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jon_beard89

The science of sunlight in different zones

Jon 6a SE MA
9 years ago

This graph shows how sunlight energy varies dependent on which latitude you are located.

The top curve is the power of sunlight at the equator or zero degrees latitude. The lowest curve is at the North Pole (or South Pole). The power (sunlight) hitting the Earth (all averages). As a location increases in latitude the energy decreases by a factor of 1 1/2.

23.5 degrees North is about the location of Mexico City. 45 degrees is just North of the US border.
My house in SE MA is at 41.9 degrees North

Montreal is 45 degrees

New York is 40 degrees

Atlanta is 33 degrees

Miami is 25 degrees

If someone took the time they could, by using the average sunlight power in the graph and the latitude calculate what effect latitude has on power from sunlight.

Then there would be elevation, desert areas, seacoast, lakes and a whole host of other variables that affect growing plants.

I just thought it was interesting to note that the progressive decrease in the angle of solar illumination on the earth with increasing latitude reduces the average solar irradiance by an additional one-half.

...or, you could just realize that a 'half day', 'full sun', 'morning sun' are spongeable factors dependent at least by your latitude and perhaps your attitude ;- ).

Jon

Comments (34)

  • DonnaDelaware
    9 years ago

    I realized now that I have the right latitude, attitude, and the spongeable factors for growing some really nice hosta.

    DD

  • paul_in_mn
    9 years ago

    "45 degrees is just North of the US border. "

    Jon, I'm at 45.0166820 latitude and at no time has my address been outside of the US......add another 11 states to MN that are at or above 45 including 3 in the eastern US.....just saying ;-).

    Altitude will affect sun energy as well.

    Paul

  • arthurm
    9 years ago

    Pretty complicated stuff. Add in the Gulf Stream and you get interesting weather. What is a Hosta? Lol.

  • Jon 6a SE MA
    Original Author
    9 years ago

    DD, that's the spirit!

    Paul, the link below is where I got the latitude info for Montreal which is listed as 45 degrees. Of course Montreal is South of much of the border. Sorry I made you a Canuck but I do think elevation covers mountains.

    Jon

    Here is a link that might be useful: Latitudes of various cities

    This post was edited by jonnyb023 on Tue, Jul 15, 14 at 21:56

  • jimr66
    9 years ago

    so jonny, what's wrong with Canucks?..... :)

  • Jon 6a SE MA
    Original Author
    9 years ago

    Jim,

    Did you know that Canada was originally just called CND? Every time people would ask 'CND'? How do you spell that? Canadians would answer C 'aye' N 'aye' D 'aye'.

    Just kidding Jim. Canada is a beautiful country and so are the people.

    Jon

  • Jon 6a SE MA
    Original Author
    9 years ago

    Arthurm,

    Probably a little hot in Sydney, but a quick look shows they do sell them there. The real question is how in the heck did you end up on the hosta forum?

    Jon

  • jimr66
    9 years ago

    Actually Jon, it's spelled C eh N eh D eh,. You've spelled it the Scottish way......lol

  • mountainy man z8 Ireland
    9 years ago

    I'm at 54 degrees and am in zone 8 here due to gulf stream, generally wet and windy climate. The angle of the sun is way different to people who live at a more southern latitude, I see many pics on here of hostas planted underneath trees where as we would need to plant behind or to the north side of them as the sun is lower in the sky and shines in beneath the canopy. I am planting trees at the moment to give me shade in a few years and have to take all this into account.

    Temps never get too bad/good? here the highest ever recorded was 33.C.(in 1887 lol!) had a couple of 30.C days last year and so far this year we've had a high of 24.3.C.

    Humidity is high here most of the time, we are a very soggy island and where I live is at the edge of a peat bog and that holds incredible amounts of water.(and midges!)

    So many different factors involved and so much to learn, the science is interesting.

    Not sure if I've gone off topic(we love to talk about the weather) but I'll leave you with something that you might find amusing, The definition of drought in Ireland according to our met office is 15 days with no recorded rainfall above 0.2mm. Doesn't happen too often lol.

