Hardiness zones and climate change
John Donovan
7 years ago
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Comments (13)
NHBabs z4b-5a NH
7 years agohomegrowninthe603
7 years agoRelated Discussions
Zone change due to climate?
Comments (11)The USDA hardiness maps, in my opinion, do not really work well on a detailed level. Sure, they do accurately describe general patterns of hardiness, but to claim that some parts of Massachusetts and some parts of Mississippi share the same zone for vegetation (zone 7) is ridiculous and is simply a reflection of the way the zone maps are created. These maps focus only on the lowest temperature typically reached in winter. Zone 7 means temperatures generally don't fall below zero. And yes, for Boston and the coastal areas of Massachusetts, that is the case during most winters. Similarly, zone 7 areas in the upper south also experience similar low temperatures. BUT....and this is a big BUT....the duration and frequency of very cold and windy airmasses in winter is MUCH higher in our area than in the upper south. So while southern areas will have one or two mornings during winter with temperatures in the 0 to +10 range during a cold wave (usually with clear skies and calm winds) they warm up rapidily and that is the end of it. We, on the other hand, have repeated incursions of very cold air, often on strong winds, during the winter. And that makes a huge difference, particularly in late winter when the sun angle is high. Just imagine this: Every winter morning could drop to +1 degree F and that would technically be a zone 7 winter! BUt few if any zone 7 plants could withstand that. And this past winter was also, technically, a zone 7 winter because the temperature never dropped below zero in most areas in southern New England. But the persisent wind and cold of February, without snow cover, damaged or killed a lot of plants that are normally reliable in zones 5 or 6. I have even seen dead zone 4 Arborovitae! So, don't believe anything you have been told about zone drift....See MoreNew Climate Normals; USDA Zone Changes
Comments (4)Well, you are partially correct. The climatologists are predicting generally warmer and wetter weather. They are also predicting more extreme events. So more droughts like this one, more floods like the midwest has, more blizzards like this last winter, etc. From what I can tell, we are only about 1 degree warmer here, the problem is the extra icemelt in the arctic that will add to the atmospheric moisture and cause more precipitation overall and generally crazy extreme weather. I'm not really looking forward to the warmer summers but the added precip will be nice. The lady I heard on the radio was saying that tornadoes are the one weather event they aren't sure on. They have no idea how the climate will affect our tornadoes. I'm going to bet on larger ones since we seem to have had more of those in the last decade or so. If things keep going like they have been, we may have to have two distinct gardening seasons, with a break in July and August....See MoreHardiness/Climate zones
Comments (5)Climate takes into account a fair number of things besides winter temperature. How much rain falls and when, and the difference in temperature between summer and winter are important. Almost the entire eastern half of the country is simply variations on one climate, with arbitrary distinctions between warm and cold, and between wet and less wet, and dry. Sunset zones become important in areas where you can have two zone 8's near each other. One has normal summer highs of 75, and the other has normal summer highs of 105. Obviously plants are going to have opinions of which they prefer....See Morejust moved my zone
Comments (16)It's all about averages. You can't argue with averages. As I've said several times, we tend to abide by the average date of last frost when we plant out, knowing full well that we might still get a frost after that date. Should we toss those frost dates in the trash because they might not be quite right? There is a nice explanation of the new map at https://www.ars.usda.gov/news-events/news/research-news/2023/usda-unveils-updated-plant-hardiness-zone-map/. Not at all clear that those maps are intended for trees. I guess it comes down to definitions. Maybe USDA should be more forthcoming about these maps not being appropriate for orchardists as opposed to "gardeners and growers". Let's face it, at least for a home gardener, for crops that aren't trees or large aged vines, it's all about protection. What are the chances that you'll need protection to preserve your crop? When my temperatures dipped a zone or two below my own in the last few years, it just took a tarp or two to protect. Same with when I get an unexpected frost after planting out frost-intolerant summer veggies. That's because the cold snaps were sudden, and over soil that was a lot warmer. Certainly, if you have weeks of intolerable cold, you have a real problem with survival. For those with acres of crops, yep, you just lose the crop. But there are many reasons why you might lose a crop, and abiding by zones is just playing the odds of averages. Farmers are always playing odds. As noted in the explanation I pointed to above, the USDA Risk Management Agency refers to the map’s plant hardiness zone designations to set certain crop insurance standards. The risk here is assumed to be one year for one crop rather than many years for survival of an entire tree. But yes, the word "thrive" here applies to a yearly crop, and not to long term survival of trees....See Moremad_gallica (z5 Eastern NY)
7 years agodeanna in ME Barely zone 6a, more like 5b
7 years agomad_gallica (z5 Eastern NY)
7 years agodeanna in ME Barely zone 6a, more like 5b
7 years agotimbz6
7 years agotimbz6
7 years agotimbz6
7 years agodefrost49
7 years agospedigrees z4VT
7 years agoPersimmons
7 years ago
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