Norma, I hope I dont give a 'dumb' answer, but have you ever lived anywhere else than zone 9?
I guess I'm wrong; I thought you were in florida . . . .
Sherry, who is in zone 5a; NOT the same as zone 9. (though sometimes I dream about zone 9)

(or do you mean the southeastern states of the u.s.?)
I probably dont understand what you are asking . . . . (a glass of wine after a busy day can do that)

The USDA zone system is based solely on average winter low temperatures in a region. There is no other data involved, which is why Sunset magazine has created it's own zone system which includes other climate factors: latitude, elevation, ocean influence, continental air influence, and mountains, hills, and valleys, all contributing to local conditions called microclimates.

This is the USDA zone hardiness map. You can click on a region and it will zoom in. Notice that all the States North of Florida are in colder climate zones than coastal California 9a and 9b.

Obviously there can be many different kinds of climates that are USDA zone 9. Conditions in Florida zone 9 and certainly different than coastal California zone 9.

From the Sunset magazine page linked below: A plant's performance is governed by the total climate: length of growing season, timing and amount of rainfall, winter lows, summer highs, wind, and humidity. Sunset's climate zone maps take all these factors into account, unlike the familiar hardiness zone maps devised by the U.S. Department of Agriculture, which divides most of North America into zones based strictly on winter lows.

Here are Sunset magazine zone maps. Click on your region in the list on the left to get more detailed maps and descriptions of growing conditions.

Hope that helps!

Brad

For example..

In just Arizona, it can be a zone5a in Flag Staff to a zone 7b in Phoenix in just 4 hours..:-)

Very good question actually Norma..:-)

Take care

Mike..;:-)

The other people have answered you pretty well, but I will add my 2 cents worth. From what I know, you are definitely in zone 9, just like I was in New Orleans - winter lows between 20 and 30 Fahrenheit. In fact, I should think it never goes below 25 for you. And expected winter lows are what the USDA lows are based on.

So a zone 9 is the same no matter where located, we have gone down to 20F for 5 early mornings, about 2 years ago. Thank goodness my plants had not been watered.
That made sense to me, but every one seems to think because they live in the eastern states it is different, the plants need different care. I know other things are factored in, I have read these books, and I have 3 of them on my shelves right now. I still can't figure out why then they use peat moss, unless that is all that is obtainable. I think we are going to a higher pumice content, no coarse sand at the HBG. Now I worry about the rain damage especially if it turns cold after this storm. Norma

Hi Norma.

For a while now you have been saying your weather has been cold..Sheesh.
I think I will think twice before moving there..lol
If the weather keeps getting colder and colder there each year, I think they will have to make new zone maps, and put you in the same boat as us New Englanders...Now I see why you have to keep yours dry this time of year..
If you use sand, I suppose that would compact any air space in the soil, and stay wet too long?

Look at the brighter side. At least your sun is a lot warmer than ours, and you will be getting the flowers, birds, warm weather a lot faster than us..:-(

It is only going to be 40 today...

Take care Norma

Mike..:-)

It is an important question, but no one that has lived in the southeast and been at all to southern CA would consider the climate even remotely similar regardless of what a zone map says so the potting mixes would potentially be different, although fast drainage for both. It is important to keep in mind summer rain vs winter rain, massive humidity differences, etc. I grow very few caudiciforms and succulents, but do have a lot of South African bulbs/geophytes....I never use peat for anything.

We have not seen 40 since a freakish warm week in Jan so I can not wait to see the big 4-0 when it happens :o) Dan

Norma, as has already been explained here, the USDA zones are based solely on the averaged lowest winter temperatures for the region, so the normal lows are the main thing in common between very coastal parts of Louisiana, south Texas and parts of Florida. As these are all year round or predominantly summer rainfall regions, and more normally dryer in winter than in summer, they have more in common with each other than with California, with its wet winter/dry summer Mediterranean Climate. The other very basic difference between East Coast/Southern USA zone 9 climates is that they are continental influenced to a much greater degree than coastal California; and this results in warmer summer nights, and typically cooler winter days and nights, and a greater tendency to suffer huge swings in temperature over short periods of time. The Pacific Ocean tends to have a much more moderating influence on California zone 9 climate, keeping it cooler on summer nights, and milder in winter as well.

When making up soil mixes and trying to predict how a new plant will do, it makes sense to look at the climate where it comes from. Does it get winter rains like California, or predominantly summer rains? Does it come from an area that has hot nights and high humidity, or is it tolerant of dry summers and low humidity? These are the sorts of reasons that a genus like Aloes from South Africa's zone 9 locations vary widely in how they do here in California. The species that come from winter wet parts of South Africa generally do poorly in south Florida, yet thrive here. Some of the species from the subtropical parts of Eastern or Northern South Africa just don't like our wet cool winters, others will tolerate them if given extra good drainage and protected from frost.

