Peaseblossom: thats a very good question and discussion. I also have asked to myself most of the times, about that factor, but while this forum is usually visited mostly by USA citizens, so, at least in here is not usually a problem.

In my situation it is not the amount of heat and sun needs to grow/bloom/fruit but how much can they endure them. Here in northwest Mexico, near to the desert, it´s just too hot and the humidity is so low that even when I am just 100 km north of the tropic of cancer(23°N) I can´t grow most of the tropicals nor the fruit from temperate weather! It´s so frustrating. I am in a semi-desertic area. So it is obvious I can´t grow a cherimoya but also not a soursop (it´s better than cherimoya, lol)! And sometimes the country gets a mild freezing, I hate my climate. Right now day temps. are about 105°F and in about 2.5 months night lows will be around 52°F, so the ultratropicals will suffer both in summer because the lack of high humidity and in winter because of low temps (something like south cali valleys, but they can grow cherimoyas!) >=: I am relief now. At least I can grow suggar apples without any problems. Hope atemoyas do well in here.

Just a few moments ago was watching grown ups pedalai and marangs in the Fairchild exotic pavillion, and I felt so down because if they need a greenhouse to grow these in there, what are my chances to grow those in here! lol I have zone denial, trying to grow mangosteen, durian, marang, pedalai, etc. But at least I know I am not alone (Marcelo and his pingan almost in north pole, lol).

Peaseblossom,

California rare fruit growers describes preferred climatological conditions for various fruits. Cool winter temperatures (rarely below freezing in many cases, but temperatures below 50 are common) are the primary limiting factor for tropicals in California.

Ryan

Peaseblossom, usually I find minimum temperature listed is usually just how low a temp the plant can take before getting damage. For myself, the amount of heat is definitely more important, for most of my tropical I don't get any frosty nights that will damage them. But I run into weeks and weeks of cool wet weather that is just as bad or worse, many can die from root problems because of this, especially younger trees. For others in a different climate the minimum or maximum may effect them more. Its effected by much more than min temps of course, you have to think about heat, water, humidity, sunlight, etc.

It seems like you got a lot of question within that question. Just an amateur thoughts, but from what I understand Plants require different conditions to grow, bloom, and fruit. Just because a plant grows in one condition doesn't necessary means it will bloom in that same condition.

This will be my small input on the blooming aspect. Blooming seems to be affected by changes in temperature, water, and sunlight or any combination of them. In theory, if a plant gets an environment where it actually remains PERFECTLY consistently year round, it may rarely or never bloom.

For example longans require a part of season where its cool and dry to bloom. Southern California for example seems to get cool enough in winter for them to bloom even though it rains, but a place like Thailand, weather must actually be cool and dry. They probably just don't get cold enough, so it requires a combination of lower temps and dry weather.

Mangosteens on the other hand probably doesn't require any kind of temp change, its considered much more sensitive to damage from temp change, something like that would kill it. Therefore they are only grown in the most tropical area. Therefore blooming for mangosteens is known to be much more affected by the wet and dry season.

Just my two cents.

Well I have noticed that the UV level seems to be a factor in growing temperate things like tomatoes here.

Some plants that might be full sun in a more northerly climate, just won't survive a summer sun in this latitude for very long. And it's not a matter of temperature or humidity, but definitely of the sun strength. (My skin isn't the only thing that crisps up under excessive tropical sun. *lol*)

And speaking of zone denial Patusho, I've just put in some delphinium seed to see if I can take advantage of the cooler weather here.

Thanks for the great input guys, it definitely supports what I've been thinking. I guess the only way to really find out what will grow in your climate is to try it, right?

Most (if not all) plants (including tropicals) stop their growth at 100*F. As for the climate zone, yes, you're right. South Florida zone 10B is so much closer to the true tropical climate than same zone in SoCal. Just compare Miami and San Diego, or West Palm Beach and Los Angeles. South West England is zone 9 but is SO much cooler than Orlando,zone 9 (B?). And so on...

No offense intended at you Peaseblossoms, however, having family members living in Southeast Asia I would like to add my 2 cents on the climate of Tropical Asia.

-Lychees (as well as a variety of citrus) are native to the regions of Southern China and North Vietnam. Here winter temperatures can get quite cool, but rarely, if ever, freezes. Just what the tropical/subtropical lychees need in order to flourish and reproduce. And is the main reason why lychees can't be grown in low lying areas of South Vietnam where winter lows get down to only the upper 60s-70s Fahrenheit and daytime temperatures are in the upper 80s-90s Fahrenheit. Longans, a more tropical relative, are the crop of choice here instead.

