What is Your New Gardening Zone?

[bboomer]

How will it effect your gardening decisions? Madison, Wisconsin went fro 5a to 5b!!

https://apps.npr.org/plant-hardiness-ga ... =43.087815

[Mark_Thompson]

viewtopic.php?t=4913

[worth1]

Twilight zone.

[PlainJane]

Still listing me as zone 9A but I believe we’re a solid 9B.

[JRinPA]

That is only minimum temperature expected over the coldest part of winter...it is for trees and perennials and the frost line for fence posts. I use it some for gardening, probably too much, but 6B or 7A doesn't change the last frost date, or number of freeze/thaw cycles. Latitude is more important. If I try to put out plants in 7A PA at the same time as they can in 7A Virginia, I will have dead plants. The sun will ALWAYS be stronger to the south, right down to the tropic of cancer.

So, how will affect me? Well, basically I have to be more careful not to plant too early, just because some chart says it is safe to plant in 7A.

[Tormato]

Hardiness zone has zero importance as to growing annuals. Whether it gets to 20 degrees or 20 degrees below zero, each will kill the plant. For perennials, it can matter, as dormant plants may not survive a severely cold winter. But, it looks like most places have new zones with warmer lowest temperatures.

Last frost early in the season, and then first frost late in the season is important, with many places potentially getting longer growing seasons. Most listings for those frost dates means there is a 50/50 chance of a damaging/killing frost happening on that date.

Heating degree days is another important factor, rarely mentioned. In my opinion, the last frost date map on some seed packets, helping to decide when to plant, is much better info than the hardiness zone info.

[WoodSprite]

Ditto what JRinPA and Tormato said. But in central PA, I went from 6a to 6b.

I’ve always been cautious about my plant out timing, preferring to wait longer than some others near me to minimize chance of losing my hard work or setting plants back with cold weather. Today is actually my goal plant out day for warm weather crops but I’m going to wait a few more days due to some predicted nights in the 40s, a lot of rain and possible hail. However I did direct sow my beans and cucumbers about a week earlier than normal because our temperatures have generally been warmer than most years.

The hardiness zone change won’t matter for the veggies and flowers that I grow. It’s only a small change.

[karstopography]

My location got bumped from being literally on the line, as far as I could tell from the old maps the line split my house in two, of 9/a - 9/b to solidly within 9b. 9b moved inland fifty miles or so. The change in designation is essentially meaningless here. Three of the last four winters here have had zone 8 cold. I’m not disputing the data for the hardiness zone changes or the changes themselves, but ultimately, the weather isn’t bound by some USDA construct.

In theory, if the expected minimum temperatures reflected year in and year out 9b type of cold going forward, then citrus would be a much more likely and successful enterprise hereabouts since many varieties of citrus handle 9b cold well, but 9a cold is much more into the danger zone for many varieties and zone 8 cold is deadly to them all. We shall see as my dad planted more citrus after our last bout of zone 8 cold wiped out the nascent grove planted out after the previous zone 8 cold wiped out the previous nascent grove that was planted out after the first bout of zone 8 cold wiped out the decades old grove of very large and productive citrus that thrived for some twenty plus years all while we were on the line of 9/a/b. Mom and dad’s house and citrus trees are 100 meters south of me so maybe they have been in 9b all along,

[DriftlessRoots]

I’m in the Madison area and have always treateded it 5a or 5b depending on microclimate. In that sense it hasn’t changed much.

[Tormato]

Irregardless of any new or old hardiness zone designation, my extreme winter weather has changed over the past 50 years.

Now, a typical winter has a low of about 0 degrees, with about every 10th year having an extreme of 15 to 20 below zero. Previously, about half of the years would have a low of about 0 degrees, and the other half would be about 10 below zero. So, now most years are milder by about 10 degrees, for the absolute low temperature of the year. But, the extreme years are 5 to 10 degrees colder than the previous absolute low temperature of the year.

What does it mean to me? When selecting hardy fruit trees, I hopefully have several years to have them mature. Some nurseries say that a mature tree can handle about 10 degrees colder temps than a young 1st year transplant. In any case, the tomatoes are a long, distant memory.

[karstopography]

These days, I’m gambling on the last frost or freeze of the year being earlier in the year. The last frost of the winter is highly relevant to my tomato growing efforts. Seems like we had a stretch of winters in the 1990s into fairly recent times without many frosts or late frosts, but prior to that March freezes were pretty common. If it is 15° or 30°, the tomatoes don’t care, they will all be dead at either temperature. The crystal ball for when is the last frost is the most valuable one.

With Houston ever expanding and sprawling to my north, that huge input of manmade heat helps temper chances for a late in the winter season, the radiational cooling type of frost as just enough of that heat leaks my way. Sandwiched between the ever enlarging hot city and the Gulf of Mexico, there’s less chance of an accidental type, whoopsie, but still devastating to tomatoes March frost. However, when polar air breaks loose and decides to head our way, the big city is powerless to overcome that kind of cold. Those polar air masses, so far, fail to come this way in March.

[SpringtimeInTheBag]

I was 6a. I'm still 6a. In the 1990 map without address level granularity I'm maybe 6b but close to the 6a line. Essentially it's been 54 years with no real hardiness zone changes here. There's been some shift on the first and last frost data that affects things. That's a whole different issue than hardiness zone.