Which Oak trees grow in HOT weather?

I live in Tempe, Arizona where the temperature is 100 degrees plus (our highest was about 122 degrees in 1990) usually from late May through September. What kind of Oak tree could withstand these temperatures? Has anyone in the "Valley of the Sun" had success with an oak tree? We recently removed a 50 year old chinese elm and want to replace it with another large tree. Our elm was about 65 feet high.

Quercus arizonica Arizona white oak 60 ft/30 ft
Quercus dunnii Palmer oak 20 ft/15 ft
Quercus emoryi Emory oak 50 ft/30 ft
Quercus gambelii Gambel oak 10 ft/3 ft

Hardiness is rated for some by elevation. Please research your choice with elevation in mind.

The Q. emoryi sounds ok but it's rated for Zone 10. The Q. gambelii is beautiful, they grow a few hours north of the Valley where the summers don't get much higher than the 90's. Do you have any knowledge of Q. suber, the Cork Oak? I've seen one at the Phoenix Zoo (just 2 miles from us) but it appears to be stunted (they should grow to 70 feet), but it is planted near the asphalt walkway and may not get enough water. I just pulled out my Sunset Western Garden book to check on our zone. The book shows us as Climate Zone 13 but when I was assigned a zone when I signed up with this web site it shows us as 9a...I'm confused.

There are 3 hardiness rating maps currently in use. Sunset is one, which you know. There is the USDA map, which Davesgarden uses and the ArborDay Foundation Map. All three put Tempe at a low temp zone of 20 to 30 degrees. Sunset divides the country into smaller geographical areas. The USDA map has been unchanged for quite some time. The Arbor Day Foundation, based on their interpretation of statistical weather data recently (2006) broke with the USDA map and pushed some zones warmer. For instance My USDA zone is 5. My ArborDay Foundation zone is 6, one warmer. (Somebody tell my Hydrangeas!) To further confuse you the American Horticultural Society has gone further in identifying plant heat zones. Just how hot can a plant take it? That is important information especially in your zone. Take a look and see where you are.

http://www.ahs.org/pdfs/05_heat_map.pdf

As to the Cork Oak here is the information form the PlantFiles.
http://davesgarden.com/guides/pf/go/54410/

I'll keep trolling around for more tree information. There is an outstanding expert here who goes by the name of Resin - Wish he'd drop in and advise.

Thanks Snapple. You sound like a master gardener! I'll check out the links you posted. Do you have any idea if the Cork Oak has invasive roots? The Oak would replace our Chinese Elm that died; it was beautiful but the roots were everywhere, even broke through my cement enclosed flower beds.

Cork Oak is native to a Western Mediterranean-type climate (similar to e.g. coastal California), not sure how well it would adapt to AZ climate, as witness that one you mention at Phoenix Zoo. It is also a very slow grower even where conditions are good for it.

I'd go for one of the AZ native oaks mentioned by Snapple.

Resin

Thank you Resin. I need a tree primarily for shade since the loss of my Chinese Elm this year. I have a Shamel (spelling?) Ash that is about 7 years old and it's been an excellent tree, but even after 7 years it's only about 30' tall. I'll do more research on the native oaks.

I'd say Emory Oak would work well for you. Also, I'm not sure if the zone 10 rating you got for this Oak is from your sunset zones or the other more wide spread zone systems, but in the most used Arbor Day zones it's hardy from zones 6 to 10(maybe 11). There are some magnificent specimens at the Desert Botanical Garden in Phoenix, which are about 75' tall or so. Arizona Oak would work well for you also, but would be a much smaller tree only growing to about 25' to 30' tall typically. Mexican White Oak, aka Monterrey Oak, aka Netleaf White Oak(Q. polymorpha) would work well for you also. It's got relatively large lush looking evergreen leaves and will grow to 70' or 80' tall with time. A little smaller growing Oak with a similar look to it(although the leaves are smaller and not quite as lush looking as Q. polymorpha) as Mexican White Oak would be Netleaf Oak(Q. rugosa). It's native to your area and grows well in cultivation. It has very thick rugose leaves which look neat to me and the leaves tend to be cupped(the edges roll downward). It will grow to about 40' to 50' tall with time. Plateau/Texas Live Oak(Q. fusiformis) would work well for you. It loves heat and is very drought tolerant. It's also native to similar climates in Northern Mexico and New Mexico. It can grow to 50' or 60' tall in your climate. Another really nice Oak with a completely un-Oak like look to it which would work well for you is Silver Leaf Oak(Q. hypoleucoides). It will grow to about 30' or 40' tall with time and has long narrow, (mostly)untoothed, thick evergreen leaves which are a medium green to gray-green above and bright silvery white underneath. It's new growth is a nice silvery red in contrast to it's older leaves which is showy.

