Jim Carlock wrote:
"Wolf Kirchmeir" wrote:

Zone? Climate? Here in Mid-Northern Ontario, Can.
Zone 4b, hot and himid summers with two to three
rainless weeks on occasion, well-protected garden,
lemon balm is a perennial.


Thanks,

I'm in Tampa, FL. The average daily year round temp
is something like 72º F. We get rain when a hurricane
gets close enough. It freezes very rarely here. Might get
two nights a year where the temps might come close to
freezing. August was a dry month. September was dry
as well, even with hurricanes in the Gulf of Mexico.
[...]

Your area may just be too warm for lemon balm. Plants are surprisingly
adaptable to different climates than their native ones, but there are
limits.

"Perennial" just means the plant survives from year to year - no winter
kill (eg our wild violets, which are white.) "Annual" means it lives for
a year, and grows from seed the following year (e.g dill.) "Biennials"
have a two-year growth and reseed cycle (eg, foxglove.) Some perennials
have a relatively limited life-span of a few years. Lifespan for plants
varies a lot: a birch lives about 30-40 years, while an oak can live for
a several hundred years, and a bristlecone pine can live for several
thousand years.

Some plants that are perennial for you in Florida are annuals for us -
our winter kills them. But if we bring them inside for the winter, they
survive just fine. We have an oleander, a bougainvillea and a hibiscus
that are going on 20 years old. All spend the summers outdoors and the
winters inside. All three are perennials from central California
southwards. We also have to bring in a variety of bulbs and corms, else
the deep frost will kill them.

Conversely, apples and roses do not like heat - subtropical is about as
warm as some varieties will tolerate, other varieties don't like that
climate at all. Our birch trees won't grow down where you are. And so on.

One final thought: if it's not climate, it's soil type (acidity.) Can't
recall whether lemon balm wants acid or basic soil, though.

HTH