The other huge difference in zone 9 climates occurs with temperature gradients across the state of California. Some things that do very well in southern California with the warmer winter days and dryer winters in general, do poorly here in northern California, although we can both be USDA zone 9 climates. A perfect example of this is one of my favorite plants, Euphorbia tirucallii 'Sticks on Fire'. I have yet to get this plant to thrive through a winter here in San Francisco, Berkeley, Oakland or Alameda where I have tried them outdoors year round, as it is always two steps forward in the warmer months, and one or two steps backwards in the winter, when they rot out and lose foliage mass. I know someone like Stan will say that he grows this in his own garden and it does just fine, but they never look anywhere near as big, healthy, full and colorful year round up here as they can down south.

On the other hand, our higher humidity in summer and fall, general lack of regular Santana type fall/winter hot drying winds, and cooler temperatures in general can give perfect conditions for some plants here in the San Francisco Bay Area that don't like it hot and dry. Many Echeverias, Aeoniums, high elevation tropical cloud forest plants, etc do much better here than they do down south anywhere except right along the cooler/milder coast.

So obviously gardening conditions vary tremendously even with the same USDA zone 9 conditions, and it helps to know whether the plants you want to grow prefer a Mediterranean climate or a continental one, summer or winter rain, hot humid nights or cooler coastal ones, etc, etc. Trying to determine what the climate is like where the plant is native goes a long ways towards predicting what conditions it might prefer, but some plants have broader capabilities of taking whatever you give them. In particular, I have been amazed how broadly tolerant some South African plants are, especially those that are native to the Eastern Cape regions or the Drakensberg Mountains, where the climate is highly mutable from year to year, and many common plants such as Strelitzia reginae or Tecomaria capensis do as well in Florida as California, and also in pure deserts as long as they get enough water. Plants that tend to experience wide fluctuations in rainfall patterns from year to year, as well as extremes of temperature, often prove to be the most adaptable to growing in gardens.

It is also amazing to me to see how so many annuals and short lived perennials that come from Namaqualand and the Western Cape, and in habitat are only winter growing species that die off after blooming in spring, can grow well here in coastal California as any season annuals. I have learned a lot about this from having worked at Annie's Annuals and helped with planting of their display beds, and have come to love using many of the various annuals that Annie Hayes has brought in from Silverhill Seeds and others. It helped that I had had the chance to see many of these same plants in full bloom on a wildflower tour of the Western Cape, and saw where they grew and what the conditions were like.

You have a huge advantage over most of us in that you volunteer at the Huntington, which has one of the premier collections of succulents from other USDA zone 8/9/10/11 areas around the world. Their collections tend to favor those plants that are best adapted to the winter wet/hot dry summers of their location, and do less well with more frost tender species that are intolerant of occasional broad swings in temperature in winter and summer. Some of the differences become obvious if you compare what does well at Quail Botanic Garden or the Mildred Matthias Botanic Garden at UCLA, both of which are more coastal influenced, with the Huntington's collections. Plants and their performance will vary yet again if you travel north to our SF Bay Area botanic gardens and see how these same plants do in our version of USDA zone 9b/10a conditions. Distance from the coast seems to have a more profound effect on how the plants grow than latitude when comparing northern and southern California, with the Ruth Bancroft Garden out in Walnut Creek having succulents and cacti that more closely resemble what is grown at the Huntington than the San Francisco Strybing Botanic Garden collections where it is so often foggy and cold in summer.

My blood has gotten thin living in California. I think the lowest it has been this winter was around 40. But even when it is in the upper 50's I am shivering. Does anyone know of a website that gives you the highs and lows "so far this year" of the city you are in? I can't seem to find anything like that on the weather site I use.

(happily in zone 24 not 9 or 10)

Bahia, all I can say is WOW..What a very informative post.

I have one question to ask? Maybe Norma can answer too..

Could this explain the reason why local nurseries like mine and big box stores sell the same ole same ole plants with not a huge varieation of selections and or unusual plants?

Do you think they pretty much sell what is favorable to grow in our zones regions?

What kind of succulents and cacti can handle so many drastic changes in some of our zones, and yet perform well indoor and out? Like you said, there are many areas that can get totally different weather, overnight, and sometimes I wonder what plants can handle this..

For example:

Aloe...Would a person most likely loose their plants if they are use to a hot and arid climate, when one something happens, freak weather takes over for days in that area in which it rains for days along with cool temps in in-ground?

