Hi, All I'm new here, and from Scotland in the UK. Your forum doesn't seem to work in the same way as my familiar one from home. So please excuse any mistakes or breaches of etiquette. Also any spelling mistakes. It really annoys me that even my British English spell check at home gives me U.S. spellings. I ignore it, so I will ignore yours too, if you don't mind, and go with the way I was always taught. Latin names for plants should avoid confusion for the most part, even though many plants have been re-classified over the past few years. I would love to discover more about growing plants in the U.S, and for you to de-mystify things for me. The first question I have is;- What are growing 'zones'? I see them listed for plants, e.g, 'zones 3-8'. And can I apply them to where I live?
The zones are based on average minimum winter temperature (scale below); most of the UK is zone 8, but zone 9 on coastal fringes and zone 7 in upland areas (see map below). The main problem with the zone system is that it doesn't take any account of the difference between winter and summer temperatures: the USA (except for the west coast) has a strongly continental climate, with a large difference (cold winters, hot summers), while Britain (and also the US west coast) has an oceanic climate (mild winters, cool summers). This affects the range of plants that can be grown, some plants need the hotter continental summers and don't do well in Britain, while conversely, other plants do well in Britain's oceanic climate but can't be grown in much of the USA even if the winter temperatures are about equal. The other point to bear in mind is that the zones are based on average winter minimum: take the coldest temperature reached each winter over the last 50 years, and the zone is from the average of all of those. Of course some winters (e.g. 2010-11) are colder than average, while others (e.g. 2013-14) are milder than average. Losses of tender plants are inevitably concentrated in the bad winters.
