone 7 climate (was 6b until recent update.) Since wind was mentioned above, I will add that I am in an extremely windy climate and the plants have no protection from the wind. I don't water them after they are established, although we get only 5-7 inches of rain a year. I don't do anything... and the plants all are thriving.

Honestly, I love my rosemary plants since they are evergreen, edible and don't need extra water... so easy!

Since the OP is in a similar zone, I would suggest checking your variety. Instead of babying whatever you have, plant an "arp" and leave it be. :)

Hi, everyone. Was over here on the Herb Forum looking for some more ideas. I grow a few herbs, Rosemary among them. 'Arp' is now listed as being hardy to Zone 6. So is 'Hill Hardy' also known as 'Madeline Hill', named after the famed Texas herb grower by that name. There is a white flowering variety that is also hardy to zone 6, but I don't recall the name. I'm growing 'Barbeque', hardy to zone 7.

I concur with Lolauren. Successful Rosemary plantings are all about the culture. Sharp drainage, some sand in the soil, sweet or alkaline soil (I add a little dolomitic lime to mine), and water sparingly (after it has been established; first year requires a bit more watering until the roots find their way). I don't fertilize mine at all, but just had fairly decent soil to start with.

Good luck!

Susan

I’m checking in on this thread seven years later (!) hoping someone has had some zone 6 success with Arp! I just got one from a highly reputable nursery here in southern New England (Logee’s in CT) and have it in a slightly raised bed with two boxwood flanking it for some protection. The garden is fenced on all sides and southern facing. We have such damp winters here, I’m worried—my experience with a plant labeled “arp” from Bonnie Plants via Home Depot (ya, i know) was a failure. That plant did not look at all like the tall, silvery Arp rosemary I got from Logee’s, so I’m hoping it was Mis-labeled. I’m curious about soil amendments—sand and gravel—and possibly a stretch Of exposed stone to the south that could collect & reflect heat in those deep winter days? My neighbor’s rosemary survives this past winter—it’s more and more like DC here in Rhode Island every year 😳 I’m taking cuttings indoors anyway ...