Heat Zones, or, Why Can't I Grow PNW Plants in the same Zone?

14 years ago

Bluesunflower asked about the effects of sun on her roses and other plants. Here's the best explanation I can find.

Kathy and others in Texas, Annette and Libby in the Pacific Northwest and I are all in zone 8, which means our minimum winter temperatures are similar. Zones only address winter's cold.

As shown by the heat zone map, in summer, the Texans and I experience from 120 to 150 days of temps higher than 86 degrees. Oklahoma, Arkansas and the northern parts of the southeastern states like MS, AL and GA expect 90 to 120 days. Temps above 86 degrees average hardly a week in BC, and then they're not the searing 103 that we're expecting here today.

Another example of known heat effects is the recommendations of the American Rose Society. There are roses that are specifically recommended for the hot and humid south, for good reason. Some that thrive in very cold climates just curl up and die here.

Some plants simply cannot take our humidity. Others just appreciate the least bit of afternoon shade.

This explains why poppies bloom here in April and daffodils start in February, instead of everything blooming at once like in regular states. EOL (end of lecture)

Nell

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Comments (8)

PRO
Nell Jean
Original Author
14 years ago
I beg a thousand pardons from Bluesunflower, who lives in the PNW where it's cool and was not asking about sun effects. When I was typing, I was thinking about that lovely water feature and wondering why sun was a problem there.

It's OakleyOK who asked for this information. Sometimes I worry about me.

Nell
little_dani
14 years ago
It's o.k., Nell. I usually worry about me too. It doesn't help that DH has started telling me that I am 'not the sharpest knife in the drawer sometimes'. Grrrrr.

I still can't get over the fact that zone 8 goes way north in the PNW! I would just be thinking that it is cold, cold there, nothing like the truth!

