Graham Porter’ gardening: Weather the weather to earn best results

Nov 21 2009 By Graham Porter

WHETHER the weather be fine or whether the weather be not; Whether the weather be cold or whether the weather be hot; We’ll weather the weather, whatever the weather; Whether we like it or not.

This apparently anonymous piece of poetry has been used as a tongue twister by countless generations and the weather still remains one of our favourite conversation starters. And yet, in our own gardens, the peculiarities of micro-climates, plant hardiness, frost pockets and much, much more still seem to a mystery to most people.

Our general understanding of the weather is based on weather forecasts in newspapers and on television and radio or, at the last moment, a quick glance out of the window to decide whether it is a shorts day, an overcoat day or a stay indoors day.

So, over the next few months, I am going to pick the weather to pieces for us gardeners and see what makes it so important to us and the plants we grow.

Plant hardiness has always been rather confusing because there is more than one system that can be used to determine a plant’s hardiness. The American system, known as the USDA system was developed by the United States Department of Agriculture to help growers and gardeners understand whether a certain plant might survive in their region – it has 11 different zones based on the lowest likely winter temperatures, Zone 1 being the coldest down to -45ºC (-50ºF) – brrrrrrr!

The Royal Horticultural Society’s system is much simpler, being based on only four zones and we can see these in use in any of the popular RHS Encyclopaedias, represented by a star. Three *** indicates fully hardy (down to –15ºC), two ** indicates frost hardy (down to -5ºC), one * indicates half-hardy (down to 0ºC) and a glasshouse image indicates frost tender (not hardy below 5ºC). The European Garden Flora system has seven zones using a similar format to the RHS. To see an overview of these visit www.theseedsite.co.uk/hardinesss.html.