Full-Sun Agaves?

[agavegreg]

I should think A. attenuata would burn up in a Phoenix summer minute in full sun. They grow A. desmettiana in full sun though. ugh!

[lorax]

Hmmm. I doesn't at 10,000 feet in considerably stronger, drier sun. Maybe it's a moisture thing.

[Boo Hollow]

One factor that can be helpful is understanding that the amount of sunlight reaching an area is a complex 3D function that is not going to be the same for every "low desert" area nor equivelant latitude and longitude. Altitude and other factors also play into it as well as what the ground surface is albedo effective(reflective lighting = heat gain) convection currents - winds and couple that with available soil moisture, etc to attempt to determine suitability for plants in a given environment. For those interested in really trying to calculate the amount of solar influence (surface irradiance or diffuse irradiance) please see the following link:

www.spot3d.com/vray/.../render_params_advancedimap.htm

We do this on a daily basis for all of our solar farm installation designs. Very useful in understanding the slight differences within a region.

[agavegreg]

I don't know your climate. Can you fill me in? Average high in mid-summer in Phoenix is 105 F, frequently with overnight lows over 90 F, 3 inches of summer rain, and humidity? what's that?

Originally Posted by lorax

Hmmm. I doesn't at 10,000 feet in considerably stronger, drier sun. Maybe it's a moisture thing.

[Allen Repashy]

As Greg points out, I think it is more heat and humidity, than actual sun exposure that does the damage. There is significantly more UV produced in full sun at high altitude but rarely do you get week after week of high temperatures over 110 degrees as you do in Phoenix..

Your skin can get used to full sun, and if you have a good tan, you can sit in it all day long on a warm sunny day...... but try sitting in the sun all day when it is 110 degrees out..... or for that matter, try sitting in the shade all day at 110F .. it sucks

[lorax]

My climate is what's classified by the excellent Koppen-Geiger Climate Systematics as BSh - hot altitude desert. I'm located on a mixed sandstone/limestone bed in an interandean valley, in the rain-shadow of two stratovolcanoes - active Tungurahua and dormant Chimborazo. Geographically, I'm at just a bit under 1 degree of latitude South and roughly 78 West. My home is located at just a hair under 10,000 feet of altitude above sea level.

Dry season average daytime high is 45-50 C (113-122 F) with overnight lows in the upper 20's (80-85 F). Average rainfall is ridiculously low (2-3" a year if we're really lucky), and humidity is somewhere around 25% most of the time.

Wet season average daytime high is anywhere from 15-40 C (60-104 F) depending on cloud cover - obviously, with more cloud, it gets colder, since there isn't a whole lot of atmosphere at this altitude to trap heat. Overnight lows in the wet season range from 5-15 C (41-60 F). Even in the "wet" season our humidity only goes up to about 50% unless it's actively raining (which is infrequent - we mostly get moisture from mist out of ground-level cloud instead.)

The balance is roughly 8-10 months of dry season to 2-4 months of wet season, although this year the wet season has dragged on for nearly half a year, and everybody's freaking out because it seriously sets back the corn and quinoa crops and has greatly increased the incidence of fungal plant diseases.

I grow a number of Agaves, cacti (particularly Opuntia, Austrocylindopuntia, and Cylindropuntia, but also Echinocactus and Echinopsis, and one sad Hylocereus undatus that I need to mist more often), a wide range of desert bromeliads, and other native paramo plants, as well as the tougher Aroids. I also grow a full food garden in a more shaded area of my backyard. My soils are alkaline (pH 7.8 to 8.3) and sandy; I have had to amend heavily for my food crops.

[GermanStar]

No doubt it's more complex than simple sun exposure, after all, we're talking about "burn" here, and burn results from heat. Walk on a shady patio in Phoenix mid-day, mid-July in your bare feet. Now try a sunny patio. Believe me, if Phoenix just had trees to provide a little shade, it would be a far more comfortable place in the summer. Take a moderately sun-sensitive Agave like a blue glow, and place in a nice spot with some filtered light here, and it's happy as a clam. Place it in full 12-hour sun, and you may as well call it a yellow glow.

[wantonamara]

Altitude changes atmospheric pressure, (That's an understated given). I wonder how this pressure alters the capabilities of the plants to withstand the heat itself? is the plant able to shed heat quicker at 10K ' versus Phoenix. I wonder about the mechanics of the peramo versus the low altitude hot desert. They both seem equally both hot except for the 10 degree difference at night. It is at times like this that I rue that I am such a hopeeless layman.