-Mango trees are native to the Southeast Asian region of Eastern India and Western Burma. The lattitude here is slightly tropical to subtropical (25-22.5 degrees). In its native habitat mango trees do not need to worry much about freezing temperatures and they are virtually actively growing year round, with one of the biggest factor affecting growth being water availability.
So you ask how can they grow up there when temperatures there rarely gets above the high 70s in winter time? Not necessarily. High temperatures in Mainland Asia are determined to a large extent whether the area is located above or below the Himalayan chain. As you may have already know, the higher the mountain chain the better it is able to protect the lower valley from destructive Northers. The Himalayan chain is highest north of India where the tallest mountain, Mount Everest, is located and gradually descend as it reaches further east. Look at the map of Asia daily winter forecast and you will see that areas south of the mountains have dramatically higher temperatures than just north of the mountains. How dramatic you say? The Northwestern Vietnamese city of Lao Cai daytime temperatures can be 15 degrees higher than the capital Hanoi further east EVEN THOUGH Lao Cai is at a higher lattitude than it. So when Hanoi is forecasted to reach 75F for high, Lao Cai can easily reach 90-92F!! It's all your location relative to the mountain. There are existent mango groves in North Vietnam, just not as many as those further South. Theoretically speaking it is possible for a mango tree to live 500 years in North Vietnam with dormancy level decreasing the further west you go, generally speaking. I think this is enough for now. Boy I felt like i'm teaching a weather class lol.

GardensAlive,

You provide a good reason for the need for an Asian gardening forum.

Though once you move away from the shelter of the Himalayas, latitude is the key to the effects of the Northeast Monsoon, which kicked in about 2 weeks ago. (and there are microclimates from ocean and local mountains, but just speaking in general)

Thankfully Hanoi and Hong Kong never end up getting as cold as Beijing or Seoul or Sapporo or you wouldn't be able to grow the lychee or longan here effectively.

Pease--in peninsular Florida, light intensity is perhaps the toughest factor is selecting a plant's location in the garden. Here, all is fine until the summer, when the intense sun is teamed with the high humidity (particularly at night), and all of a sudden, plants fade.

But, there are many things that contribute--the characteristics of your soil for example, can offset light exposure in some plant species, too.

Thanks for the input all...and GardeAlive, no offense taken, although I was just stating my observations from having lived most of my life in Hanoi, Saigon and Bangkok. I tend to see a lot more "tropicals" in Bangkok, Saigon, etc than in Hanoi. In any case, my question was not really about those plants, but about whether some plants' growth is influenced by more than just minimum temps (obviously it is, so I wanted to start a discussion about it). This was sparked by my observation that people generally make assumptions about zones that aren't necessarily true. After all, a place that remains 50F and cloudy year-round is still "zone 11" but I wouldn't call such a place "hot"; would you? I doubt you could grow the same things there as you could in sunny California.

And Daai_Tou_Laam--yes we need that forum!!

I feel like I'm in a weather class and geography course! lol. Just kidding.

Great to see you back GardenAlive. I was wondering how Galveston took those hurricanes. How did your yard hold up? Crazy weather in the last year.

Eggo - There's a reason that the Farmer's Almanac is one of the leading weather trend sources.

And I went out to the Kadoorie Farms and Botanical Gardens yesterday and forgot my hat. If this were summer, I'd be regretting that tremendously as I'd be burned to a singe.

Even though it is still unseasonably warm here, the UV intensity is about half of what it is during the summer. I think this is critical as summer is wet season and now is dry season. I don't think the local vegetation could survive a dry season that is combined with the summer UV levels. The grasses are rapidly drying out, but the established trees are okay.

Tom, thanks for the notes on the UV intensity. One of the many factors I've never thought about before.
But seriously a tradeoff between tomatoes to mangos, jackfruits, sugar apples, lychees, longans is not really a tradeoff in my book. That's an upgrade. lol.

Peaseblossom,
I just want to provide a little information that I thought might be interesting since you're talking about the climate there...and thanks for the reiteration! How long have you lived in Vietnam?

Dai,

Since Hong Kong is located in the tropic, shouldn't light intensity be the same throughout the year since the sun is always directly overhead in the tropic? Just curious since I never lived that far north in Asia. Thanks

Eggo,
Thank you so much for asking that question. You truly have a heart of gold! Yes, it was a horrible experience. One that I will remember for a long time. We had our fair share of tropical storms and hurricanes but usually stay home.

