I’m not really happy to see Southern Missouri changed from 6b to 7a for the most part. Yes we are more or less warmer than we used to be by a little bit. However, we hit -12 a few years ago. 3 out of the last 5 years we’ve hit negative temps, twice getting below -5. Average Joes aren’t going to pay attention to that when ordering perennials. They’re just going to see what our zone is and buy plants accordingly, thinking since we’re 7a everything will survive just fine. I foresee a lot of people wondering why in ground figs, Asian persimmons, etc. are dying off when the zone map said it would be fine. I wish the zone map had an “extreme low in the last 10 years” note to go with the zones so people understood more easily what plants are more likely to survive a polar vortex.
same here- same situation. people in my local garden page on FB are already asking about planting figs in the ground. they are shocked to hear even a Chicago hardy needs a whole lot of protection here, even heat too. a lot of things that are zone 6 (in-town zone mostly) die in winter here, I try to err on the side of lower zoning personally.
the big box stores will be happy at all the “perennial zone 7” sales I guess?
Spokane weather is more continental (inland) than Puget Sound cities (coastal). Hence the larger span of temperatures for various statistics.
it makes sense with the Canadian Rockies and the Pacific vying for dominance there, youd tend to see some pretty wide swings. There is similar though different tumult climate wise here in New England- coastal systems colliding with southerlies and westerlies make for famously unpredictable weather. Also said to be much of the reason Mt. Washington has such high winds: 100 mph+ every 3 days on average with the highest sustained winds anywhere on Earth at 231 mph.
climate is interesting stuff. i wish i knew more about it. so much of it os impossible to know. chaos theory was created by study of weather, after all. its really stochastic- ordered chaos. nowadays with our devices being so powerful, its a lot easier to visualize whats going on weather-wise. One of my favorite things to do is check out the weather radar and zoom out so that I can see how the different systems are interacting. its so much more informative than a network news meteorologist flailing their hands about wildly while spewing some nonsense about an upper level disturbance meeting a mid-level trough (or somesuch)
Have you checked out the wind map, and all the layers you can enable on that? It’s really fascinating, probably my favorite tool for visualizing weather systems or ocean currents.
For example, this shows the wind at 250mb (the jet stream) with the shading being relative humidity, so you can see how it brings moisture:
And here it is in ocean mode, animating ocean currents with the shading representing the temperature anomaly:
The “particulates” mode is also good for wildfire season.
I use Ventusky a lot. Fairly detailed live data.
It is fun watching hurricanes and tropical storms approach on their live air pressure map.
I can almost guarantee that a variance or standard deviation map was created as part of the procedure, or at least a variance surface that could be used to make one. It would be much less useful to use by itself, as you need the average map and a basic understanding of statistics (and the limitations thereof) to make much sense of it. They mostly would have used it for qa.
Almost sounds like people doing technical analysis on stock prices, haha
Voicing similar concerns that other people in this thread have, and adding some of his own take, I found this discussion from Tony Avett to be pretty solid. He touched on a lot of nuances that a worth bearing in mind.
Street cred: this dude grows hundred of cacti, dozens of agaves, and even freaking lithops outdoors, unprotected, in ground, in NC
Probably why he has grey hair!
He probably is the same as I am with my precious tiny banty chicks in cold weather. My wife worries I will try to bring some in the house to bed to keep them warm.
I didn’t find the interactive map that you can zoom in to neighborhoods mentioned in the video, just a zip code search.
It stands to reason for anyone who has lived in one spot for 10+ years that the hardiness zone is just a guideline and not a guarantee that your choice of plants and trees will survive.
I think the biggest disconnect that we are stuck with is the insistence of linking hardiness zone to chill acclimation. I think it’s apparent they often don’t have much to do with each other. Seattle and areas close to me only a few hundred miles from the gulf coast are in the same hardiness zone but Seattle gets ~3000 chill hours a year while down here we are on the range of 300-600.
Haha, in some ways, he’s the opposite. I forgot how many plants he claim’s he’s killed, but something like 50,000. Gotta kill a lot of plants if you’re going to find what crazy exotic is hardy and under what conditions.
Often quite a bit more than that! In my yard we’ve had 700 chill hours just in the last 30 days alone…
In any system that gives negative numbers for temps warmer than 60°, I end up in the negative for the winter.
