zones do not incorporate summer heat levels into the zone determ

13 years ago

We need to know our heat zone! See below!

The zones do not incorporate summer heat levels into the zone determination; thus sites which may have the same mean winter minima, but markedly different summer temperatures, will be accorded the same hardiness zone. An extreme example of this phenomenon is seen when comparing the Shetland Islands and southern Alabama, which are both on the boundary of zones 8 and 9 and share the same winter minima, but little else in their climates. In summer, the humid subtropical climate of Alabama is about 20 degrees Celsius hotter than the Maritime Subarctic climate of Shetland, and there are few similar plants that can be grown at both locations. Due to its maritime climate, the UK is in AHS Heat Zone 2 (having 1 to 8 days hotter than 30 degrees Celsius) according to the AHS (American Horticultural Society), whereas Alabama is in Zones 7 to 9 (61 to 150 days hotter than 30 degrees Celsius). Users need to combine the hardiness zone with the heat zone to gain greater understanding of what can be grown in a particular location.

Sort by:Oldest

Comments (12)

tropicalzone7
13 years ago
My heat zone is a 6. That means that I get 45 to 60 days of the year above 86F which is pretty close to right during the average year (but many summers are a little warmer than average.
Heat zones are very important in understanding a climate, but the one downside to them is that not a lot of people rate plants by heat zones (or at least I have a hard time finding their ratings). Some drawbacks are that a plant in full shade can handle a lot more heat than it can in full sun and also some more tropical plants will be burnt in the southwest and do fine in in Southern and Central Florida despite the fact that they have similar heat zone ratings (Florida rarely goes too much above 90F whereas parts of the southwest rarely go BELOW 100F during summer days!).
But if a map could be created that combines heat zones and usda hardiness zones, then it could give a pretty good idea of what you can grow in your climate! The map would probably be very similar to a sunset zone, only for the east coast instead!
Good luck!
-Alex
us_marine
13 years ago
I think the sunset zones do include the east coast as well. I thought I have looked at them once somewhere? Anyway yeah the heat zone would be cool. Another example would be San Diego and Miami.
Related Discussions
heat zone map
Q
Comments (20)
That's a fair point. But I would say that the plant hardiness zones aren't all that useful either for annuals (which constitute most of vegetable gardening). That's because the average annual extreme minimum temperature (which is what determines those hardiness zones) is usually never reached. That is, the plant hardiness zones tell me what kinds of trees, shrubs, or groundcover I want to put in, with the understanding that those perennials I put in will survive MANY YEARS. If I plant a 5b tree in a 3a zone, it might survive a year, or two, or three, or five, but it'll eventually get killed. I'm in 8b, which means that my temps can get down to 15-20F, but it has been many years since it has ever been that low here. I would have to say that neither of these zone numbers (plant hardiness and heat) are highly useful, but they do provide some context for the recommendations that are being given in this forum. When I see someone talking about "high temperatures", it really, really depends on whether they are from San Antonio TX or Portland OR, both of which are 8b in hardiness. 100F temperatures are "kinda warm" here in central Texas, while they are "dyin' in the streets" there. I've lived in both places. I know. So with the understanding that neither or both zone numbers tell the whole story, the two numbers do tell complementary things. I'd venture that for advice about annual vegetables, the heat number may mean more than the hardiness number does. Thanks for your astute comments!
...See More
dwarf evergreens for attic-level deck in zone 6a
Q
Comments (10)
Weight shouldn't be a huge issue; the previous owners had a hot tub up there. I doubt the trees plus dirt - even when recently watered - would be more weight than a hottub full of water. It took up about 1/3 of the space on the deck. Does sound like lots of dwarf trees are wider than tall. I presume that one can prune in order to reduce this, though. I believe that the reason we want trees up there is for wind blocking and privacy, as well as pretty. I will double-check, though! I actually wonder if it might be better to look at some other type of plant for wind/privacy/pretty up there, upon reflection. I know we also wanted to avoid plants that would drop their leaves all over everything come winter. We were in fact thinking cheap conifers this year; probably from Home Depot. Does make sense to try that first, especially since we're not sure if they'd make it through the winter! Dwarf alberta spruce may be one of the ones we were looking at at Home Depot; can't recall. I was actually kind of thinking that this was very similar to bonsai. When I was first investigating, before posting here, I was following the many links relating to trees in containers, which led to soil drainage and the other related posts by Al throughout this site. I haven't yet gotten the courage to try to _find_ the necessary ingredients, though. Bonsai mix would probably be easier to find! Foam insulated planters makes complete sense! I wasn't sure what, but figured that there must be some way to help improve the chances for a plant to survive. :) I figured as far as the snow and the mulch, in terms of reducing heat and moisture loss. Garden: yes, well-established. There's two conifers that I can think of offhand, both the same type. I don't know what they are, but they have yellow-green, fairly short needles, and are soft to touch and kind of... droopy? Not terribly helpful, I know. :) Being well-established, I don't yet know where we might be willing/interested in putting in trees that outgrow their pots. As such, I was hoping to not presume that we would be able to do that. Overwintering in the ground might... actually be possible. Even if we don't leave them there, that does sound potentially work-able! Size, I think probably 4-6' or so. Guessing. I really need to go ping my housemates and get more details, clearly. Thank you all! This is certainly giving me lots of think about, as well as specific ideas of what to try. :) Suzanne
