(With apologies to Messrs. Cahn and Styne.)
On Christmas Eve, the daytime temperature here in Warsaw set a new record high of 61° F (16° C.) On Christmas Day, the temperature got up to 55° F. The normal high this time of year in this part of the USA is 33° F, just above freezing.
Temperatures have been above average all autumn. I couldn't find certain confirmation, but I think both October and November were the warmest on record here, and December may well turn out to set a record average, too. Our first frost didn't arrive until the first half of November, a month later than usual. So far we've had exactly one - count it, one - snowfall that required me to get out the snow shovel. (It did give me a chance for a nice picture.)
There is at least one obvious and major reason for the unusual weather. There is a well-established correlation between the presence of a strong El Niño phenomenon in the eastern Pacific and milder-than-average winters across much of the USA. The present El Niño is unusually strong in many regards, which goes a long way to explain why, in spite of the calendar, we've been running around in shirtsleeves more often than jackets!
(I consider the jury to still be out on the question of atypical global warming. I'm waiting for more conclusive evidence, one way or the other.)
The unusual warmth has of course affected my trees. Buds on several of my hardy trees started to swell in early December, as if spring had arrived, and swelled enough that I became concerned! The danger, for any who don't know, was that the trees would start to actually push new growth - and then the weather would return to normal and the tender new growth be killed by freezing temperatures. If that happens, a tree has expended some of its stored reserves for nothing.
I'm thankful that concern hasn't turned into reality. Most likely, I think, because of the shorter days as the winter solstice approached, the buds have stopped swelling and the trees appear to have gone into dormancy. I was glad to see the needles on my yamadori ponderosa turn to their normal winter shade.
Normally, my tropical trees are settled in the Crate by mid-to-late October. This year, I moved them into their winter quarters on November 28th. (With some incredulous shaking of my head at the late date.) I had been doing the "tropical two-step" with them for a couple of weeks by then, moving them indoors overnite when the lows fell into the upper 30's F, then back outside during the day. With daytime temperatures often in the 50's F, I wanted to give them the advantages of natural sunlight for as long as I could. But by the 28th, enough was enough.
And sometime in the next couple of weeks my half-hardy trees will be moved into the mudroom, and the hardy trees will go under their rack in the side yard.
The long-term forecasts call for above-average temperatures for the rest of the winter. In view of that, I've considered leaving my hardy trees out and just making sure they were protected from hungry and inquisitive critters. But a recent blog post by Michael Hagedorn on winter chilling requirements led me to change my mind.
The gist of what Hagedorn says is this (unless I missed something.)
Once my hardy trees are under the rack, they won't be as much affected by temporary temperature spikes that would interrupt their chilling requirements. So when spring does come, they'll be more likely to break dormancy on something approaching a normal schedule, and then grow well next season. The fabric that covers the rack will also serve to break the wind, and will hold in the fumes of the mothballs I use to discourage chipmunks, squirrels, and other cute-but-destructive little scoundrels.
To see Michael Hagedorn's post on hardiness and winter chilling for yourself, please click here. The post is thoughtful and well-written, and I recommend it.
On Christmas Eve, the daytime temperature here in Warsaw set a new record high of 61° F (16° C.) On Christmas Day, the temperature got up to 55° F. The normal high this time of year in this part of the USA is 33° F, just above freezing.
Temperatures have been above average all autumn. I couldn't find certain confirmation, but I think both October and November were the warmest on record here, and December may well turn out to set a record average, too. Our first frost didn't arrive until the first half of November, a month later than usual. So far we've had exactly one - count it, one - snowfall that required me to get out the snow shovel. (It did give me a chance for a nice picture.)
 |
| Japanese maples branches flocked with snow, beside the church we attend. |
There is at least one obvious and major reason for the unusual weather. There is a well-established correlation between the presence of a strong El Niño phenomenon in the eastern Pacific and milder-than-average winters across much of the USA. The present El Niño is unusually strong in many regards, which goes a long way to explain why, in spite of the calendar, we've been running around in shirtsleeves more often than jackets!
(I consider the jury to still be out on the question of atypical global warming. I'm waiting for more conclusive evidence, one way or the other.)
The unusual warmth has of course affected my trees. Buds on several of my hardy trees started to swell in early December, as if spring had arrived, and swelled enough that I became concerned! The danger, for any who don't know, was that the trees would start to actually push new growth - and then the weather would return to normal and the tender new growth be killed by freezing temperatures. If that happens, a tree has expended some of its stored reserves for nothing.
 |
| Buds swelling on a hybrid yew (Taxus x media 'Densiformis',) December 13, 2015. |
I'm thankful that concern hasn't turned into reality. Most likely, I think, because of the shorter days as the winter solstice approached, the buds have stopped swelling and the trees appear to have gone into dormancy. I was glad to see the needles on my yamadori ponderosa turn to their normal winter shade.
 |
| This lighter green is normal for ponderosa needles in winter. |
And sometime in the next couple of weeks my half-hardy trees will be moved into the mudroom, and the hardy trees will go under their rack in the side yard.
The long-term forecasts call for above-average temperatures for the rest of the winter. In view of that, I've considered leaving my hardy trees out and just making sure they were protected from hungry and inquisitive critters. But a recent blog post by Michael Hagedorn on winter chilling requirements led me to change my mind.
The gist of what Hagedorn says is this (unless I missed something.)
- Plants that are native to the earth's temperate and cold zones need a certain amount of winter chilling, measured in hours at temperatures between 33° and 50° F (.5° and 10° C.) Winter-chill requirements vary by species.
- If a plant doesn't get the hours of chilling that it needs, its growth the next season will be affected; some species won't break dormancy until their chill requirements are met.
- Temperatures below freezing don't count on the plant's internal chill clock. (I have no idea why that might be.)
Once my hardy trees are under the rack, they won't be as much affected by temporary temperature spikes that would interrupt their chilling requirements. So when spring does come, they'll be more likely to break dormancy on something approaching a normal schedule, and then grow well next season. The fabric that covers the rack will also serve to break the wind, and will hold in the fumes of the mothballs I use to discourage chipmunks, squirrels, and other cute-but-destructive little scoundrels.
To see Michael Hagedorn's post on hardiness and winter chilling for yourself, please click here. The post is thoughtful and well-written, and I recommend it.
:-) :-) :-)