I am just amazed anyone is growing any crop at those average daily temperatures. Things shut down and go dormant and crinkly when it gets that hot here.

[GermanStar]

Ecuador Weather Forecast - Average weather conditions for RUMIPAMBA, Ecuador - Freemeteo.com

Us-arizona Weather Forecast - Average weather conditions for PHOENIX/SKY HARBOR, INT, AZ., Us-arizona - Freemeteo.com

[wantonamara]

I looked at the map on the weatherstation and It does looks like the weather station is in another climate than Ambato, both in elevation and in vegetative cover, and outside the rain shadow.. it is probably not very descriptive of what Lorax is describing..

[lorax]

Ambato, to my eternal shame, doesn't have a weather station with any major service. Its weather is normally reported internationally from the military airbase in Latacunga, some 50 km distant and in a completely different biome and elevation. Latacunga is cold, wet paramo.

I'm surprised you found the Rumipamba station - that's on the slopes of Chimborazo, another 1,000 feet or so above me, in cold wet paramo. The weather it reports is much closer to that of the town of Salinas de Bolivar than it is to that of Ambato.

[GermanStar]

Rumipamba is 26 km away, elevation is about 9100 ft. BTW, the highest recorded temperature in all of S. America is 120° F. Listen, I'm sure it's hot there, if you say it is. I just think you're overstating it by a bit. C'mon, 10,000 ft., 122° and 45% humidity? I'm pretty sure that's Venus.

Phoenix is in the general area of the second highest recorded temperature on Earth, and when we hit 45% humidity, which is rare, we struggle to make it to 100°. We make it into the mid to high hundred and teens quite a bit, but the accompanying humidity is generally less than 10%.

[lorax]

Different Rumipamba then - that will be the one on the way to Riobamba; again, it's a different biome. BTW, that placename is the equivalent of "Springfield" in the US....

C'mon down and visit! Summer (Dry season) is in December, usually. The temps I'm referencing are my own records from my backyard weather station and historic records that I had to go dig out of the Ambato archives - those went back about 200 years, although I'd only regard the measurements since about 1950 as being accurate. This area is very similar to the Atacama desert (another place I've lived, although I wouldn't care to repeat the experience....) We rarely, if ever get the combo of 122 and 45% humidity - that's a coastal or deep Amazon phenomenon on dry days. If it's that humid here, we're inside a cloud, which is naturally blocking off our sun and so it's quite a bit cooler.

[GermanStar]

Originally Posted by agavegreg

We are still talking full sun in the low elevation desert southwest, Phoenix, Palm Desert and the like. In mid-elevation areas (>2000 feet) like Tucson, and higher humidity areas like central Texas, the list will grow some. Maybe we can tackle those areas next.

We need to add Agave colorata, A. geminiflora, A. multifilifera, A. pelona, A. schidigera and A. subsimplex.

I brought our up-to-date list to the local nursery today for additional input, and the fellow who runs the place would cross two off the list, A. geminiflora, and A. Sharkskin, he has had both react poorly to mid-day sun exposure. Of course, this is at his nursery, so we're talking potted plants, perhaps the difference.

[GermanStar]

...............

[GermanStar]

Hope he's wrong about the Sharkskin. I moved my A. bovicornuta , and placed a new 5-gallon Sharkskin in its spot this morning. Maybe I should protect it with a lawn chair mid-day for a little bit while it adjusts to its new surroundings.

[agavegreg]

He says no to A. geminiflora!!! It's all over Phoenix in full sun and doing great!

'Sharkskin' has some A. asperrima (= A. scabra) in it that should help its sun tolerance. You might have to protect it until it gets established though. Don't want to recommend throwing anything out into Phoenix full sun this time of year without acclimating it.

Originally Posted by GermanStar

I brought our up-to-date list to the local nursery today for additional input, and the fellow who runs the place would cross two off the list, A. geminiflora, and A. Sharkskin, he has had both react poorly to mid-day sun exposure. Of course, this is at his nursery, so we're talking potted plants, perhaps the difference.

[agavegreg]

Sorry I asked, man I haven't thought about the Koppen classification for 25 years! Where have the years gone?