Not this time though. People in the Galveston/Houston areas were freaking out over what had just happened in New Orlean caused by Hurricane Katrina. This was actually the first time I saw people in this region of Texas got serious and worried about this other hurricane, Rita. All I can say was it was horrible. Not in the sense of the storm, but the traffic!! Yeah, we decided to evacuate the island--first time ever since we moved here. We were fortunate, I take that back, very fortunate for leaving a tad bit earlier than the mass exodus of cars and trucks that followed us shortly afterward toward Houston. We stayed at a close family place up there and decided that we're going to weather out the storm if it decides to hit here head on. On our way to Houston we listened to the radio and the weather forecaster told us that Rita was to become a category 5 hurricane!! It eventually became the third strongest hurricane on record in the Atlantic and it was heading toward Galveston!! My family was ready for the inevitable. What if we no longer have a house? What if our business is gone, what are we to do? Family prayed all night and the next day and the day after. With every day gone by, the hurricane got weaker and weaker. When it almost landed, what was once a 175 mph freak of nature in the middle of the Gulf mellow out, miraculously, into a 125 mph wind of destruction. Yes it was still a killer hurricane but a much less destructive one nontheless. And I be darn, the thing all of a sudden decided to head slightly due east from the projected path!! We felt very relieved for us and our friends back home on the island even though East Texas and Louisiana will feel the brunt of the hurricane. I wished it didn't hit anywhere in the U.S. but a direct hit on Houston, the fourth largest city in the U.S., will most likely have caused catastrophic damage to the city much like New Orlean, possibly more even.

Long story short, Rita decided to hit almost dead center at the Texas-Louisiana border and caused extensive damages from Port Arthur, Tx to almost the entire left half of Louisiana. Fallen trees, flooding, mass electrical failure, toppled houses, looting, you name it. Everything that could easily have happened here had Rita wanted to. Fortunately, Rita didn't stay too long to cause more damage once it made landfall.

The whole event was chaotic for the millions of Texans as well as Louisianans who had to endure it. Houston, a city that once housed the largest shelter for Katrina refugees, the Astrodome, eventually looked destined to become another New Orlean. One can only imagine what was on the minds of Katrina refugees who was forced to leave their beloved city just weeks ago. Soon they were forced to go on buses heading toward other refugee camps in Arkansas, San Antonio, and Dallas to name a few. And locals, can't forget them. Took us about 6 hours to drive 50 miles and I thought that was insane. Later I heard some people had to spend a whole day just to leave Houston!! At the peak of traffic chaos, going from Hwy 160 east to Hwy 160 west withing the city was a 6 hour journey!! Cars were idling too long, many without gas, many pleading to the government for food and essentials. It was just horrible. The worst traffic jam you can possibly think of in Texas.

Back home we felt very relieved that our house and business were intact. Rita was not so forgiving to our garden though. We had many toppled trees such as our large moringa as well as a couple of large indian jujubes. The two year old royal paulownia tree was bent, and still is. I'm trying to fix that somehow. And our papaya grove is left in ruined. Lots of torned leaves and broken papaya trees bent in half. Overall, half of the papaya trees are gone but those left were quickly re-erected as were all the other trees that fell. Fortunately, non hit our house and caused any major damage.

Boy what a crazy year it has been. A record hurricane seasons, hurricanes of which the most massive ever recorded. And the freak snow, who can forget that. I'm just amazed at how all these so call tender mango, papaya, avocado, pomegranate, moringa, rose apple, indian jujube are able to withstand these conditions. I guess, like a migrant from the tropic, if I can do it so can they!!

GA - Hong Kong is located just inside the Tropic of Cancer at about the same latitude as Honolulu and Hanoi. So that means the sun is directly overhead only at the summer solstice. Due to the Earth tilting the sun is now South of the Equator and by Dec. 21 is overhead at the Tropic of Capricorn, resulting in the shortest day of the year in the northern hemisphere.

And for your random trivia of the day, according to the Chinese Lunar Calendar yesterday was the first day of winter. I checked last night around 8:30pm and it was 25C (77F)and 90% humidity.

I only seen what was showed on the news, the insane traffic out of there but not really of the aftermath of the hurricanes though. I'm very happy to hear your home and business are still intact. You can always replant the trees. =)
I had completely forgotten about the ice storm you Texans had over there too.

Tom, 77F and 90%, that's winter?!?!? hehe I gotta visit HK one day.