    Denis

  • Linda's Garden z6 Utah
    9 years ago

    Intersting thread...I live just north of Salt Lake City in Utah. The latitude here is 41.7 which is pretty close to what Jon's latitude is but there is one big difference and that is altitude. Mine is about 4500 feet above sea level and I'm betting that his is nowhere near that high. The sun is very strong here in the summer with temps ranging from 90's to 100 degrees most of July and August and sometimes even in June. There is very little humidity here...it is very hot and dry. Your skin will burn in a short amount of time if you are not used to being in the sun and Utah has the highest rate of skin cancer in the US. That being said, I do have many hosta plants that get about 4 hours of morning sun from 8- noon and some that get a little bit of late afternoon sun and they are all doing fine. My Sum and Substance gets some afternoon sun and by August it doesn't look so good. Even my daylilys that are supposed to like full sun look melted by the time I get home from work. If I don't look at them in the morning, I don't get to see how pretty they are. I guess they would like some shade too.

    I believe altitude does make a big difference and I would hestitate to plant any hosta in full sun in any of the western states that are at a high elevation. Your best bet will always be early morning sun and shade during the hottest part of the day unless you live in the far north.

    Linda

  • Babka NorCal 9b
    9 years ago

    You are right. A 1/2 day sun for one person will NOT work for someone in another location. So much more to the whole equation. We don't get many cloudy days here so California Sun bites a lot harder than St. Louis sun at the same latitude.

    Jon- Haven't you heard of all the "kiwi" hostas? Check the library. Those are from New Zealand, right next door. We used to have a couple people posting from Australia. Theirs were just poking up when ours were going to sleep here.

    -Babka

  • hostacats
    9 years ago

    Jon I am from Canada and I had to chuckle at your little joke there.

    Jim good comeback eh?? LOL

    michelle

  • sandyslopes z5 n. UT
    9 years ago

    This is an interesting topic. tropic lover / Linda summed up my situation pretty well. (Yikes about the skin cancer statistic. I didn't know that).

    From what I'm learning some of my hostas that get crispy leaf edges might benefit from more water. But I have others that are in consistently moist sandy soil and they will get sun scorched on all the leaves facing the sun. I think we're about at 4800 ft. so the sun can be harsh.

    A side question.... Has anyone else checked out this web site, CityLatitudeLongitude.com? It gave me the correct latitude, but the maps are all cities in China. That's not just me that sees that, is it? I don't see a place to let them know about it, either. It's a little strange, that's all.

  • don_in_colorado
    9 years ago

    6,100' at my street address. Sun fries pretty darn hard here.

    Don B.

  • Babka NorCal 9b
    9 years ago

    Don. we were just recently out your way in Colorado Springs, Great Sands and Durango. Yes the sun IS more intense way up high.

    -Babka

  • Jon 6a SE MA
    Original Author
    9 years ago

    Jim, thanks for the correction, eh.

    Denis, I have been to 20 different countries and one of my regrets is never having been to Ireland it looks like a great place to live and full of friendly people.

    Michelle, I compulsively use that joke on Canadians whenever I can.

    Interesting comments on altitude. I wouldn't have thought it would increase exposure that much. Being higher does give longer exposure, but I wonder if (think) it has more to do with the thinner atmosphere at higher elevations.

    Anyway, great comments.

    Jon

  • arthurm
    9 years ago

    Sorry, just a quick visit via " most recent posts" didn't know it was the Hosta Forum.
    Seems a friendly place.

  • Jon 6a SE MA
    Original Author
    9 years ago

    Arthur, glad you stopped by and there are people here who can give you help in growing hosta successfully in challenging climates...so watch out!

    Jon

  • luckyladyslipper
    9 years ago

    Jon - thanks for starting a fascinating thread! For me, it was helpful to quantify (in a general, ballpark kind of way) stuff that was vaguely intuitive.

    Linda - my son, who fishes out in boats every chance he gets, never wears enough sunscreen. Thank goodness he does this in Massachusetts and not Utah!

  • Jon 6a SE MA
    Original Author
    9 years ago

    LL,

    Glad you are enjoying my hobby of collecting bits of sometimes useful: sometimes useless, but always
    interesting to me, trivia.

    Jon

  • dougald_gw
    9 years ago

    Jon

    Just a suggestion perhaps for those winter months when all is quiet ...