Seriously, 113-122 daytime highs? Is your thermometer in full sun? I have absolutely no concept of the climate at 10,000 feet so near the equator, so please forgive my ignorance.

Originally Posted by lorax

My climate is what's classified by the excellent Koppen-Geiger Climate Systematics as BSh - hot altitude desert. I'm located on a mixed sandstone/limestone bed in an interandean valley, in the rain-shadow of two stratovolcanoes - active Tungurahua and dormant Chimborazo. Geographically, I'm at just a bit under 1 degree of latitude South and roughly 78 West. My home is located at just a hair under 10,000 feet of altitude above sea level.

Dry season average daytime high is 45-50 C (113-122 F) with overnight lows in the upper 20's (80-85 F). Average rainfall is ridiculously low (2-3" a year if we're really lucky), and humidity is somewhere around 25% most of the time.

Wet season average daytime high is anywhere from 15-40 C (60-104 F) depending on cloud cover - obviously, with more cloud, it gets colder, since there isn't a whole lot of atmosphere at this altitude to trap heat. Overnight lows in the wet season range from 5-15 C (41-60 F). Even in the "wet" season our humidity only goes up to about 50% unless it's actively raining (which is infrequent - we mostly get moisture from mist out of ground-level cloud instead.)

The balance is roughly 8-10 months of dry season to 2-4 months of wet season, although this year the wet season has dragged on for nearly half a year, and everybody's freaking out because it seriously sets back the corn and quinoa crops and has greatly increased the incidence of fungal plant diseases.

I grow a number of Agaves, cacti (particularly Opuntia, Austrocylindopuntia, and Cylindropuntia, but also Echinocactus and Echinopsis, and one sad Hylocereus undatus that I need to mist more often), a wide range of desert bromeliads, and other native paramo plants, as well as the tougher Aroids. I also grow a full food garden in a more shaded area of my backyard. My soils are alkaline (pH 7.8 to 8.3) and sandy; I have had to amend heavily for my food crops.

[GermanStar]

Originally Posted by agavegreg

He says no to A. geminiflora!!! It's all over Phoenix in full sun and doing great!

'Sharkskin' has some A. asperrima (= A. scabra) in it that should help its sun tolerance. You might have to protect it until it gets established though. Don't want to recommend throwing anything out into Phoenix full sun this time of year without acclimating it.

Sound advice, better safe than sorry. I'll try a 10 - 3 lawn chair over it for a couple of weeks or so. It will still get lots of sun but have full protection from the worst of it. If some clouds return any time soon, it shouldn't be much of an issue...

[Matt Maggio]

Remember, Agaves are CAM plants. Nighttime temps much above 20 degrees C (68F) will severely inhibit stomata opening, gas exchange, and thus productivity. Even species adapted to warmer lowlands can exhibit reduced growth.

I have a middle-aged ovatifolia in the ground that shows yellowing and wrinkling above 100F.

I have burnt numerous immature agaves across the spectrum, Agave pelona and utahensis can be very susceptible when young. Think about where they start off... white to gray-colored limestone rubble (cooler surface temps), in cracks and crevices and/or under nurse plants.

[lorax]

Originally Posted by agavegreg

Sorry I asked, man I haven't thought about the Koppen classification for 25 years! Where have the years gone?

Seriously, 113-122 daytime highs? Is your thermometer in full sun? I have absolutely no concept of the climate at 10,000 feet so near the equator, so please forgive my ignorance.

You should check Koppen again - it's been updated. The difference between the current and the 25-years-ago maps is pretty neat.

My thermometer is in part shade, actually - and a high like 122 isn't sustained; it's a spot temperature. 113-115 is more normal. The thing that makes Ambato's climate so unique is partially the altitude, and partially the location vis a vis the two volcanoes.

Altitude first. At 10,000' the atmosphere is considerably thinner than you're accustomed to - in most of the rest of the world, it's somewhere planes fly, not somewhere people live. This has a few meanings for our temperatures - first, when it's sunny, it heats up really quickly because there's less atmosphere between us and the sun. Second, the UV index here is off the charts (despite the ozone layer being thickest around the equator.) Third, we don't hold heat, for the same reason that we heat up quickly. A long bank of high cloud that passes in front of the sun can actually drop our temperatures between 10 and 15 degrees C (50-59 F) in the matter of about a minute.