Janie
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I'm in zone 5--or am I?
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i will make it as simple as i can .... and you will remember the simple explanation ... then gal will come and correct me.. and take it all to a higher level ... climate is 100 variables.. heat.. cold.. humidity ... and you can dream up the other 97 .... zone info.. in its simplest form.. is minimum winter cold ... and probably a bunch of other variables , but who cares ... lol ... so your 5.. is my 5... and st loius 5 ... for winter min ... but i have a conifer friend in st loius ... somewhere down there [kansas city???] .. who cant grow half the conifers i can up here due to summer heat and humidity ... go figure on that .... but we are both z5 .... so when we take the zone info to a nursery to pick out stock.. all we are doing is selecting plants that can live through winter .... as i said.. in its simplest form .... you can learn as much more about it as you want .... the effect of lake MI is two fold ... the amount of snow that covers your garden [lake effect] .. and the extension of the growing season due to that big mass of water you are near .... if you drew a line directly east... to MI .... i would not be surprised if they are z6 .... prevailing winds make fall a bit longer since it takes the water longer to cool .... and the ice in spring makes their weather a bit different than yours ... does the windy city wind blow to the lake.. or from the lake???? THEN.. we can fold in all the micro climate stuff.. like the effects of the cement jungle you live in/near, and how much heat it can retain .... etc .... but... i THINK your prevailing wind pattern is like mine.. from the NW .... so in theory ... you are on the wrong side of lake MI for it to affect you as if you were on the other side .... soooooooo ... if the zone maps tell you you are z5.. then yes you are .... but you MIGHT have a micro z6 ... but at that point you are going to complicate your gardening pleasure.. if you start zone pushing.. and buying plants that may or may not live over winter .... but that is another post .... micro's have a way of falling back to the lower zone every few years ..... ken
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Oh my. What is a passionate rose lover like you doing in that glacial hell hole? Reading about your endeavors has exhausted me and I haven't even lifted a shovel. I admire your grit and determination, but would love to see you rewarded with thousands of blooms on your rose bushes for all your hard work. I bet they could use engineers in zones 7 to 10!
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Hi Melissa -- did you ever get that email I sent you about digging a swale to capture rainwater on a hillside? I'm working on a similar project (slowly) and thought of you. Fundamentally I agree with you. It's best to grow plants that want to grow in the conditions you can offer them. I have a couple exceptions. You mentioned blueberries. I just adore blueberries. If you stick to the newer southern highbush varieties such as Misty, Oneal, and Sunshine Blue you may have better luck. Sunshine Blue in particular is said to be a little more tolerant of higher pH. Try a raised bed filled with compost, wood chip, and peat as a growing medium. I'm experimenting with the same mixture, some soil and sulfur added, dug as a trench in the ground. It is too soon to tell, but so far all but one of my blueberries are growing well and not chlorotic. I did lose one, but think that I lost it to hot dry weather when I was away. They do need water. I don't begrudge it to food plants. My other exception is that I planted a couple of avocado trees because Tom loves them so much. I'm not convinced that I'm going to be able to make them happy, but we're giving it a try. After killing about two dozen rhododendrons, I've given up on them. I have two left. One under the redwood trees actually looks reasonably happy. The other, alas, is on its way out. I do so love rhododendrons. At least I have roses! And apples. And plums, and figs, and citrus. Really, so much does well here that it is silly to sigh for the few plants that won't thrive for me. It means that when I go garden visiting and see favorite plants I cannot grow well, I have the special thrill that comes from seeing the less accustomed beauty. Rosefolly
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why can't I grow cosmos???
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I just barely cover the seed in the peat pods with soil/peat and keep them moist but not sopping wet. I have the little clear covered greenhouse thingys with a heat mat and lights over them. Cosmos take longer than zinnias to come up. Once they sprout, get them out of there quick so they dont stay too moist and damp off. From there, pot up in a 4in pot with potting mix with extra perlite mixed in. Keep under the lights or if its really warm out/no frost, then you can put it in a shady spot and acclimate to full sun before you transplant in into your garden. Once you have a lot of cosmos and zinnias established for some reason, if the ground is kept watered, they reseed themselves. It helps to mulch with straw or coastal hay etc. I think, initially, birds or squirrels might take some of the seeds but if there's alot of seeds then some make it. I have trouble starting sunflowers too in the garden..they sprout just fine but then something eats them! If I start them in a pot and wait until they are 5 or 6 inches high, then transplant them into the garden, they are fine. You can also try starting the cosmos & zinnias etc in 4 inch pots out in your garden. I started doing this few yrs ago. I put a whole bunch of pots together in a big clear tupperware/rubbermaid tub. There's holes in the bottom. I cover the top with chicken wire. You can water them with your hose sprayer without taking them out, this way. If its still a little cold out, like in very early spring, you can keep the lid on at night instead of the wire.
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natal
14 years ago
Nell, we can grow poppies down here? Which ones?
PRO
Nell Jean
Original Author
14 years ago
Annual poppies: Corn poppies, Breadseed poppies and California poppies, Natal. You might know corn poppies as Shirley poppies, and Breadseed poppies as Opium poppies.

California poppies are perennials, and can be cut back in late May to bloom another year. I pull mine up and leave any stray little plants that haven't bloomed. I still sprinkle seeds of all poppies in November for a new start.

Oh, almost forgot about Iceland poppies. They can be grown as winter annuals the way we use snaps and violas. They're kind of a sometimes thing for me, but I keep trying. They make a good substitute for tulips, if you can coax them into March and April bloom.

Nell

Here is a link that might be useful: Nell's Poppy Tales
natal
14 years ago
Well what do you know! Thanks for the link to your blog too! Now to figure out where to try 'em.
PRO
Nell Jean
Original Author
14 years ago
Natal, If you have a place where you usually grow zinnias, marigolds or periwinkles, you can pull the poppies and plant your summer annuals behind them.

Nell
bluesunflower
14 years ago
Nell ROFLOL! I read your post and I thought I was the one loosing it. I couldn't remember asking the question and thought "hoo boy it's starting." Glad to hear it was you instead. LOL

I did actually appreciate the info. These zone things can get fairly confusing especially when everyone is not using the same thing. Western Gardening has me in a 4, USDA has me in a 7. To complicate things further there are all these micro climates here. I suppose you all have them too? It's a wonder anyone knows what to plant at all.
natal
14 years ago
Nell, ok great! I have a patch of Zahara and Profusion zinnias outside my kitchen window. That might be the perfect place to try poppies. Thanks!

Heat Zones, or, Why Can't I Grow PNW Plants in the same Zone?

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Heat Zones, or, Why Can't I Grow PNW Plants in the same Zone?

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