So yeah, definitely not a one size fits all attempt to quantify chill acclimation.
After next springs grafting I’ll have enough wood on trees to find out what those often wildly different chill requirements posted by nurseries and the like actually mean for me in my locale… Or at least a few years from now as the grafts need to mature.
That was a great little synopsis, and I agree he covers nearly all of the caveats to “hardiness” and the construct of “growing zones”. Amazing to see those Lithops there. Pretty cool!
For the record, I would take issue with two of his observations:
- “Everything under snow is at 32 degrees.”
Maybe he didn’t exactly mean this, but Ive heard it elsewhere too, and its most certainly not the case. If its -5 degrees and snowing, what temp do you suppose the snow is? It is the case that snow is relatively speaking a very good insulator. According to this article in the Journal of Light Construction, it has an r-value of 1 per inch, about like wood. So snow cover, especially continuous snow cover starting early in winter does prevent fluctuations of temp to a large extent.
- “Wind affects conifers but not deciduous trees. It affects only the needles, not the branches.”
Maybe this is true at NC levels of cold and wind, but it doesnt pass the sniff test for me based on my experience and what Ive observed. According to this chart, -13 F degree air can only hold 1/4 the amount of water as 14 F air.
Thats about the difference in water capacity between 50 F and 14 F, as well as the difference between 104 F and 59 F, and those of us in temperate climates all know how qualitatively different those temps are humidity wise. And thats max capacity. Winter air may only be at 50% RH much of the time. Really cold winter air is hella dry, and any plant if its alive has water, even if its only the water inside its cells. Even without wind, desiccation is an important source of winter morbidity. Often as not, when the winter wind is blowing, it is both very cold and very dry. Ive seen large amounts of snow and ice sublimate under these conditions. Those same conditions are sucking the water right out of plant cells, foliage or not. In fact, Ive heard wind exposure cited as a prime factor in what regions and habitats are dominated by coniferous trees. Conifers, being more tolerant of exposure populate the upper elevations of nearly all temperate mountains, for example. Conifers have waxes and resins that help prevent desiccation, while a common feature of many deciduous tree barks are lenticels, which are literally pores. An example of a deciduous tree with very waxy bark (and also lenticels) is white birch, which coincidentally also happens to be among the handful of most hardy deciduous trees.
Agreed on all three points.
I don’t know to what extent he knows this and would agree but is glossing for the sake of the video, or not, or if he’s being hand-wavy on these points given his location, or is straight up wrong but I guess that’s all neither here nor there–These are good points to consider, especially for people in less mild areas than NC.
Astute observers may have noticed that this was surely impossible, and sure enough my PHP code for calculating chill hours made a fatal NASA-esque error (forgot to convert 45°F to 7.2°C, so was calculating all hours below 45°C instead). With the bug fixed, the chilling hours from Nov. 1 to present in my yard are a little more believable:
Report start: 2023-11-01
Report end: 2023-12-06Highest temperature in range: 62.54°F (2023-11-04 13:35:46)
Lowest temperature in range: 28.26°F (2023-11-28 04:06:19)
Freezing hours: 35.2
Chilling hours (32°F to 45°F): 332.4
Utah chill units: 568.9
And perhaps a more interesting date range, the amount of chill we accumulated last winter (including some fall and spring dates where lots of chill was accumulating too):
Report start: 2022-11-01
Report end: 2023-04-30Highest temperature in range: 77.52°F (2023-04-29 15:44:53)
Lowest temperature in range: 17.04°F (2022-12-22 06:49:06)
Freezing hours: 292.5
Chilling hours (32°F to 45°F): 2392.3
Neutral hours (45°F to 60°F): 1473.2
Warm hours (60°F and up): 65.6
Utah chill units: 3050.5
Agreed…give me the current radar and a map of the barometric pressure (and a temperature point or something) and I don’t need the loud mouths nor the cute skirts on tv.
Wot??? Weathermen in cute skirts??? What is exactly your target market there?
Possible 720 chill hours in 30 days.
But over that timespan, western PNW sneaks out of chill hour range for hours here and there.
Portland set an all-time (1938-to date) month of December daily high of 67F earlier this week.
Overnight low of 57 degrees broke previous maximum daily low for the date by about 10 degrees.
Right now (noon) the thermometer reads 45, so back to the chill zone for awhile.