the uncertainty of climate zones

thanks to the information font that is twitter, i came across an interesting article on how the USGA is revising the plant hardiness zone maps due to global warming. this isn't a big surprise, except perhaps in that it took so long (the last revision was in 1990).

now personally, i've never relied much on those zones. partly because here in northern california, you find a multitude of microclimates often even within a single yard. my current location, for example is a zone 8, but because i have an enclosed patio with full afternoon sun exposure surrounded by a concrete parking lot and sheltering trees, i'm probably closer to a zone 9 with the high temperatures of a zone 10 (in summer it can be an oven out there).

which points out another inadequacy of the current zone structure: it focuses on lows and largely ignores highs. just because a plant can't take freezing weather doesn't mean it can handle scorching heat. take for example the artichoke, which loves the temperate northern california coastal marine zone for its fog and even, year-round 50-60 degree temperatures.

also, because i am often taken with plants outside my zone, i have found that plenty of plants, given the right placement and attention, can survive just fine outside their zone (often by several numbers).

i am curious to see how the remapping unfolds, but for me, i'll stick with the sunset western garden book which does a much better job of accommodating the intricacies of our california microclimates than zone mapping does.