If you want a large leafed deciduous Oak, Bur Oak(Quercus macrocarpa) and Chinquapin Oak(Q. muhlenbergii) both will grow in that kind of heat. There are many large old Bur Oaks in Bakersfield, California (seen some in Barstow, CA too) which has a similar climate to yours and they are doing very well(many being 100 years old and older). Once established they are very drought tolerant and don't need a lot of extra water(even in your climate), although they'll grow much faster with extra watering. Chinquapin Oak is native to similar climates in New Mexico and Mexico to yours, but they do require more water in your climate than Emory Oak and some of the other Oaks.

If you want to get really exotic, you could go for one of my favorite Oaks, even though here in Kansas it's just a small shrub for me, which is Loquat Leaf Oak(Quercus rhysophylla). It will grow to 80' to 100' tall or so with time and has large evergreen leaves which somewhat resemble the leaves of a Loquat(Eriobotrya japonica) except they tend to be wider and a bit larger. It's new growth is a very nice red in stark contrast to it's old dark green leaves. It does tend to want a bit more water than many of the other Oaks though. This one you'd probably have to get via mail order though.

Gambel Oak is a high elevation Oak which struggles growing in low elevation heat and won't look that good even if it does grow for you. Palmer Oak(Q. palmeri, Q. dunnii is currently an invalid name for this Oak) will only grow to be a large shrub and may not get any larger than about 10' tall. The closely related Canyon Live Oak(Q. chrysolepis) will do well for you though. It has medium green evergreen leaves with a soft fuzzy yellowish underside to them and it's extremely heat and drought tolerant. It's native to AZ and it will grow to about 70' tall or so with time.

The Arizona Cooperative Extension has some relevant information about hardiness as it relates to elevation, but it is not zone specific. Apparently they havn't yet caught up with nomenclature changes?

http://ag.arizona.edu/yavapai/anr/hort/xeriscape/trees.html

The Arizona Cooperative Extension does have zone information. They tend to hide their light under a bushel there and finding the right Fact Sheet for tree choices has been problematic.
This is the link for zone information.

http://cals.arizona.edu/pubs/garden/az1169.pdf

This is the link for Maricopa County Extension. A worthwhile place to contact for tree reccomendations.

http://cals.arizona.edu/maricopa/garden/

This message was edited Jun 28, 2008 9:00 AM

I'd say from a look at the Arizona Cooperative Extension's website they have a lot of errors to correct and changes to catch up with. No kick on them, I'm sure with the booming population in AZ they have lots of things to deal with to just account for the huge influx of people probably contacting them with questions, etc. Their nomenclature is out of date and their size range for many of the trees isn't very accurate. 2 relevant examples that stick out are Gambel Oak only growing to 10' tall and 3' wide, while there are examples growing up in the mountains of the Tonto National Forest just a 30 or 40 minute drive up highway 87 from Phoenix of Gambel Oaks 40' tall and wide. I'd say Gambel Oak can range anywhere from 3' to 60' tall and wide depending on the population the acorns were collected from in the wild. Although a typical range would be 15' to 30' tall and wide. They also list Gambel Oak as being evergreen, which it clearly isn't and makes me suspect they've got the information on the hybrid Oak listed historically as Quercus x undulata(typically seen as a large hybrid complex involving nearly a dozen species, but with Gambel Oak as the center piece parent) with that of Gambel Oak. They also look to be listing a size for Q. palmeri(Q. dunnii) which more accurately describes the size for the hybrid between Q. palmeri and Q. chrysolepis, which there is a large area of this hybrid in Eastern and SE Arizona and not for the straight species.

I also notice the list in the first link is from Yavapai County, which is overall a much higher elevation mountainous, cooler summer climate(cool compared to Phoenix and the low desert) area than Tempe in Maricopa County. Prescott, the county seat, is typical for the county sitting at over 1 mile in elevation(5,368ft) compared to Tempe at only 1,183 ft. A very different climate in which Gambel Oak would grow well, while it won't do well in Tempe(the same for some of the other plants on that list).

I think their state zone rating looks to be very good and provides people living there in AZ with a much more accurate way of determining which plants might do well for them than the other national zone systems and it's very similar to the sunset zone system. All of the Oaks I mentioned should grow in the Tempe area(their state zone 5) with the proper care and maintenance.

Thanks all. The emory oak sounds good. Is this a slow-growing tree? Are there problems with invasive roots? My old Chinese Elm roots split our concrete sidewalk in several places; the elm's not a problem now, is was nearly 60 years old and had some strange disease, inside the trunk turned soft and spongy. We had to cut the tree down and ended up having to dig out the stump. When we were digging we found some type of grub, largest grubs (about 6" long and about 1.5" around...no kidding) I've ever seen and we were wondering if they could be the early stage of a Palo Verde Beetle. I'm hoping the disease won't be transferred to a new tree...my shamel (sp?) ash hasn't been affected.