...See More
Need recommendation for heat/drought tolerant zone 7
Q
Comments (1)
She needs to go into the TLC on Memorial and ask for Marteen. He is the primary overseer for all conifer orders. He has years of experience with conifer survival in this area. He will shoot her straight on what will make it here and their variety to pick from is impressive. Unfortunately their prices are fairly high as well. I'm currently in the middle this spring and coming fall of putting in an extensive combination of conifers. I'm trying to see how far I can push micro-climating but definately anticipate losses. Our heat is not very conducive to a lot of conifers. mark
...See More
Burning Heat & Monsoon...... Zone 9b Islamabad.
Q
Comments (215)
Thank you, Khalid, for a wonderful show of roses blooming in hot temp. I like your dark-color roses: McCartney rose, Ebb tide, H.Z, Doris.T., and Oklahoma. Alec's Red is known as partial shade rose. Old Garden Roses are usually sold as own-roots here in America. In my experience, floribundas are better as own-root. Floribundas such as Ebb Tide, Bolero, French Lace are very good in acid-phosphatase (producing acid to break down minerals for blooming) .. thus they can root easily & be able to go deep into my hard-clay for winter-survival. I have to give high pH dolomitic lime to my FLORIBUNDA roses: Bolero, Old Port with dark green leaves. The exception is my Kordes Floribunda Deep Purple (ultra-wimpy as own-root) .. some Kordes roses are bred to secrete LESS acid, to prevent blackspots, and folks in alkaline clay California complained that some Kordes roses don't bloom well. My hunch is: if a rose blooms easily, it means roots can secrete acid to utilize minerals in soil, which means it will root easily, and does well as own-root. Per Khalid question: Do you think it will be safe to remove soil from the roots (in the evening), dunk the roots in a bucket of water for some time and plant it at a new place in temps ranging between 90-100*F during day but 80 to 90*F at the time when the rose is being shifted (evening time)? Answer: Yes, it's safe to remove soil from a GRAFTED-rose (Dr.Huey rootstock or Centifolia), dunk that in a bucket of water to get rid of termites, but NOT safe to plant at that high temp., unless you are in wet-season with frequent rain. I dug up roses at 90 F, bare-rooted in a bucket of water, and had to water it 3 times a day, otherwise the leaves droop. I bare-rooted Bluegirl (Dr.Huey-rootstock), then planted in another location. I had to water it daily for 2 months .. before it sprouted new leaves. Thank God it didn't lose leaves being dug up at 80 to 90 F, but it's a pain to water it daily for 2 months. I had seen Dr.Huey rootstock being wrapped in wet-sawdust, with a plastic outer-cover, sitting inside the store for 4 months, yet sprouted green leaves. If you don't have wet sawdust, anything damp & soft like cloth can sub. and the roots can be stored inside for weeks, then plant later when you have time or the temp. goes down.
...See More
tropicalzone7
13 years ago
They do include the east coast, but it isnt really as efficent as it is on the west coast! I think Im in a sunset zone 32 (not 100% sure) which included most of New Jersey down into Maryland, Delaware, and Parts of eastern Virginia. But they have Long island as a zone 34 like most of New England and although summers are kind of similar to New England (especially the farther east you go) the winters in long island are milder and there are a lot of plants that will grow there that wont in most of New England (like southern magnolias and Camellias). All 3 of these zone maps together really would make one awesome climate map though!
-Alex
us_marine
13 years ago
One of the problems I do see with the SunSet zones; at least for my area is that is puts it into a zone that need to be divided further. It also doesnt take into account how many days above 100f!!!
lzrddr
13 years ago
and most importantly of all (for palm growers at least) is zones do not include average daily temperatures. For example, the average daily temperature in my town in southern California in winter is probably in the 50s, while a town in Florida in the same zone (eg. Orlando) has daily averages about 20 degrees higher. Even though it may actually have some colder lows. So you can grow coconuts in Orlando but not here despite both being a zone 9b. Zones do not include humidity, either, another determining factor in what will or won't grow for you (which is why Juabaes do great in my yard, but not in my friend's yard in Orlando). There just is no way to create a meaningful zone system that would accurately help predict what plants will grow where.
tropicalzone7
13 years ago
Very true! Looks like the only way to truly know what will do well in your yard is by looking around your neighborhood and trial and error! And if a plant you like doesnt like your climate, then you just have to protect it and hope for the best!
Good luck!
-Alex
jimhardy
13 years ago
About a 120 days of 80 or higher here this year made up for any
damage cause by last winter,I think we had almost 90 in a row of 80 +.

