world zones

i read that this plant or flower can be planted in zone 3 or 8 etc and my Q is how do i know my country or destrict zone///by the way i live in Jeddah, Saudi Arabia.

does any body has a link to a site that i can determin or learn about zones of plants? kindly send the link to my email spacehma@yahoo.com
regards

This message was edited Jan 28, 2008 9:09 PM

I'm not sure if there's a map out there to figure out zones in the rest of the world, but the zones are based strictly on the lowest winter temperatures that you could expect to have so as long as you know that, you can figure out what zone you're in. Here's a list of the lowest winter temperatures for a number of the zones, so if you know what your lowest possible winter temperature is you can look at this list and see where you fall. I didn't include some of the super cold zones because I'm pretty sure you're in a warmer area.

USDA Zone 4a: to -34.4 °C (-30 °F)
USDA Zone 4b: to -31.6 °C (-25 °F)
USDA Zone 5a: to -28.8 °C (-20 °F)
USDA Zone 5b: to -26.1 °C (-15 °F)
USDA Zone 6a: to -23.3 °C (-10 °F)
USDA Zone 6b: to -20.5 °C (-5 °F)
USDA Zone 7a: to -17.7 °C (0 °F)
USDA Zone 7b: to -14.9 °C (5 °F)
USDA Zone 8a: to -12.2 °C (10 °F)
USDA Zone 8b: to -9.4 °C (15 °F)
USDA Zone 9a: to -6.6 °C (20 °F)
USDA Zone 9b: to -3.8 °C (25 °F)
USDA Zone 10a: to -1.1 °C (30 °F)
USDA Zone 10b: to 1.7 °C (35 °F)
USDA Zone 11: above 4.5 °C (40 °F)

I just found this convenient paragraph on the internet, describing Saudi Arabia weather:

Summer is hot with temperatures in some areas reaching 49°C (120°F). Winter is cooler with an average temperature of 23°C (74°F) in Jeddah and 14°C (58°F) in Riyadh. Winter temperatures drop below freezing in the central and northern parts of the country and snow and ice sometimes occur in the higher elevations in the south-west.

It says right in the middle of that paragraph that in Jeddah, winter has an "average temperature" of 23 C. To me, then, that says zone 11! Probably higher, but our zone numbers don't go any higher! I don't know of anywhere in the US that has an "average winter temperature" of 23 C - sounds great!! But, I'm kind of happy that I never get 49 C in the summer either. I think I would melt! My dream-weather is about 18 to 27 C all the time.

So, I think the biggest concern about what you can grow in Jeddah is whether there is enough rain to sustain it, or if it is simply too hot for the plant to be able to grow well. I think it would be fine for a lot of tropical plants, but they may need more watering apart from any rain.

Claire

The zones are based on the lowest winter temperature, not the average. My average winter temp in the coldest months is 37F, which would put me somewhere between zone 10b and zone 11, and believe me, I'm definitely not! I also suspect that the average temperature they are mentioning is the average daytime temperature, rather than the average nighttime temperature which could be quite a bit colder. Since it's a dry climate, I'd expect the average nighttime temps to be at least 20F below the average daytime temps, and then the lowest temperature you could expect to see over the course of the winter would probably be about another 10-15F below the average. So I'd guess Jeddah probably is in zone 10a/10b, and Riyadh maybe 9b/10a.

I didn't consider them being daytime temps....oops! I did know that zones aren't based on averages, but I was saying that with an average of 23 C in the winter, it was doubtful that she'd go below 4.5 C at all. But, if night time temperatures are lower, then I've likely got it wrong. So, if night temps are 20 F below, and her average daytime winter temp is 74F, then her average winter nighttime temps would be around 54 F (roughly), and then taking 10 to 15 more off for lowest temps, and I'm coming out with 39-44.

Hopefully spacehma will be back to comment--I'm really guessing what the nighttime temperature drops would be (using what happens in my climate as a reference), but Saudia Arabia could well be different. Since their climate is probably drier than ours, it's very possible that the difference between day and night temps is even bigger than I guessed--we get a fair amount of rain during the winter which keeps avg day/night temps about 20F apart, but on sunny clear days, we can easily be in the 60's during the day and drop to the high 20's at night, so a consistently dry climate could have lower nighttime temps than what I was guessing. Regardless, I think it's safe to say it's on the warmer end of the zones!