We all know that palm trees grow in Florida but not in Missouri (duh). So, let’s say we start in Gainsville, FL and plant a mature palm tree every six feet, heading northwest toward Columbia, MO. Now, at some point the trees are going to have to be unable to thrive because of the cold climate, but here’s where it gets interesting: one tree, say #7,835,032, will not thrive, but the tree six feet to its southeast, #7,835,031, will.
Well, I don’t think that would be the case. I think that you would have a relatively large number of trees that are in between “thrive” and “dead.” Beyond the extremes, you would have trees that live okay but are a little rough around the edges, going gradually to trees which are barekly alive but do indeed make it through the winters every year, as we move from Florida.
Even then, not each tree will be as hardy as the next. So even if 30,031 is south of 30,032 it might just not be as healthy a plant and decline quicker. Although, from an ariel view, a line of palm trees going from healthy to dead over the course of miles and miles would be interesting.
“I guess it is possible for one person to make a difference, although most of the time they probably shouldn’t.”
[Random trivia]The farthest-north outdoor palm tree in the U. S. is in Williamsburg, VA. It’s kept alive by a hot air vent on the east side of the music building at the College of William & Mary.[/Random trivia]
In other words, the specific conditions matter a lot.
“Don’t take life too serious, son – it ain’t nohow permanent.”
Let’s assume (HUGE ASSUMPTION ALERT) that we hire a horticulture expert to see to it that the proper soil conditions are maintained for each tree, and let’s also assume that these trees are all cloned from a nearly perfect specimen of palm tree.
Now, all other things being equal, we are still left with the fact that at some point on the map (say, Buford County, Alabama) the trees are going to start to give out, albeit very slowly. So, tree #7,038,032 is 99.99% healthy, and tree #7,038,031 is 100% healthy. It’s those six feet that still make the difference!
Rasta, just because I feel like being difficult, there’s also insect problems to worry about, fungal problems, viral or bacterial infections, problems like root constriction, competition from surrounding plants for nutrients, chemical drift, physical damage from animals or machinery, differences in soil and air temp due to houses, asphalt, surrounding plants, and other factors and all sorts of other stuff.
It’s an interesting thing to think about, but not very practical. But yeah… I guess there are temp changes every six feet, all other things being equal.
“I guess it is possible for one person to make a difference, although most of the time they probably shouldn’t.”
As to the original post: It’s not that simple. Palms when affected by the cold have a range of appearances. From burned leaf edges, to entire exposed leaves dead (but the apical bud alive) to the dead bud. You could have that line of palms from Florida to Missouri, and you would see them all looking differently (I would bet some would be dead to the south of a few who would be barely alive, depending on what palm you plant).
Microclimates DO effect how well a tree is going to survive the cold. Palms are a good example. There are palms as far north as portland Oregon, i hear (they are windmill palms, Trachycarpus fortunei).
I believe the most cold hardy palm is the Needle palm (Rhapidophyllum hystrix, a native of south carolina forests IIRC). It can stand at it’s lowest, temps of -20 F.
Looking at a map of the USDA hardiness zones (which are not all nice and even, look here, a Needle palm could grow as far north as mid New York state, or in southern Michigan.
Anyway, it’s all about microclimates that will affect the outcome of a line of palms being alive in one spot and dead in another.
Oh and there is a needle palm in Washington DC at the National arboretum in the “Asian Valley” section of the garden, as well as one near the corner of 15th & P, NW, in Washington, DC.