New USDA Hardiness Zone Map

[digitS']

After using the same one for over 20 years, the USDA has unveiled their new map. Instead of data from 1974 to 1986, this includes winter weather temperatures from 1976 to 2005:

[url=https://planthardiness.ars.usda.gov/PHZMWeb/Default.aspx#]Plant Hardiness Zones[/url]

You may notice some changes to your zone designation. The site is much clearer, you can do a zip code look-up that's USDA official and all you need to do is click on your state to get an up-close view .

Steve

[lily51]

Thanks for the update. looks like most of Ohio is now zone 5a except our county which is half zone 5b

[GardenRN]

Dang, I couldn't be more split on 7a and 7b. I guess it doesn't matter much, I know what the weather is like. I think this is probably more accurate. I always wondered why they said my avg last frost date was May 1st but I knew it was earlier than that. I'll associate myself more with 7b.

[gixxerific]

I went from 5a to 6b.

I'm screwed, I have no idea what to do now. I may just not plant this year, I just don't know where to begin now.

[DoubleDogFarm]

I went from 5a to 6b.

I'm screwed, I have no idea what to do now. I may just not plant this year, I just don't know where to begin now.

You Funny, you funny man! Ha ha!

Eric

[PunkRotten]

I am 10a. One site said I was 8b but disagreed. Another site said I was 9b.

[shadylane]

According to, I have went up in the zoning map from 5a to 5b. I wonder what the climate controll areas will be perhaps 6b or 7a. This may be a good time to do some plant testing just to be on "Know the Answer" side. Interesting.

[Skian]

Does anyone know why the decided to do this?
Daylight Saving Change = Zone Change
Climate Change = Zone Change
Just wondering?

[applestar]

Made this a sticky

[jpr54_]

I am now in 11a

[DoubleDogFarm]

[Dixana]

WOOOHOOOOO! I am in zone 5 now!!!!!! So exciting for me as I can plant a lot more things now!

[skiingjeff]

This is great! I was always between zone 5 and 6 but this new map is very clear that we're zone 6a!

[stella1751]

WOOOHOOOOO! I am in zone 5 now!!!!!! So exciting for me as I can plant a lot more things now!

Ditto! I'm going to ignore what it's really like out there. No more zone 4 gardening and planning for me. I'm a zone fiver now!

Er, um, does this mean I can grow orange trees?

[cynthia_h]

Have held off, but am feeling so awful today that I think the USDA Hardiness Zone Map is gonna get it.

First of all, the Hardiness Zones only tell us what will survive the winter. Many people do not garden in the winter, so the Hardiness Zone plays little part in selecting veggies to grow. More to the point are data like length of growing season, dates of first/last average frost, annual precipitation, and so on.

A climate zone system, to be of practical use to gardeners, needs to account for these factors, as well as latitude, prevailing wind (makes a real diff. in humidity), elevation, etc. Which is why I always talk about the Sunset climate zone system.

Although for some reason the USDA has assigned my zip code to a different zone than traditionally it's been assigned to (and I had to do a Captcha code to get this precious nugget of information! ), my own experience gardening in this zip and in a zip 6 miles due south over the past two decades--the span of time the new map is based on--directly contravenes the winter minimum temperatures listed for my new zone.

The new zone says my winter minima are between 30 and 35 deg. F. Bullfeathers. Ha! My own memory, as well as newspaper stories, agricultural disasters, and other third-party sources, provide these proofs of different minima within the relevant 20-year time frame:

1991--late December; hard freeze (20-25 deg) for several consecutive days. Many well-established plants die throughout northern California; the Central Valley citrus crop is destroyed.

1998--A short hard freeze (25-28 deg); my normally outdoor cymbidiums, hardy down to 28 deg, are brought into the house for four days.

2002--January; even the snails stayed hidden wherever they hide, and there were a lot of killed rose canes to be cut off in the spring. Approx. 25 deg.

2008--January; more crop damage, and my jade plants suffered some damage. Approx. 25 deg., had to run supplemental electrical heater downstairs.

My Sunset zone hasn't changed at all: "In a 20-year period, the lowest winter temperatures in Zone 17 ranged from 36 to 23 deg F (12 to -5 deg C). The lowest temperatures on record range from 30 to 20 deg F (-1 to -7 deg C)" (Sunset Western Garden Book, 2001 7th ed., p. 48).

And this is a comparison of the hallmark "hardiness" temps of my "new" USDA zone vs. those of my Sunset zone! Poor application of research; the USDA map strikes out, folks.

Cynthia H.
Sunset Zone 17, USDA Zone 9 (first, last, and always, it seems like )

[jal_ut]

Er, um, does this mean I can grow orange trees?

