“But it said zone seven.” How many times I have heard that complaint in my career I’ll never know. For certain, we all want a simple easy guide or set of instructions. I don’t have a problem with that. I do have a problem when folks decide that “zone 7” covers all the bases in a very complicated system.
To be sure, the USDA Cold Hardiness Zone map does deliver very useful information. However, it refers only to our average winter low temperatures. No more, no less. All veteran gardeners in Texoma know that we are most likely to witness stress or even death in new plantings during July and August. More so than any other time. I wrote about the “yellow turning brown” leaf syndrome last week with good reason and intention.
Cold hardiness doesn’t cover heat stress. There is now a Heat Zone map that was published over twenty years ago by the American Horticultural Society. Sadly, I have only read one gardening magazine (so far) that used it in plant descriptions. I am still waiting for someone to walk in and say, “But it said Heat Zone 9.” Hasn’t happened yet.
The Heat Zone map looks drastically different than the Cold Hardiness Zone map. In fact, Zone 9 covers most of Texas including the Panhandle. The United States Heat Zone map shows the number of days above 85(f) in any given location with Zone 1 being the snowy tops of the Rockies (zero days) down to the tropics in Zone 12, (210 days or more). Here in Zone 9 (121 to 150 days) we experience nearly half our year above 85(f).
This gives us another useful tool in the garden shed. These zones, (heat and cold hardiness) also cover a whole range of ecosystems from dense forests to deserts so we obviously need to look at rainfall and humidity as well. You can do a “google” map search and get all this info and a lot more. Climatology is a very broad and extremely interesting science… Especially these days.
So, the info is out there but just isn’t found on most plant tags or catalog listings. For instance, if you search for the latest USDA Plant Hardiness maps you will find that we are no longer in Zone 7. If you live south of the Wichita Mountains you are in Zone 8 with average winter lows between 10 and 20(f). This is due to the milder winters we have had the past thirty years or so. Yes, the climatology folks update the averages fairly often so new maps are drawn. However, we don’t often see these updates on plant tags, seed packets, or most catalogs. Why not?
The answer, pure and simple is time and (mostly) money. It is much easier on the budget to keep printing what you already have locked in. Plus, space is valuable and limited so you can’t possibly give all the info a novice gardener needs much less answer all the questions they might have. Like I said, things get pretty complicated especially when you are working mainly with non-native and man-made hybrid plants. I suppose that is why people like me get to write columns and are sought out by other media when the going gets rough.
So, knowing the plant tag said Zone 7 doesn’t help you at all in August. If the hot and dry gets prolonged, we are all in trouble. Remember 2011? Personally, I was real happy that my property was not on fire that entire summer. Believe it when I say I was constantly checking the sky west of The Falls every day. Nila and I were evacuated once but (God bless our fire fighters) we did not burn. Many were not so lucky.
We do have a very large Heat Zone map stapled to or front desk at the nursery. Most folks don’t seem to notice but I am happy to refer to it every chance I get. As I have been writing today I am thinking we need to get more maps concerning climate and eco-regions printed and visible at the nursery. Knowledge is truly powerful. Somebody has to lead so others can follow. I promise to get that done as soon as time and money allows… Right!!??
Just in case you aren’t thoroughly confused yet I want to remind you that all these maps and such are just averages. If you watch the weather very much you know how many times they say, “Above average and/or below average.”
Well, we just had another cold front push through this morning. There were some hit or miss showers around yesterday and again today. So far it has not been enough to wet our rain gauge let alone make mud but we welcome every little bit. Cloud cover and some cool breezes for us all.
I’m not gonna stick my neck out and proclaim a mild summer after a wet and mild spring but it really hasn’t been too bad so far. The averages do show that our temps begin to moderate in the second half of August. Come visit us now to see what blooms in summer and what will bloom in fall. Watch for those late summer lilies that pop up with bright red flowers to tell us fall weather is near. Hope we get some rain…