    We could use a more scientific or at least more rigourous study of the effects of sunlight, heat, water and length of growing season (or length of dormancy).

    From comments and pictures, it has become clear that light centred hostas dislike prolonged intense sunlight, most hostas dislike intense heat, sone sunlight is needed for good growth and so on. But we still are a bit in the dark on optimal strategies for various families of hostas.

    We have a large pool of growers who frequent the forum. Is it possible to collect data and attempt at least summary answers to the climatic questions?

    Doug

  • ken_adrian Adrian MI cold Z5
    9 years ago

    or, you could just realize that a 'half day', 'full sun', 'morning sun' are spongeable factors dependent at least by your latitude and perhaps your attitude ;- ).

    ==>>> or one could say ... shade is nearly undefinable in words ...

    there is a big sign on I75 .. halfway up MI ... that states you are halfway to the north pole ...

    man jon.. you have a thirst for knowledge ... two thumbs up ...

    ken

  • Jon 6a SE MA
    Original Author
    9 years ago

    Doug,

    Maybe pick a few of the most common hosta that the greatest number of people own and pick say a large blue, a large green, Variegated light center, variegated light rim, light green, light yellow and compare zones 4 through 7 along with set conditions such as morning sun, mid-day sun, afternoon sun, dappled shade, deep shade along with specific geographic conditions; coastal, lake nearby, altitude and of course 'attitude' which would include watering, mulch, fertilizer or not, potted, grounded.........I think its doable with a lot of co-operation.

    An averaging of results followed with a picture library and geographic location and conditions would complete the project and it would be a reference invaluable to those who want to know the best spots to plant hosta of various attributes, latitudes, geographic locales and attitudes and have the best chance to get the results they want.

    I would need a lot of help.

    Ken,

    Magnetic North or actual North?

    Jon

    This post was edited by jonnyb023 on Wed, Jul 16, 14 at 10:39

  • hostatakeover swMO
    9 years ago

    Denis, you gave us some of your high temps but I'm also curious what your lows are like (worst to average).

    Interesting thread!

  • dougald_gw
    9 years ago

    Jon ... I would be glad to help out - Doug

  • don_in_colorado
    9 years ago

    Indeed, Jon. Higher elevation, thinner air, less 'cushion' to protect from UV etc. = 'Whoa, I burned fast'!

    Exactly, Linda! High altitude = Hostas that get fried really easily in sun, even with plenty of water, zone be damned.

    Excellent thread, Jon, and very interesting. Thank you for starting it.

    Don B.

  • Jon 6a SE MA
    Original Author
    9 years ago

    Thanks Doug, I'm sure you will be a big help. I need some time to work up a checklist to quantify variables. I think using the most popular (by sales) over the last ten years and picking out the ones that best represent the variety we want would be the best way to approach it. People could refer to the 'checklist' and fill it in. Multiple choice "do you water' for example (y) or (no). I expect some might add anything we might forget.

    Shade is the prime objective, hours, full, dappled, morning, afternoon, full sun, full shade, midday sun, other....but watering, rainfall; other recent unusual weather...and of course, we need pictures to judge and measurements age....

    I'll give it some thought and work up a draft and post it here for you and anyone else to critique. With a little work we can become pretty expert on the proper siting of hosta.

    Thanks Don, I think we can have some fun with this.

    Jon

  • mountainy man z8 Ireland
    9 years ago

    Hosta Takeover, the lowest air temperature ever recorded was -19.1C. in Jan 1881 at the Markree Castle observatory which is close to me here, in more recent times lol we had a couple of severe winters recently and I recorded a -17 here in 2010. average winter temps would be in the 4 to 8 C range mostly with most areas getting 40 frosts over the winter.

    Winter here is generally mild wet and windy the Atlantic keeps us cosyish. This past winter was very mild and stormy but I still had 7 snow days, I live quite high up in the mountains and am usually guaranteed some snow at some stage.

    Thankfully extremes are rare here but I keep the freezer full in case I can't get out, 4x4 essential (and fun!).

    Denis

  • Linda's Garden z6 Utah
    9 years ago

    Don, I water my hostas every day in the heat of the summer and still Sum and Substance and Parhelion are looking a little ragged now. Paul's Glory gets bleached out and has just a touch of burned edges on a couple of leaves. I did plant an Atlantis in a spot that I think gets more sun than any of the others do and so far it looks fine. I will continue to monitor this plant and see how it does.