Ummm, Nope! I doubt if you can even grow a peach tree.

One never knows though, I have two small 3 year old peach trees growing. Even got one peach off one tree this year. It has been my experience in the past that a peach may grow here for a few years, but then we get one of those winters when the temperatures drop to minus 20 F and you can kiss it goodbye.

[digitS']

I wonder what has happened to Stella, James.

She was around here so regularly right thru April then . . .

. . .

Steve

[Albert_136]

I just go to Google and key in ~ USDA hardiness [zip code] ~ and my zone just appears, no longer any need for squinting at a map.

[Chrome might just take me there, I may not even need to go to Google, perhaps, ... ]

[PaulF]

Arbor Day Foundation has issued a new hardiness zone map a couple of years ago, NOAA, National Oceanic and Atmospheric Administration, will issue its maps very soon, and the USDA will be releasing another zone map in the near future. The USDA usually waits for a ten year period for new maps, but they say the weather patterns are changing faster than in the past. The USDA uses a thirty year average of nighttime lows as their base. It is more for what will and can live in an area year around rather than seasonal gardening.

What may change are start times for growing annuals and length of season for annuals. My zone has changed from 5B to 6A, but over the years last frost and first frost has given me a few more weeks of growing season. Gardeners always try to push the limits and get more time, so we just haven't noticed the change.

[Gary350]

What good is hardness zone? Map shows I am in zone 7a but that is wrong it almost never gets 0 to 5 degrees here. It is very rare to get below 17 degrees that puts me in zone 8a. But past 2 years have been exceptionally cold down to 6 degrees. 40 years ago it was down to -17 for about 2 weeks. I don't see that zone has anything to do with plants. What a person really needs to know is when is first frost and last frost. Our last frost is about April 15 to 20 and our first frost is about Oct 25 to Nov 7. Often we have crazy 80 degree weather in Feb for 1 or 2 weeks. People should learn their own weather pattern where they live zone means nothing. I have seen a cold freeze and frost May 15 that really screws up a garden 1 month after the typical last frost. Who ever made up zones must have been smoking some good weed.

[applestar]

When gardening, it’s true that you absolutely need to know the approximate first and last average frost dates, and they are not directly related to Hardiness Zones, but Hardiness Zone is also relevant for other reasons.

Hardiness Zone is exactly what the name implies — it indicates “winter hardiness” and is intended to differentiate which plants tend to be able to survive the winter. There are annual differences and borderline plants need/can be helped by adding a little winter protection — mulching, covering, etc. it also helps to know because plants that will become rampant weeds could be planted where they are not winter hardy to enjoy during the growing season and be merely winter-killed. It is also a good idea to buy locally adapted nursery plants.

There are food crops that are considered fall-winter season in warmer winter areas that simply cannot be grown where the winter low temperatures get too low, but some clever people have figured out that it’s possible to grow them double-protected by covering with fleece under high tunnel.

I tend to think in terms of winter survival from the freeze, but there are also plants that NEED certain amounts of cold dormancy — so there are plants that will not survive or fruit where the Zone is higher/hotter than its Hardiness Zone range. e.g. Sugar Maples grow well 25 miles north of here but not here (same for White Paper Birch).


Knowing the local weather patterns is important as stated. Because the zones are marked in broad sweeps across the map, it’s also important to know the local mini-climate surrounding your garden — urban heat pockets due to hard scape and population density, slope of the land, forested vs unforested, waterways, even underlying geological influences can create local differences — this is also true of frost dates. e.g. My MIL lives 23 miles north of here, but her last spring frost is 2 weeks earlier, and plants that won’t survive the winter in my garden without extra protection can survive in her garden.

My area is close enough to the Pine Barrens where the deep sand actually creates effects that lower the local temperatur in a vast enough pocket to affect the weather and climate, so even though my own soil is clay, my garden is affected by the general Pine Barren’s weather effect. I have also noticed that the weather systems which typically move from southwest to northeast are affected at the Delaware River — so we don’t usually get the deep snow winter cover that could make the critical difference in overwintering survival of some plants (or extra rain in the summer for that matter).

[applestar]

Jelitto Perennial Seed | Plant Hardiness Zones
https://www.jelitto.com/Plant+Informati ... ess+Zones/

[imafan26]

This map has been around since 2012, but most of the seed packages and books are still using the old zonal map. It is good that it does cover more micro climates, but for most people it probably won't change that much about the way they garden. What I found to be more important than the zones are the temperature ranges. With the increases in global warming over the last 3 years, I might have to consider upping my zone based on temperature.

I have always looked for heat and disease resistance since that is what is needed to survive scorching temperatures. It means that some varieties that many of you grow, I could never grow anyway. But, some of you may have to consider growing more heat resistant crops as well.