I noticed reading Lee Reich's Landscaping with Fruit, that his entries include an AHS Heat Zone reference.
When I Google's AHS Heat Zone, I got no results. So obviously this is a secret that people gardening in dry or tropical heat areas should know about.

AHS stands for American Horticultural Society. And the zones refer to the USDA hardiness zones most people are familiar with. For example, most of Alabama where I live is in Zone 8. The zone is supposed to describe the kind of plants that can be grown within that area.

There is an explanation and link to the AHS Heat Zone map here: You can download the AHS Heat Zone map from this page.

http://www.gardeners.com/how-t...

Other American Horticultural Society Gardening Maps can be found here: http://www.ahs.org/gardening-r...

HEAT ZONE MAP:: http://www.ahs.org/gardening-r...

I've heard of heat zone maps but haven't seen them mentioned much. I would think that they'd be invaluable to those living in warmer zones.

There are a number of plants that simply would not grow here in Alabama: peonies (some claim to have grown these), lilacs, tulips, amalanchier, apples . . .. I haven't checked crab apples yet. So the heat zone map will save a lot of trial and error.

I wonder if you're season is right for avocados or pears (peaches requiring a lot of work). Kind of a bummer knowing that it's too hot to grow certain things, even in shade. I did hear on one of Dave's podcasts about a new variety of apple that would grow in east TX but don't know how similar that climate is to yours.

Gloria ...

I happen to know more about roses than any other plants, but I had thought I wanted to used heucheras to create a foliage garden using the various colors of foliage to create contrast and texture. They also tolerate poor soil and have few plant diseases. Sounded pretty good to me.

Heucheras are rated in the AHS A-Z Encyclopedia of Garden Plants to be viable plants in Heat Zone 8, which is where I garden.

Typical of me, I started doing some research on the location of where the species grew and the lineage of the plants on the market ... especially those marketed as being heat tolerant and created a small database. I also checked many of the sites selling heucheras to identify which plants they considered to be heat tolerant.

My very, very basic research showed me a major flaw in how Heat Zone information appears to be presented. (I am going to stick with the heucheras for now because my database is readily accessible to me.) When heat zone information is supplied for a plant, it seems almost like a "stand alone" variable, but plants that can survive and thrive in a humid heat zone 8 will struggle in an arid heat zone 8.

Back to the species and the lineage. Most of the huecheras said to be heat tolerant contain H. villosa, which is found in the southeast US in humid climates. Heucheras that are heat tolerant in an arid climate generally contain H. micrantha, which is found in the more arid climates of the western US. (Note: H. micrantha is native to Trinity County where I live.)

I think heat zone information is vital to plant selection as it is the heat of my summer temps that has a more detrimental impact to my garden than the cold of winter.

Smiles,
Lyn

Pears do very well here, so Ill just except that apples belong somewhere else. They do show up on the stores, but usually soaked in shellac. Apples do grow in the mountainous areas of East Alabama. We had avacadoes in California--I used to ride my bike through an avacado orchard on the way to school. I doubt if they would grow in Alabama because of the humidity. In fact its even difficult to find an avacado that isn't over-ripe in the stores. They might grow in a green house. I have started some from the seed, but never got them to grow to fruiting size.

Rose Blush: We posted at the same time. I think its true that not everything designated as a zone 8 plant will actually grow in zone 8, because of aridity/humidity, sun/shade or other limitations. Figs grow well here and in California, but avacadoes don't because probably of the humidity.

Story: Alabama was once part of the French Territory. The city of Demopolis (near me) was ceded by the French governor for the purpose of growing "vines and olives". Well I guess vines and olives grow well in France, but they don't grow that well in Alabama.
We do have a native type of grape: muscadines, but grapes do better in Northern California. And olives do not grow here. So the wrong trees will not grow--even if mandated by the government of France.

heucheras.
http://parkseed.com/product.as...

I think these might grow here. But they are not common.

I noticed the same thing with Heucheras and I'm in zone 5. It's not the winters here that do them in but the summers. I think I've killed 7 or 8 (at least) and won't buy them (especially at current high prices) unless I've researched their parentage. A kind person over at DG recommended a nursery specializing in Heucheras better suited to hot summers with the nursery acknowledging that a lot of gardeners have issues with certain Heucheras.
So no avocados in AL. Didn't realize they need drier air.

