Wrong forum

Is there heat zone information? I'd like to see a heat zone map. Also, I wonder what formula they would use to define it. High heat with cool nights has a different effect than the same high temp in the daytime without the nighttime cool down. Consistently warm night temps are the breaker here for many plants, including desert plants which tend to prefer that nighttime cool down.

There definitely is a heat zone map. Here's the AHS link:
http://www.ahs.org/gardening-r...

Donald ...

Yes, there is heat zone information available. In a sense, it further defines "full" sun. Full sun in heat zone 8 is more intense than full sun in heat zone 6.

I first learned about it from a book recommended by another ATP member, The A-Z of Garden Plants published by The American Horticultural Society. According to the chart at the back of the book heat zones are defined ad "Average number of days per year above 86F (30C)." I am guessing the formula is calculated the same way cold hardiness zones are calculated with no adjustment between day and night temps.

I have to look up every plant before I even think of purchasing anything for the garden because even tho' my temps cool off at night, gardening in a more arid climate with a high heat zone number truly limits the plants that will grow well for me.

Smiles,
Lyn

I found another site that allows you to enlarge the heat zone map for just your state.
http://www.gardeningplaces.com...
It would be nice to find one that allows you to enter your zip code, but haven't turned that up yet.

That's a good one Woofie. 120-150 days above 86F for me. That's prox 4-5 months of warm temps. I sure wish they would give the number of days of night temps above 65F to go along with it. That makes a difference in what plants do well here. Anything with alpine as part of its description may tolerate the lack of humidity and rain and warm days, but they prefer the cool nights. They can be chancy. Perennial Oriental poppies would probably do just fine for me except for the warm night temps. Also a lot of bulbous plants don't handle the continual warmth without a break. A lot of zone maps list them as hardy based on the cold zone map, but they aren't seen growing. I don't much use the cold zone maps because they are insufficient.

Eeek! 120 to 150 days above 86F??? I'm going to stop complaining about our snow.....
We only get around 30-45 days above 86 here, according to the heat map (and my own recollections ), although it's hard to tell because the map isn't quite detailed enough and we are in an area that appears to contain several heat zones.
Anything much over 72 sends me running for the AC.

It looks like a lot of plant vendors are starting to include heat zone information on their plants now. So it might be a useful addition to the database.

Thanks, Woofie! I starred your post and bookmarked the state-by-state heat zone map.
Heat Zone:
The average number of days each year that temperatures go over 86 F = 30 C.
(Apparently most plants are damaged above 86F.)

I also wish it was easier to find info about plants' needs for warmth expressed as "growing degree days" or "heat accumulation".

That is calculated by finding each day's average temperature (Max + Min / 2) then subtracting some base temperature like 10 C. Then each day's "degrees over 10 C" are added up over the whole season to see how much heat accumulation there was.

That's the kind of calculation that tells you some climate might be too cool for most tomato varieities to ripen fully.

http://en.wikipedia.org/wiki/G...
http://www.weather.com/outdoor...

I couldn't see the map well at the link above. This one was big enough for me to see:
http://www.upsidedownpatiogard...

I'm in the 120-150 range too.

Yeah, Tiffany. Bet you'd win on the humidity scale by a lot! I don't have to go too far east or south to find more of that.

Tiffany, thanks for that map ... much easier on these old eyes! I'm in the 120 - 150 days of temp's above 86ºF too and some days humidity to match the upper 80's - mid 90's but it seems winter is upon Florida pretty early this year; we never made it far into the 50's all day today and our low tonight is supposed to be 37-38 degrees with wind chill of @ 27º. Brrr ... I'm going to hibernate now.

I'm in 120-150, too. Donald has a good point--would be useful to have the low temperature ranges, as well.