It wasn't even a hot summer!
wxman81
13 years ago
On the border of heat zone 4 and 5 here, so that's about 30 days a year of 86+. Normal highs hit 83F here or so in mid July. Perfect trachy growing weather in my opinion.

Now if I could do something about my zone 5b and turn it to a 7b and maintain heat zone 4 or 5. :)
stanofh 10a Hayward,Ca S.F. bay area
13 years ago
Well,even Sunset doesnt seem to be in a rush to update its flawed system. Hayward Ca is not the same kind of zone 17 as San Francisco..much less fog,quite a bit warmer in summer than San Francisco..colder lows in winter-darn, can't have everything.
I think they could do a z17 as in San Francisco a z17b for the cooler farther north like Eureka and 17c for the southern and also patches of warmer northern SF bay area.
us_marine
13 years ago
I think the chill factor could be a useful tool as either
part of the general description or as a side mark with other climatic stats.
Another possible thing they could do is add transition zones.

LOL now its getting complicated!
brooklyngreg
Original Author
13 years ago
True,
Zones do not include average daily temperatures and I agree they should have some transition zones for plants like palms that include it.
garyfla_gw
13 years ago
Hi
Zone designations couldn't be more than a general indication could they?? I'm at the northern edge of 10
but live quite close to the sea so during cold fronts the low is often 10 degrees above areas 10 miles inland
Same is true for summer . Cold is a LOT more noticeable than heat though lol
Then there is the variation from year to year . This year for example set a record on daytime highs being 10/15
degrees below normal. So have had as many as 5 years in a row in 11 and 3 in 8 lol over a 30 year period. the rest fell into 10. This year will be a 8/9 at best lol gary

zones do not incorporate summer heat levels into the zone determ

Comments (12)

tropicalzone7

us_marine

Related Discussions

tropicalzone7

us_marine

lzrddr

tropicalzone7

jimhardy

wxman81

stanofh 10a Hayward,Ca S.F. bay area

us_marine

brooklyngreg
Original Author

garyfla_gw

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US

zones do not incorporate summer heat levels into the zone determ

Comments (12)

Related Discussions

brooklyngregOriginal Author

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US

brooklyngreg
Original Author