USDA's new Plant Hardiness Zone Map reflects warmer winters

And then there are "chill hours"

http://www.ehow.com/how_7359408_calculate-chill-hours.html

plus daylight hours also influence some plants.

LOL, can't mess with my head. You can't get in there. Too thick. No, I know what you mean and I agree with whoever of you said it is best to go with your knowledge of where you live. Just like 1lisac said. All of her area is not flat. Hills make a big difference. I.e. I am about 200 feet higher than the highway below, and I have nothing but ice and the road and around it is bare. It will snow all around my house and either not there, or rain there. Just that much elevation makes a difference.

And a couple hundred feet the other side of the highway is a large river. So, like whoever said, that makes a difference too. Being near the water. Sometimes warmer in areas next to it and maybe colder in other place next to it.

Texas grows tulips...

Do they last forever without digging them up ?
I have some I planted when I moved here in 1982. Still bloom beautiful every year.

Nope ~ and horseradish doesn't like us any better than the rhubarb does.

Too bad, hr is wonderful.

Yes... I love it. Good thing the grocery store stocks roots and processed. But I am probably their only customer. lol

I've never grown tulips, but I seem to remember reading that some come up year after year, and others don't.

We couldn't grow daffodils when we lived in South Florida. It was one of the first things I planted when we moved here.

So Podster, you buy the root? What do you use to grind it? We use an old food processor that we only use for that purpose. I guess the longer you wait to put the vinegar in it, the hotter it gets. The vinegar stops the heat. Is that what you understand?

We ground about a pint of it last fall but it doesn't last long. We use a lot of it when it is fresh like that. I have read that after a couple months it starts losing it's potency. But ours never lasts that long.

Yes. I understand that is the purpose of vinegar also.
I have an old hand crank grinder that can be set up outdoors, prefer a breezy day too. lol
I have also bought root to plant as well as tried plants. Not enough success to write home about.

The hardiness zones are average winter lows. To me that means that around half of all wnters will not go that low, and around half will goo lower.

I always wondered how valuable a number was, that meant around half of all winters would kill your plants?

I wish they published a "10%" hardiness map, or even "5%". Meaning, how many winters out fo the last 100 went below the given temperature. Then you might expect, on average, to only have a 5% or 10% of losing those plants each year.

But I think many of us "push their zone", and then the Zone number just tells us HOW overoptimistic we're being.

With Salvia & Penstemon, I "plant and hope". They might over-winter, they might reseed, and mulch should help as long as I don't put it down too soon.

Yes I think you are right Corey. About losing the plants. I don't do bad with zone 4 plants, but don't know when they start changing the zones on the plant labeling. How do you know what zone it would be using the same ones you have been going by?

I never figured out how to mulch too soon. I guess you are suppose to wait until it freezes once and then mulch or something like that. I think Ed Hume (do you listen to him? In Seattle) used to say to be sure you give them a lot of water before it freezes. You would think the roots would freeze.

Don't know, too many ideas out there.

Podster, horse radish must be like Rhubarb, it needs the cold winters. My sister has one area right next to her back deck where the Horse Radish comes up every year. Last year her son dug down so deep to get it out and it still came back. I tried to grow some in a big black nursery tub so I could contain it, but I must have put too many plants in it cause I didn't get any big roots. Just fibrous roots.

So, I get some from my sister each year.

Sounds like a bargain... especially when your nephew does the digging! lol

Yeah, but he was trying to dig it out to get rid of it. They may spray it next time. LOL

What they need is a map that includes designations for the standard deviation. We may have the same "average winter temperature" or the same "average low temperature" and some of the Western states, but trust me it isn't the same at all. 22 and 78 may average out to the same number as 42 and 58, but when they occur two days apart there's a big difference! I really wish we could adopt something more along the lines of the old Sunset zones, which distinguished between the areas with more stable winter temperatures and those with more variable weather.

The real killer here is not even the cold - it's the timing. Many of our "tender" crops can take some very cold temperatures when they are dormant, but not once they have started into active growth.

-Rich (who spent part of the afternoon looking at dead leaf buds on my pomegranates and loquats).

Let's get back to Zones on this thread.
The Zones are for the hardiness of perennials. Has nothing to do with average low temps or how Florida compares to western states. Doesn't mean a thing as far as when to plant annuals.

>> The real killer here is not even the cold - it's the timing.

I agree with that, especially "speed". A gradual descent to "X degrees", that gives plants time to go dormant during "cool" weather, will kill fewer things than a rapid drop from "warm" to "X minus 10".

And "cycling" is bad, such as we have for the last half of winter and all spring: alternating warm and cool spells.

Jnette,

>> I don't do bad with zone 4 plants, but don't know when they start changing the zones on the plant labeling.
>> How do you know what zone it would be using the same ones you have been going by?

Not a problem for me, becuase I hardly ever buy plants, I only grow from seed. I guess the exceptions are a very cold-hardy bamboo (Fargesia rufa), a peony that my SO urged me to bring home from Safeway, and some flats of Pansies that turned out to be more cold-hardy than I dreamed they COULD be.

Mostly, plants that survive come as a surprise to me.

For seeds, I look up the name and variety (or, for trades, look up a name that's as close as possible to whatever name it was labelled with, and guess. Peopele's experience as expressed in Plant Files comments seem to range + / - two Zones from whatever theoretical Zone is claimed by someone for that variety. Some of that is micxroclimate, some is how people care for plants, and some is the differene between (for example) Texas Zone 8B and WA coastal Zone 8b.

And my guess is that anything other than a Propagation-Protected, vegetatively-multiplied cultivar has enough genetic variation within it's population that individuals within a variety probably DO vary by 10-20 degrees F in their cold hardiness (or immunity to suddeness or spring cycles).

So I go by how an individual plant does in my own yard. Some die that I "should" have expected to live, but some live that "should" have died. If I ever collect seeds from the survivors, they may tend to reflect slightly more cold-hardy individuals.

When I actually pay more than a few dollars for a plant, I try to "be safe" by about 20 degrees. My "average" Winter low may be 15 or 20 F, but I looked at the 50-year historical data for my local weather station, and saw two years with a few days in a row that went down to 0. I seem to recall they occured in the last 20 years.

But zones and Zone Maps are exactly what I'm talking about. In most of the East, the zones are frankly wrong. You can buy plants that are "hardy" in your zone and have them die in the first winter (or the second, or third...) because they start growing during warm spells and get cut back by subsequent hard freezes. Budding and sending out new growth drains perennials' energy reserves, and they can only send out new growth so many times before they run out of stored food (or new buds). Often - especially in young plants - that is ONE time.

The current perennial hardiness zones, the way they are drawn up and described, don't work here. They are often worse than useless, because they encourage novice gardeners to plant things that can't possibly survive, and leave them thinking it was something they did wrong. Well, it was: they trusted the zone maps.

There have been other attempts made at zone maps that took into account the extreme variability of weather in the East compared with the rest of the country. Sunset did it, with far less data and advanced technology than we now possess. With the vastly greater volume of historic weather data now available and far greater access to computing power, the job could be done much better IMHO.

-Rich

We had a record-breaking cold spell a year ago. We moved from Zone 5 to Zone 4 for about a week.
And our "Average Last Frost Date" is a really rough average - it can be way off either direction in any given year.
But I appreciate the department of Agriculture for trying.