Our beautiful huge rosemary bush suffered severe die-off this year, no doubt because of that wicked cold spell. How much can I cut it back without killing it?
If it's anything like my Rosemary bush, it's probably already dead. No green leaves survived on it, but I had tip-layered it last year. That layer rooted and seems to have survived the cold, because its leaves are green. If your Rosemary has any green leaves, I would cut it back to those areas. Or else, you can just wait to see if any new growth sprouts; that will show what's still alive.
Yes, there are some green branches - I will try cutting it back to those. It's going to make it a very lop-sided plant! Thanks for your response.
I had the same concerns about my Rosemary bush, and the Lavender. Both appear to be dead. But I am sure we've had worse Winters than the one just past. A few years ago, I think temperatures dipped down to -15 degrees C to -20 degrees C, for a couple weeks straight, and the plants got through it fine. This past Winter didn't seem particularly harsh. So why die now?
Not particularly harsh, David? The temperature at YVR dipped to a low of -15.3 this winter; the last time there was anything comparable was in winter 2008/2009, when the lowest temperature was -15.2. Before that winter, you have to go back to 1968/1969, when the low was -17.8, the coldest it's been at YVR since records began in 1937 (tied in winter 1949/1950).
How about the duration of the cold, @vitog ? Was it longer than normal? It may have been coincidence, but my citrus trees produced heavy blooms this spring, perhaps due to a longer period of cold.
I didn't look up numbers to confirm, but the winter of 2017 stands out in my mind as miserable. We went to Mexico in January. It had snowed, partially thawed, re-froze, and temperatures went way down. We came back and Vancouver was still in a big freeze. Temperatures hadn't warmed up enough to thaw the snow; it was all still frozen hard like when we left. Our car, which we had parked at airport parking (Park 'N' Fly, I think) had a dead battery because of the cold. They had to recharge it to get the car started. That was the winter that I will remember as being hardest. Yet all our plants made it through. In terms of numbers, perhaps this past winter was colder. (I am surprised what a difference a couple degrees can make.)
Don't forget that we had a VERY wet November and Rosemary does not like wet feet..We keep our Rosemary bushes in a raised planter... Where'd that darned dog go....
The cold spell last December/January had 8 consecutive days with temperatures below -5 degrees C, including the -15.3 minimum. In January, 2017, there were two separate periods of 4 consecutive days below -5; but the minimum was only -8.4. That was pretty normal for YVR; I don't remember any problems with tender plants in that winter. By January, plants have had plenty of time to harden off. I've noticed the most problems with winter damage when we have cold arctic air in November.
My Rosemary - labelled as “Arp” - planted in container against the house (so a bit sheltered) … expired dead brown — I chose Arp because it is supposed to be cold temp tolerant then again - the sudden drop on temp — or a certain wind exposure etc makes a difference too (micro-climates at their micro-est) Back to Arp - it looked great last autumn 2021. we used to get a routine cold around USA thanksgiving it seems This yr winter 2021/22 it was cold and snow and ice that would not go away looking at the Britannia Range right now, low snow today - again Well we can all check back here in a few weeks about smoke and drought and heat perhaps :)
We get 100km+ winds in the winter (Howe Sound outflows), so -10 is much colder with wind chill. Lost 5 lavenders and two rosemary bushes and maybe a new Desert King fig that I started from a cutting a few years back. Was at GardenWorks, and a small rosemary was $25! Bought two base-ball sized ones, put them in terracotta, and will bring them into the greenhouse in the winter from now on.
I am thinking ahead to this winter and wondering what I can do to provide my plants some extra protection. (Hopefully, we don't experience a winter as cold as last winter for many years.) I've put a bag each of bark mulch around each plant. That should give the roots a little insulation for the coldest periods. Is there anything to do for the parts of the plants above ground? I've seen some YouTube videos where people wrap their plants in burlap, which acts a little like insulation. But isn't that blocking the light too? I suppose the burlap can be taken off in early Spring. Any other suggestions?
I would temporarily wrap plants with something like burlap only when arctic air is about to arrive. It can be removed after the arctic air is gone, although the plants don't need light when they are dormant. Most cloth-like materials will absorb moisture and become less insulating. I plan to use several layers of old, damaged floating row cover material over some of my Feijoa plants if I see forecast lows below -8 C this winter.
I try the same winter protection measures for my in-ground rosemary as I'm using for my figs: plastic tubes+snow. Last year my rosemary plants over wintered indoors. This year I brought two of 4 plants inside, but first of them died a few weeks after moving, and now the other is also deteriorating fast. Two in ground plants look good so far (this is my first ever experiment of growing rosemary in ground). My skipper grows rosemary in ground on Vormsi island for many years already, there winter is so much milder, that rosemary needs no protection.
I am circling back to this topic because I bought three more Rosemary plants this summer. Two Arp and one Blue Spires. Looking forward, assuming this winter gets a real cold spell, two of the plants are in pots and can be brought into the garage. This would mean they get no light. So the question comes up, how long can they be left in the garage? Are they dormant right now? Can they be left in the garage full-time until Spring? (If so, when to take them out?) Or should they be put inside only for the very coldest days, say, temperatures below -10 degrees Celsius? i.e., this would be a day-to-day decision. Or out during the day, in at night?
Best to do it on a day-to-day basis. Younger, more vigorous Rosemary plants take cold better than older ones (the reverse of many plants!), so keeping a succession of new plants over the years from cuttings is a good idea too.
Both you and the plants would be best off if they were heeled into some bark or sand outside and left there until spring.
