Hardiness Zone Question

[nellie923]

Here in the River Vally in Arkansas, we have had extreme highs and lows lately. Our zone is now officially zone 8a. The winters for the last few years, however, have given us what we call the "arctic blast" of cold temps for several days. Many of my plants, even ones rated for zone 5, have not survived these winters, although the lowest temp for 2023 was 25, but that does not count windchill. I have to assume that the plants are further stressed by extremely hot summers. 2023 had several days of 107. So I'm wondering if the extreme high stresses plants so that many of them can no longer survive 25 in winter? I'm in Fort Smith, which is right on the Oklahoma border, where our weather comes from, unmitigated by hills. I had 4 tri color willows (rated to zone 5), 3 of which are now dead, including two that were well established. It is frustrating to know what to plant for such extremes.

 

[Meadowlark]

...It is frustrating to know what to plant for such extremes.

Yes, frustrating indeed. Those artic blasts really can do a great deal of harm.

I'm well south of you in East Texas and the low during the "polar vortex" of 2023 was 15 deg. F here. I can't understand how you only hit 25 deg F. The only good thing about those blasts here is that they normally do not last more than a day or so and then back to normal.

The extremes are very difficult to plan for.

I use a lot of N-Sulate frost protector cloth, and it does a really good job during those artic blasts. There isn't much I know of that can be done about the 110 deg F days we get in summer...except plant high heat cover crops and build your garden soil.

I use Sunn Hemp and cow peas for those dog days of high heat and build soils while it is too hot for most veggies.

Love the Caddo river valley and on up to Ouachita and over to Hot Springs. Spend a good bit of time there every year. God's Country for sure.

​

 

[roadrunner]

I've had an arctic blast for the past two winters and it killed everything, this last winter we're just coming out of was an exception, finally... Everything lived thru this winter. That's weather


BTW, my zone also got modified from 9a to 9b, but it doesn't mean much to me. I don't care about the average coldest temps, I want to know the all time cold temp and plan for that, so these hardiness zones are useless to me.

 

[nellie923]

Yes, I understand that the zones are averages and exceptions will apply. As for all time cold, in 2024, we hit 3, without windchill factor. (2023 was not as bad with 25 min but 2022 also boasted a low of 3.) USDA map says 0-5 above zero is zone 7, but some plants die anyway. Guess they can't read what is on their tags! I'm shooting for plants that work in zone 5-9 or even 4-9.

 

[roadrunner]

The worst winters for us here in Jax was back in 2009 thru 2011, those winters were not only brutally cold from Arctic blasts, but they lasted for weeks at a time. We've had more Arctic blasts since then, but none have lasted nearly as long as those couple of winters. And I hope I never get those winters again.

As far as Windchill, our cold days are ALWAYS accompanied by a cold NW wind from Canada. If we didn't have wind we would never get below 50 deg down here in Jax. That's why I say that they're building the wall on the wrong border


Here's a news article from California (in 2010) about Lizards falling from trees in South Florida, that's how bad it was and it made national news

Frozen iguanas fall from trees in Florida and come back to life | ABC7 San Francisco | abc7news.com

Frozen iguanas fall from trees in Florida​

By ABC7
Friday, January 8, 2010
FLORIDA
Reptile experts say when temperatures fall below 40 degrees the lizards go into a type of hibernation and their bodies essentially turn off. When the mercury goes back up, the iguanas are revived.

"It's almost like they go totally to sleep. Generally speaking, if it warms up quickly afterwards, they can recover, but sometimes smaller animals will not recover. I knew of a gentleman who was collecting off the street and just throwing them in the back of his station wagon, and all of a sudden as he's driving down US1, these things are coming alive, crawling on his back and almost caused a wreck," said Ron Magill from the Miami Metro Zoo.

Iguanas were introduced to Florida by pet owners and have since become one of the state's most invasive species.

 

[big rockpile]

I remember when we lived in Louisiana.

Main Water Lines froze and busted.

They was worried about the Alligators.

They decided they could no longer grow Orange Trees.

big rockpile

 

[cpp gardener]

Windchill is a ‘people’ issue and doesn’t affect plants since it is a “feels like” calculation.

 

[big rockpile]

Windchill is a ‘people’ issue and doesn’t affect plants since it is a “feels like” calculation.

I don't care for WC on Weather Forecast they spend too much time on it instead of actual temperature.

 

[roadrunner]

I don't care for WC on Weather Forecast they spend too much time on it instead of actual temperature.

You must not be a cyclist

As a cyclist, that's one of the most important parts of a weather forecast that my local weather channels don't cover enough, not just because of the WC factor, but the direction of the wind can cause me to choose an alternate route to my destination.

My local weather usually only mentions the wind as an after-thought at the end of the forecast

 

[roadrunner]

Windchill is a ‘people’ issue and doesn’t affect plants since it is a “feels like” calculation.

It's true that WC mostly affects animals, but it also affect plants, by having a drying effect on the plants. It also cools the earth quicker, since it blows away the heat, much like a fan cools an engine.

The earth may not be a living organism, but it does trap heat and slowly releases it over the winter, but wind speeds the cooling effect up. However, if the WC forecast is below freezing, that does NOT mean that the plants (or pipes) will freeze.

Wind

Severe winds can damage plants and trees. Learn how to cope with and prevent wind damage in your garden.

marinmg.ucanr.edu

Excerpt:

Constant wind pulls moisture from foliage faster than roots can draw it from the soil causing leaves to wilt and brown around the edges. Plants have to work harder to keep from drying out.

Wind effects differ with air temperature and moisture levels. Wind increases the harmful effects on plants of freezing conditions, extreme heat, and drought.