Thanks..

Mike..:-)

Mike,
It sounds like you are at that stage when local nurseries and big box nurseries are too limited for what you want to grow, and you need to make the transition to mail order specialty nurseries. Big Box and local nurseries will vary in their selection based on what the market demand is, and whether there is an educated, more adventurous buyer for the store. I can speak from experience that it varies by location, as there is one Home Depot in particular here in the San Francisco Bay Area that consistently has the most interesting and diverse selection compared to any other location. For those locals, that would be the San Rafael Home Depot in Marin County.

To answer your general question about a specific Aloe's adaptability to your conditions, it is hard to generalize about how they will do in your location, as you don't have the basic climate that supports them as outdoor plants, nor are plants grown indoors in winter and outdoors in summer going to exhibit the same degree of hardiness to unexpected weather that the same plant hardened off outdoors will exhibit.

To give just one example, succulent plants that I grow such as Bulbine frutescens, Aloe striata and Aeonium canariense all tend to be somewhat frost tender in my local conditions because cold is often accompanied by very wet winter storms. I tend to get damage on all of these at 30 to 32F temperatures, whereas in drier winter locations with less winter rains and much warmer days, such as in Tucson, these plants may easily take 25~26F without any signs of damage,(except for the Aeonium, which just doesn't like desert heat).

As to what succulents will do best under your local conditions, you'll be better served by speaking with local specialty growers, and find what has worked best for them. I can really only speak to which plants do well under California conditions here in northern California, but also have some experience with succulents from South Africa or Mexico which I have also seen do well in tropical locations such as Brazil, Malaysia, Indonesia and subtropical desert climate of Saudi Arabia; all places where I have lived and worked professionally. As one example, the Bulbine frutescens is so widely tolerant of different growing conditions that it is well regarded in both subtropical deserts, Mediterranean climates and the wet, humid tropics, but probably grows best and flowers the most here in a Mediterranean climate, where it can bloom all year round.

If you have a local Cactus and Succulent Society that you can join, or a local botanic garden to join as a member to get more specific growing information, that all helps. If you have a specific interest in Aloes in general, and need to grow them indoors in winter, then you will probably gravitate to the smaller growing Madagascar species and hybrids, which take up less space, but are usually more tender to cold and more specific in their needs, as Madagascar has a real range of climates based on rainfall and altitude.

My own focus on Aloes is more related to the ones most easily grown outdoors year round in my climate, and that have the more interesting forms or flowers, with a bias towards the showiest bloomers and the larger growers. I also tend to specialize in those that clump easily or are fast to regrow from cuttings, as these lend themselves to landscaping projects with lower budgets, for instant effects. I particularly love species and hybrids that I can replant directly as unrooted cuttings, and know that they will simply take off for mass bloom. Plants such as A. arborescens in the different color forms, A. striatula, A. maculata are particularly useful in this regard.

One dwarfer growing hybrid that I would highly recommend for container culture and is probably little seen outside of California, is the dwarf everblooming Aloe 'Johnson's Hybrid', which truly does bloom all year round here in the San Francisco Bay Area, and is very showy to boot.

Good luck with your hobby, and if you can squeeze in a foreign trip to South Africa or Mexico to see your favorite plants in habitat, it will definitely reward you with a better understanding of the succulent growing possibilites and the range of plants that you might get interested in. I might also steer you towards one of my favorite local nurseries that does mail order country wide and has a rather diverse range of succulents to choose from:

www.anniesannuals.com

Good luck with your interests, and sorry I couldn't really be more specific about plants for your conditions! I don't grow any succulents indoors except for a few Gasterias and Kalanchoes, and most everything else is outdoors year round and must be able to take the occasional 28F frost and wet winters of Berkeley.

As others have already said - the USDA hardiness zones are essentially meaningless.

A Zone 8 somewhere in the Southwest is a completely different entity from a Zone 8 in the East. Here is a general and simple, yet profound example:

It may be very cold for 1 or 2 or several nights somewhere in the SW. But it generally will warm up very quickly during the day. Cellular damage can be reversed.

Somewhere in the East it may not get any colder than the same low temp in the SW, but it will be cold for many more days, and it will not warm up much during the day. Plants in this situation are unable to recover from the cold damage.

Folks try to be "zone pushers" with things like cold-hardy Palms...but it is a difficult task, not because of the absolute coldest temp, but because it stays cold (and usually too wet) for too long.

x

I don't think one can really say that USDA Zone designations are meaningless, as they do give some idea of where to start when considering a plant for your garden. On the other hand, I would definitely agree that a plant being designated as hardy for your particular zone doesn't insure that it will actually do well for you, it is just one part of the puzzle. For sure, comparing different parts of the USA with the same zone designation will be a meaningless exercise if you assume that plants designated for that zone are interchangeable from one region to the other.

