Growing Map - Europe
Where can I grow delphiniums in Europe?
As with the United States, growing delphiniums in Europe becomes easier the further north you go. We have compiled this map, which is a rough guide to regions likely to be suitable for growing our delphiniums, using climate and natural vegetation data, weather maps and personal reports. The map is a general indication only and there will be considerable local variation. The main deciding factor will be the number of days of extreme heat (say 30DegC ad above) in summer.
Ideally they should not be subjected to temperatures in excess of 80degF for long periods. However, we have found both from our own experience of growing in hot houses and from the experience of gardeners in the USA and Canada, that our New Millennium Delphiniums will perform well where temperatures reach 86degF for an average of no more than 45 days during the summer. These general areas are coloured green on the map. Best results are obtained where care has been taken to provide shade, or dappled shade from the hottest summer sun and if this is done our delphiniums should be truly perennial, lasting several years.
In areas coloured terracotta New Millennium Delphiniums may be grown as an annual, or at best a short lived perennial. In these areas the plants must definitely receive afternoon summer shade and efforts be made to keep the roots cool (straw mulch etc). Nonetheless, good management can still be rewarded with fine blooms. See growing information.
Avoid growing our delphiniums in the yellow areas unless you have an air-conditioned conservatory, where they will thrive.