    The worst sunburn I ever had was in the winter skiing at Snowbasin. My face was so fried I could not smile for weeks, it hurt so bad!

    Linda ;-)

  • User
    9 years ago

    For every degree of latitude, if you consult the nautical charts, you notice that each degree is comprised of 60 minutes, and those minutes are one nautical mile which is 6,000 feet. A statute mile (not kilometers, haven't looked at that figure) is 5,280 feet....so do the math..

    So if I lived exactly on latitude 30 North, and wanted to go to latitude 45 North, straight up the latitude line, it would be 15 x 60 = 900 NAUTICAL miles. Too tired to do the math, but you see how things can change significantly with the only variable being the LATITUDE.

    When you get into elevation, that gives a whole different perspective on it.

    However, I found the world cities by latitude and discovered that when they mentioned Mobile AL, which is where I am, there were multiple Chinese cities or areas which shared the same location above the equator. I wish they had added the altitudes too. What I was checking at the time I consulted that website, was which of those areas were originally native habitat for plantaginea, my most favorite hosta the fragrant ones.

    Incidentally, Madelon Gillegan is in Australia, and she is a hosta hybridizer. She participates in the AHS auctions as well, with seeds of her hosta offered, and with jewelry made in Australia too. Just thought I'd point that out, while parts of AU may not be pleasant for hosta, other areas are.

    Always pleased to have folks from Australia join us, ArthurM.
    Welcome.

  • Jon 6a SE MA
    Original Author
    9 years ago

    I didn't have much luck in finding data on the sales of various hosta, so Plan B. Please review the following list of Hosta of the Year and give your opinion on which best represents the following.

    1- Best example of dark blue or green

    2- Best example of light green or Chartruese for the French literati among us.

    3- yellow

    4- Light outside margin / light center (Fragrant Bouquet, for example)

    5- Light center variegated

    6- Light rim variegated

    7- Tri-color

    8, 9, 10 ?????????

    Thanks. This is where I will need help in the project. I will tally the votes and then submit a questionnaire for the people's choices of representative hosta to evaluate the conditions grown and evaluate the results in a variety of locations and conditions to provide a guide to the age old question 'How much sun should I plant this hosta in?'

    2014 'Abiqua Drinking Gourd'

    2013'Rainforest Sunrise'

    2012'Liberty'

    2011'Praying Hands'

    2010'First Frost'

    2009'Earth Angel'

    2008'Blue Mouse Ears'

    2007'Paradigm'

    2006'Stained Glass'

    2005'Striptease'

    2004'Sum and Substance'

    2003'Regal Splendor'

    2002'Guacamole'

    2001'June'

    2000'Sagae'

    1999'Paul's Glory'

    1998'Fragrant Bouquet'

    1997'Patriot'

    1996'So Sweet'

    If you think there is a hosta that would be widely grown and fits a particular niche, then please add it to the list. The object is to get as many examples as possible in order to get the best sampling, it is not a vote on which one you like best.

    Thanks,

    Jon

  • Jon 6a SE MA
    Original Author
    9 years ago

    ?????
    Jon

  • dougald_gw
    9 years ago

    Jon

    I grow only a few of the hostas on the list so will offer some examples that I do grow ...

    1- Best example of dark blue or green - Hadspun Blue, Blue Angel or Elegans

    2- Best example of light green or Chartruese for the French literati among us.

    3- yellow - Sun Power, Key West

    4- Light outside margin / light center (Fragrant Bouquet, for example)

    5- Light center variegated - GE, Dream Weaver, Orange Marmalade, June

    6- Light rim variegated - Liberty, Fortunei Aureomarginata

    7 Tri-Colour

    Another possibility is to consider plants with certain genes in them ...

    In any case I have given an idea of hostas that I grow that match your list. I do have many others depending on what is eventually chosen as representative.

    Doug

  • Babka NorCal 9b
    9 years ago

    Too many variables. Say 3 hrs of sun facing South between 1-3 pm????for instance, with totally clear sky?

    Good luck.

    -Babka

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