Maybe they would be adapted better if you grew them from seed?

I started some H. 'Palace Purple' from seeds years ago. They self-sow a few babies every year if I'm not on top of cutting back the bloom sprays. They are the toughest Heucheras I have and even grow in mostly sun, turning some really nice shades of bronze and copper. I can even cut them back and they'll regrow new leaves. They do get pretty big as well. The leaf shapes vary as well so it's fun to see where they'll turn up. I've even passed some along to other gardens.

Thats what's fun is to have some to give away.

Oh - if I didn't give 'em away, I wouldn't have room for new plants. I can be a plant pack-rat as I hate throwing viable plants away. I get self-sown plants from a Caryopteris hybrid that I sometimes pot up and pass on as well.

Cindy,

'Purple Palace' has certainly passed the test of time. I hope to add it to my garden when I finally have I get the area where I plan to site the heucheras cleaned out. It has H. micrantha as the seed parent, which is naturally adapted to dry summers.

But I ended up having to shade two of my heucheras last summer to avoid leaf scorch even tho' they were planted under my dogwood tree. I think that was more the impact of the drought than poor siting.

Smiles,
Lyn

I noticed the park seed was a micrantha variety.

Rose - some of my purchased Heucheras came back happily from winter but started declining when it got hot during the summer. No amount of water would save them and they were in mostly shade.
I will have to do more checking into Heuchera varieties but am also hoping to plant more edibles rather than more ornamentals.

Cindy ...

You are correct. The plants that are used in the breeding program that are adapted to hot, dry summers usually contain the species found in similar conditions.

I had to build my soil first before I could grow anything and now that the drought is over for my part of California, I am ready to experiment with edibles again. I didn't plant any new plants during the drought because they require more water to get established.

Smiles,
Lyn

How long has your area been in the drought? Are your water levels back up to normal? And how did you build up your soil? I'm curious as I'm getting ready for spring cleanup (low 30's and snow here today) and want to incorporate some new soil-building practices before planting anything.

Cindy ...

I'll have to get back to you later. I just have to get outside and get some work done.

Smiles,
Lyn

California has been in a severe drought for three years and, now, is going into the fourth year. It will not impact my garden in Trinity County this year as we have gotten sufficient rain to wet the soil down deep which was my major problem last season.

No, our water levels are not back to normal. Trinity Lake is less than half full and there is no snow pack in the Trinity Alps. Since this county is defined as a "county-of-origin" that means we won't have water to send down south. The water politics are just ugly.

Building the soil: This is the first in-ground garden I've ever had and I really didn't know what I was doing at all. I still don't, in my opinion. I still have a LOT to learn about soil.

My primary planting area is what I call the house pad level in back of my home. I have a no-till garden. A good thing because when I started this garden, I couldn't even use a shovel to dig a hole. I had to use a pick. Now, I can dig in the beds I've created with a trowel. I have never dug anything into the soil. The change in the soil structure came about because for years I have hauled in organic material and placed it on top of the beds twice a year and just let it decompose.

Spring has arrived six weeks early this year. Normally, I would not be outside working, yet. Our last frost date is officially the end of April, but I let the forsythia tell me when there is no more danger of frost. This year it bloomed near the end of February, so I am playing catch up big time.

I've been weeding like a crazy person because we never got our sub-freezing night temps to kill off the weeds this year. I started pruning the roses near the end of February and now I've got to get my spring mulch down.

What do you plan to improve your soil ?

Smiles,
Lyn

I'm currently trying to solve a couple of issues. I have multiple large garden spaces under mature oaks. I do the traditional lawn raking in the fall, shred those leaves and hold them for the next year's mulch. Also employ the lawnmower to bag shredded leaves mixed with grass clippings (only use the bagger when collecting fall leaves). The garden beds don't really get cleared of fall leaves until the following spring because leaves are still falling at Thanksgiving. After being wet and weighed down by snow over the winter, those leaves form quite a mat. In the past, have always cleared those away and put in a huge yard waste pile along the back slope of my yard to mitigate erosion. Takes a couple of weeks to accomplish and leaves the ground bare between plants. Trying to find a happy medium this spring to improve soil quality and reduce labor.