Like it or not, the nursery industry and plant labeling have been set up to follow the USDA zone ratings, and it is probably here to stay. The fallibility of this simplistic zone designation and how unreliable it proved to be along the western Pacific Coast of the USA is probably the major reason that zone designations such as the Sunset zones were created; they more precisely reflect factors beyond winter lows that make regions climatically distinct. I don't know how precise the Sunset zones really are as they are applied outside the western states, but they also exist for the rest of the country, and magazines such as Southern Living tend to use them.

In short, Zone 9 in California is the same as Zone 9 in Florida only in the fact that they share the same minimum temperature ranges. All other variables such as humidity, for example, need to be considered as well.

Christopher

You betcha everything must be considered to adapt plants to youe conditions, or you adapt to theirs or they won't live, that is why we are switching to almost pure pumice to grow them in, We have dry hot weather in the summer, and cold down to 20F once in 20 years. Pumice holds water, but drains well. Our coarse sand 30% hold too much water, even in the winter we have low humidity except when we expect rain. The plants dry out in a week because of the size of pots that we use. Plants that need more water we use larger pots, All of our Lithops are in tiny pots 4" deep and we don't change the soil, I don't remember that in the near 20 years that I have been there that we changed the soil. They are grown in pottery stoneware and not plastic pots in the protected conservatory, greenhouse, which is not heated. We adjust conditions to what our plant needs, the plants out side in the garden slowly day by day adjust to temperatures as it gets colder or hotter, they are in open ground and are not captives in a pot. I can't stand temps. below 68F I actually start to sneeze, I am cold as I sit here not and the temp. is around 72, but I am thin and gotten older, and older people need more heat I turn up the heat, Your cacti needs cold and dry in the winter to flower in the spring, amd most succulents need warm and dry, other than Crassula need cool and dry, but not even all of them, and this also a reason why a name is so important to make that judgement. That is why we like to collect them they are all so unique in their needs, and you had better know the difference. I'm not proofing this, Norma

This is a really interesting subject. USDA has Savannah in Zone 8. My mother lives in middle Georgia, 3 hours away, and is also in zone 8. There are many plants that are perrenials for me here in Savannah, but are annuals in my mother's area. Where plants are concerned, our areas vary greatly when it comes to weather, temperature, rain, wind, and soil type to name a few. We have very sandy soil here while my mother is blessed with good old Georgia red clay.

The Sunset Climate Zone Map was very interesting. I had not run across that one before. You may also want to type in your zip code to check out your hardiness zone at the Arborday.org site (link below). They have Savannah in 9 and my mother in 8.

Based on most of what's been stated here, the zone maps out there are pretty much just guidelines. Based on living here for 10+ years, I've decided that I'm in Zone 9.

Great thread!

How does one factor in the variables in pot culture?

For example, both California and Florida are in Zone 9, but Florida is more humid and that humidity has to be considered in pot watering.

How is humidity considered in determining how much to water in pots with fast draining soil? Would knowing the relative humidity help to determine this?

tinyplants: humidity is but one of several equally important factors to consider in pot culture.

Wind can also increase transpiration considerably, as can direct sun heating the soil.

The nuances of pot culture are learned and acquired over time as you observe and understand your conditions and how to manipulate the variables.

As far as zones are concerned, growing in a pot definitely reduces the plant's zone tolerance. In-ground plants at cold temperatures have the added insulating effect of the surrounding soil. In a pot, the roots are more quickly exposed to the dangerous cold.

For large pots, I like to add a thirsty annual - something like impatiens or petunias. When they start to wilt, then the soil is getting dry. They make good soil moisture indicators.

For smaller pots, grow a small annual in a similarly sized container with the same soil and environment, and use it to cue your waterings if you aren't sure.

x

I call that my "canary in a coal mine" plant x. I don't have them in the same pot but I like to have at least one plant that is very obvious and showy when it is reaching that temporary wilting point. My current "canary" is Nicotiana langsdorfii. When I see it wilting it reminds me to check on my other plants as well.

tiny I would agree that humidity plays a part in in watering needs (my experience in California vs. the east coast is that things dry out much faster here) but container culture can be so variable I don't really think you can have a set schedule. You have to keep on top of it much more than plants in the ground because things change so rapidly. A plant that looks perfectly fine in the morning can be in danger much more quickly if it is in a pot.