Location second. In the rain shadow of both Ecuador's tallest mountain and one of its most active volcanoes, it's pretty freakin' dry. I'm not sure if you realize this, but an active volcano generates cloud by virtue of being hotter than anything else around it, and the net effect for Ambato is that it's far less humid here during an eruptive period than it is during a calm one because the volcano is literally sucking all the water out of the air. I also get about 1/64" or less of fine volcanic ash each day falling into my garden - just enough to be a really excellent fertilizer. It does mean that I have to wash my plants on cloudy days, though, because ash buildup can choke them. The sandstone/limestone base that the city is on also contributes to its dryness, since water doesn't stick around on the surface. Despite all of these challenges, Ambato is the country's fruit basket, and has some of the richest (albeit slightly alkaline) soils found in Ecuador. If you can irrigate, you can grow almost anything here. Where I live used to be part of the Inca royal gardens.

Hope that helps - it's a very unique situation to live in.

[Pat McNeal]

I was in Death Valley September 1st in the late 70"s and the ranger said they recorded a 128 reading, my gum sole tennis shoes melted to the asphalt like walking with you shoe bottoms covered with gum. The poor ranger had just been transferred from Isle Royal in lake Michigan to Death Valley he was not ready for the heat.

The Sacramento valley where I grew up would get up in to the low teens some summers 112-113. But 102-103 in Texas is worse.

I got off a plane at Skyharbor on cheap SW flight had get off the plane and walk across the tarmac. in town it was 117 out on the tarmac 130 -140.

On the local news they had a story about kids starting fall sports and band etc. the reporter had a infrared heat gun and got a temperature of 141 at field level.

I bet in Abamto nothing rots, not many bugs and a there is fair amount of dust. How do you keep your computer running? My brother lives in Alaska and every time they get ash fall, it gets into the electronics and short them out.
My sister in law works at a hospital and they spent millions on filters and air treatment to keep the fine dust out of all the machinery.

[lorax]

I live in an adobe house and don't open my windows much. The ash doesn't get into the house too badly except at the doors (the kitchen door, for example, is almost always open because the shade from the backyard cools the air), and vigilant sweeping keeps it pretty much under control. You should also bear in mind that I live in an area of very limited ashfall - my friends downhill in Baños, at the foot of the volcano, have all but given up on computers until the eruption stops. The volumes of ash seen in Alaska due to the Mt. Redoubt eruption have been on the order of 100s of times larger than what I get.

Oh, and I get earthquakes, too. We had one this morning, which I'm shocked to find was a 6.9 epicentered in the jungle about 125 km away from me - it didn't feel anything like that strong - no structural damage or anything. The last time I was in a 6.1, walls fell. I'm quite confident, however, of the construction of the home I live in vis a vis earthquake stability - my walls are nearly 12" thick.

I get fungal/rot problems only during the peak of the wet season, and that's pretty much limited to powdery mildew, which is easy to keep in check. It's quite dusty, but most people grow tough xeric grasses in their yards to keep it down, and Datura and Epazote colonize everything, which tends to hold the top in fairly well, except when it gets really windy (which it does, especially when the seasons change over.) On very hot days, the main sport in this city seems to be "stalk the beer truck" - the local stores run out of cold "biggies" pretty fast - fyi beer comes in two sizes: regular 10 oz. small bottles, and large 28 oz'ers, which, at 75 cents a pop, are preferred.

You'd be surprised at how resistant Cortaderia is to this kind of environment - it's an ideal shelter plant for younger Agaves and Aloes. Of course, it also goes invasive really easily, so take my advice with a grain of salt.

[GermanStar]

Originally Posted by agavegreg

He says no to A. geminiflora!!! It's all over Phoenix in full sun and doing great!

'Sharkskin' has some A. asperrima (= A. scabra) in it that should help its sun tolerance. You might have to protect it until it gets established though. Don't want to recommend throwing anything out into Phoenix full sun this time of year without acclimating it.

It's been two weeks for the sharkskin and no hint of burn yet, although a rabbit ate one lower leaf down nearly to the core. I've placed a lawn chair over the plant from 11 - 2:30 about 10 of the 14 days, but that's more than enough sun to have burned some Agaves by now... I think it's gonna tough it out just fine -- as you said.

[GermanStar]

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